[backport] add v1.6 changelog (#18932)

2 files changed, 928 insertions, 537 deletions

diff --git a/changelog.md b/changelog.md
index 1925878bf..ab63bd8b5 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,560 +1,24 @@
-# v1.6.x - yyyy-mm-dd
+# v1.8.x - yyyy-mm-dd
 
 
 
 ## Changes affecting backward compatibility
 
-- Deprecated `std/mersenne`.
 
-- `system.delete` had a most surprising behavior when the index passed to it was out of
-  bounds (it would delete the last entry then). Compile with `-d:nimStrictDelete` so
-  that an index error is produced instead. But be aware that your code might depend on
-  this quirky behavior so a review process is required on your part before you can
-  use `-d:nimStrictDelete`. To make this review easier, use the `-d:nimAuditDelete`
-  switch, it pretends that `system.delete` is deprecated so that it is easier to see
-  where it was used in your code.
-
-  `-d:nimStrictDelete` will become the default in upcoming versions.
-
-
-- `cuchar` is now deprecated as it aliased `char` where arguably it should have aliased `uint8`.
-  Please use `char` or `uint8` instead.
-
-- `repr` now doesn't insert trailing newline; previous behavior was very inconsistent,
-  see #16034. Use `-d:nimLegacyReprWithNewline` for previous behavior.
-
-- A type conversion from one enum type to another now produces an `[EnumConv]` warning.
-  You should use `ord` (or `cast`, but the compiler won't help, if you misuse it) instead.
-  ```
-  type A = enum a1, a2
-  type B = enum b1, b2
-  echo a1.B # produces a warning
-  echo a1.ord.B # produces no warning
-  ```
-
-- A dangerous implicit conversion to `cstring` now triggers a `[CStringConv]` warning.
-  This warning will become an error in future versions! Use an explicit conversion
-  like `cstring(x)` in order to silence the warning.
-
-- There is a new warning for *any* type conversion to enum that can be enabled via
-  `.warning[AnyEnumConv]:on` or `--warning:AnyEnumConv:on`.
-
-- Type mismatch errors now show more context, use `-d:nimLegacyTypeMismatch` for previous
-  behavior.
-
-- `math.round` now is rounded "away from zero" in JS backend which is consistent
-  with other backends. See #9125. Use `-d:nimLegacyJsRound` for previous behavior.
-
-- Changed the behavior of `uri.decodeQuery` when there are unencoded `=`
-  characters in the decoded values. Prior versions would raise an error. This is
-  no longer the case to comply with the HTML spec and other languages
-  implementations. Old behavior can be obtained with
-  `-d:nimLegacyParseQueryStrict`. `cgi.decodeData` which uses the same
-  underlying code is also updated the same way.
-
-- On POSIX systems, the default signal handlers used for Nim programs (it's
-  used for printing the stacktrace on fatal signals) will now re-raise the
-  signal for the OS default handlers to handle.
-
-  This lets the OS perform its default actions, which might include core
-  dumping (on select signals) and notifying the parent process about the cause
-  of termination.
-
-- On POSIX systems, we now ignore `SIGPIPE` signals, use `-d:nimLegacySigpipeHandler`
-  for previous behavior.
-
-- `hashes.hash` can now support `object` and `ref` (can be overloaded in user code),
-  if `-d:nimPreviewHashRef` is used. It is expected that this behavior
-  becomes the new default in upcoming versions.
-
-- `hashes.hash(proc|ptr|ref|pointer)` now calls `hash(int)` and honors `-d:nimIntHash1`,
-  `hashes.hash(closure)` has also been improved.
-
-- The unary slice `..b` was deprecated, use `0..b` instead.
-
-- Removed `.travis.yml`, `appveyor.yml.disabled`, `.github/workflows/ci.yml.disabled`.
-
-- `random.initRand(seed)` now produces non-skewed values for the 1st call to `rand()` after
-  initialization with a small (< 30000) seed. Use `-d:nimLegacyRandomInitRand` to restore
-  previous behavior for a transition time, see PR #17467.
-
-- With `-d:nimPreviewJsonutilsHoleyEnum`, `jsonutils` now can serialize/deserialize holey enums as regular enums (via `ord`) instead of as strings. It is expected that this behavior becomes the new default in upcoming versions. `toJson` now serializes `JsonNode`
-  as is via reference (without a deep copy) instead of treating `JsonNode` as a regular ref object,
-  this can be customized via `jsonNodeMode`.
-
-- `json` and `jsonutils` now serialize NaN, Inf, -Inf as strings, so that
-  `%[NaN, -Inf]` is the string `["nan","-inf"]` instead of `[nan,-inf]` which was invalid json.
-
-
-- `strformat` is now part of `include std/prelude`.
-
-- Deprecated `proc reversed*[T](a: openArray[T], first: Natural, last: int): seq[T]` in `std/algorithm`.
-
-- In `std/macros`, `treeRepr,lispRepr,astGenRepr` now represent SymChoice nodes in a collapsed way,
-  use `-d:nimLegacyMacrosCollapseSymChoice` to get previous behavior.
-
-- The configuration subsystem now allows for `-d:release` and `-d:danger` to work as expected.
-  The downside is that these defines now have custom logic that doesn't apply for
-  other defines.
-
-- `std/os`: `putEnv` now raises if the 1st argument contains a `=`
-
-- Renamed `-d:nimCompilerStackraceHints` to `-d:nimCompilerStacktraceHints`.
-
-- In `std/dom`, `Interval` is now a `ref object`, same as `Timeout`. Definitions of `setTimeout`,
-  `clearTimeout`, `setInterval`, `clearInterval` were updated.
-
-- With `-d:nimPreviewDotLikeOps`, dot-like operators (operators starting with `.`, but not with `..`)
-  now have the same precedence as `.`, so that `a.?b.c` is now parsed as `(a.?b).c` instead of `a.?(b.c)`.
-  A warning is generated when a dot-like operator is used without `-d:nimPreviewDotLikeOps`.
-
-- The allocator for Nintendo Switch, which was nonfunctional because
-  of breaking changes in libnx, was removed, in favour of the new `-d:nimAllocPagesViaMalloc` option.
-
-- `net.parseIpAddress` now only allows IPv4 addresses in strict form as defined
-  in [RFC 6943](https://www.rfc-editor.org/rfc/rfc6943#section-3.1.1).
-  Specifically, octal numbers in IPv4 addresses are no longer accepted (before
-  they were parsed as decimal numbers).
 
 ## Standard library additions and changes
 
-- `strformat`:
-  - added support for parenthesized expressions.
-  - added support for const string's instead of just string literals
-
-- `os.copyFile` is now 2.5x faster on OSX, by using `copyfile` from `copyfile.h`;
-  use `-d:nimLegacyCopyFile` for OSX < 10.5.
-
-- `system.addFloat` and `system.$` now can produce string representations of floating point numbers
-  that are minimal in size and that "roundtrip" (via the "Dragonbox" algorithm). This currently has
-  to be enabled via `-d:nimPreviewFloatRoundtrip`. It is expected that this behavior becomes the new default
-  in upcoming versions, as with other `nimPreviewX` define flags.
-
-- Fixed buffer overflow bugs in `net`.
-
-- Exported `sslHandle` from `net` and `asyncnet`.
-
-- Added `sections` iterator in `parsecfg`.
-
-- Make custom op in macros.quote work for all statements.
-
-- On Windows the SSL library now checks for valid certificates.
-  It uses the `cacert.pem` file for this purpose which was extracted
-  from `https://curl.se/ca/cacert.pem`. Besides
-  the OpenSSL DLLs (e.g. libssl-1_1-x64.dll, libcrypto-1_1-x64.dll) you
-  now also need to ship `cacert.pem` with your `.exe` file.
-
-- `typetraits`:
-  `distinctBase` now is identity instead of error for non distinct types.
-  Added `enumLen` to return the number of elements in an enum.
-  Added `HoleyEnum` for enums with holes, `OrdinalEnum` for enums without holes.
-  Added `hasClosure`.
-  Added `pointerBase` to return `T` for `ref T | ptr T`.
-
-- `prelude` now works with the JavaScript target.
-  Added `sequtils` import to `prelude`.
-  `prelude` can now be used via `include std/prelude`, but `include prelude` still works.
-
-- Added `almostEqual` in `math` for comparing two float values using a machine epsilon.
-
-- Added `clamp` in `math` which allows using a `Slice` to clamp to a value.
-
-- Added `ceilDiv` in `math` for round up integer division.
-
-- The JSON module can now handle integer literals and floating point literals of
-  arbitrary length and precision.
-  Numbers that do not fit the underlying `BiggestInt` or `BiggestFloat` fields are
-  kept as string literals and one can use external BigNum libraries to handle these.
-  The `parseFloat` family of functions also has now optional `rawIntegers` and
-  `rawFloats` parameters that can be used to enforce that all integer or float
-  literals remain in the "raw" string form so that client code can easily treat
-  small and large numbers uniformly.
-
-- Added `BackwardsIndex` overload for `JsonNode`.
-
-- `json.%`,`json.to`, `jsonutils.formJson`,`jsonutils.toJson` now work with `uint|uint64`
-  instead of raising (as in 1.4) or giving wrong results (as in 1.2).
-
-- `jsonutils` now handles `cstring` (including as Table key), and `set`.
-
-- added `jsonutils.jsonTo` overload with `opt = Joptions()` param.
-
-- `jsonutils.toJson` now supports customization via `ToJsonOptions`.
-
-- Added an overload for the `collect` macro that inferes the container type based
-  on the syntax of the last expression. Works with std seqs, tables and sets.
-
-- Added `randState` template that exposes the default random number generator.
-  Useful for library authors.
-
-- Added `random.initRand()` overload with no argument which uses the current time as a seed.
-
-- `random.initRand(seed)` now allows `seed == 0`.
-
-- Added `std/sysrand` module to get random numbers from a secure source
-  provided by the operating system.
-
-- Added `std/enumutils` module. Added `genEnumCaseStmt` macro that generates
-  case statement to parse string to enum.
-- Added `items` for enums with holes.
-- Added `symbolName` to return the enum symbol name ignoring the human readable name.
-- Added `symbolRank` to return the index in which an enum member is listed in an enum.
-
-- Removed deprecated `iup` module from stdlib, it has already moved to
-  [nimble](https://github.com/nim-lang/iup).
-
-- various functions in `httpclient` now accept `url` of type `Uri`. Moreover `request` function's
-  `httpMethod` argument of type `string` was deprecated in favor of `HttpMethod` enum type.
-
-- `nodejs` backend now supports osenv: `getEnv`, `putEnv`, `envPairs`, `delEnv`, `existsEnv`.
-
-- Added `cmpMem` to `system`.
-
-- `doAssertRaises` now correctly handles foreign exceptions.
-
-- Added `asyncdispatch.activeDescriptors` that returns the number of currently
-  active async event handles/file descriptors.
-
-- Added `getPort` to `asynchttpserver`.
-
-- `--gc:orc` is now 10% faster than previously for common workloads. If
-  you have trouble with its changed behavior, compile with `-d:nimOldOrc`.
-
-- `os.FileInfo` (returned by `getFileInfo`) now contains `blockSize`,
-  determining preferred I/O block size for this file object.
-
-- Added `os.getCacheDir()` to return platform specific cache directory.
-
-- Added a simpler to use `io.readChars` overload.
-
-- Added `**` to jsffi.
-
-- `writeStackTrace` is available in JS backend now.
-
-- Added `decodeQuery` to `std/uri`.
-
-- `strscans.scanf` now supports parsing single characters.
-
-- `strscans.scanTuple` added which uses `strscans.scanf` internally,
-  returning a tuple which can be unpacked for easier usage of `scanf`.
-
-- Added `setutils.toSet` that can take any iterable and convert it to a built-in `set`,
-  if the iterable yields a built-in settable type.
-
-- Added `setutils.fullSet` which returns a full built-in `set` for a valid type.
-
-- Added `setutils.complement` which returns the complement of a built-in `set`.
-
-- Added `setutils.[]=`.
-
-- Added `math.isNaN`.
-
-- Added `jsbigints` module, arbitrary precision integers for JavaScript target.
-
-- Added `math.copySign`.
-
-- Added new operations for singly- and doubly linked lists: `lists.toSinglyLinkedList`
-  and `lists.toDoublyLinkedList` convert from `openArray`s; `lists.copy` implements
-  shallow copying; `lists.add` concatenates two lists - an O(1) variation that consumes
-  its argument, `addMoved`, is also supplied.
-
-- Added `euclDiv` and `euclMod` to `math`.
-
-- Added `httpcore.is1xx` and missing HTTP codes.
-
-- Added `jsconsole.jsAssert` for JavaScript target.
-
-- Added `posix_utils.osReleaseFile` to get system identification from `os-release` file on Linux and the BSDs.
-  https://www.freedesktop.org/software/systemd/man/os-release.html
-
-- Added `socketstream` module that wraps sockets in the stream interface
-
-- Added `sugar.dumpToString` which improves on `sugar.dump`.
-
-- Added `math.signbit`.
-
-- Removed the optional `longestMatch` parameter of the `critbits._WithPrefix` iterators (it never worked reliably)
-
-- In `lists`: renamed `append` to `add` and retained `append` as an alias;
-  added `prepend` and `prependMoved` analogously to `add` and `addMoved`;
-  added `remove` for `SinglyLinkedList`s.
-
-- Deprecated `any`. See https://github.com/nim-lang/RFCs/issues/281
-
-- Added optional `options` argument to `copyFile`, `copyFileToDir`, and
-  `copyFileWithPermissions`. By default, on non-Windows OSes, symlinks are
-  followed (copy files symlinks point to); on Windows, `options` argument is
-  ignored and symlinks are skipped.
-
-- On non-Windows OSes, `copyDir` and `copyDirWithPermissions` copy symlinks as
-  symlinks (instead of skipping them as it was before); on Windows symlinks are
-  skipped.
-
-- On non-Windows OSes, `moveFile` and `moveDir` move symlinks as symlinks
-  (instead of skipping them sometimes as it was before).
-
-- Added optional `followSymlinks` argument to `setFilePermissions`.
-
-- Added `os.isAdmin` to tell whether the caller's process is a member of the
-  Administrators local group (on Windows) or a root (on POSIX).
-
-- Added experimental `linenoise.readLineStatus` to get line and status (e.g. ctrl-D or ctrl-C).
-
-- Added `compilesettings.SingleValueSetting.libPath`.
-
-- `std/wrapnils` doesn't use `experimental:dotOperators` anymore, avoiding
-  issues like https://github.com/nim-lang/Nim/issues/13063 (which affected error messages)
-  for modules importing `std/wrapnils`.
-  Added `??.` macro which returns an `Option`.
-  `std/wrapnils` can now be used to protect against `FieldDefect` errors in
-  case objects, generates optimal code (no overhead compared to manual
-  if-else branches), and preserves lvalue semantics which allows modifying
-  an expression.
-
-- Added `math.frexp` overload procs. Deprecated `c_frexp`, use `frexp` instead.
-
-- `parseopt.initOptParser` has been made available and `parseopt` has been
-  added back to `prelude` for all backends. Previously `initOptParser` was
-  unavailable if the `os` module did not have `paramCount` or `paramStr`,
-  but the use of these in `initOptParser` were conditionally to the runtime
-  arguments passed to it, so `initOptParser` has been changed to raise
-  `ValueError` when the real command line is not available. `parseopt` was
-  previously excluded from `prelude` for JS, as it could not be imported.
-
-- Added `system.prepareStrMutation` for better support of low
-  level `moveMem`, `copyMem` operations for Orc's copy-on-write string
-  implementation.
-
-- Added `std/strbasics` for high performance string operations.
-  Added `strip`, `setSlice`, `add(a: var string, b: openArray[char])`.
-
-- `std/options` changed `$some(3)` to `"some(3)"` instead of `"Some(3)"`
-  and `$none(int)` to `"none(int)"` instead of `"None[int]"`.
-
-- Added `algorithm.merge`.
-
-- Added `std/jsfetch` module [Fetch](https://developer.mozilla.org/docs/Web/API/Fetch_API) wrapper for JavaScript target.
-
-- Added `std/jsheaders` module [Headers](https://developer.mozilla.org/en-US/docs/Web/API/Headers) wrapper for JavaScript target.
-
-- Added `std/jsformdata` module [FormData](https://developer.mozilla.org/en-US/docs/Web/API/FormData) wrapper for JavaScript target.
-
-- `system.addEscapedChar` now renders `\r` as `\r` instead of `\c`, to be compatible
-  with most other languages.
-
-- Removed support for named procs in `sugar.=>`.
-
-- Added `jscore.debugger` to [call any available debugging functionality, such as breakpoints.](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger).
-
-- Added `htmlgen.portal` for [making "SPA style" pages using HTML only](https://web.dev/hands-on-portals).
-
-- `std/times`:
-  Added `ZZZ` and `ZZZZ` patterns to `times.nim` `DateTime` parsing, to match time
-  zone offsets without colons, e.g. `UTC+7 -> +0700`.
-
-  Added `dateTime` and deprecated `initDateTime`.
-
-- Added `jsconsole.dir`, `jsconsole.dirxml`, `jsconsole.timeStamp`.
-
-- Added dollar `$` and `len` for `jsre.RegExp`.
-
-- Added `std/tasks`.
-
-- Added `hasDataBuffered` to `asyncnet`.
-
-- Added `std/tempfiles`.
-
-- Added `genasts.genAst` that avoids the problems inherent with `quote do` and can
-  be used as a replacement.
-
-- Added `copyWithin` [for `seq` and `array` for JavaScript targets](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/copyWithin).
-
-- Fixed premature garbage collection in asyncdispatch, when a stack trace override is in place.
-
-- Added setCurrentException for JS backend.
-
-- Added `dom.scrollIntoView` proc with options
-
-- Added `dom.setInterval`, `dom.clearInterval` overloads.
-
-- Merged `dom_extensions` module into `dom` module,
-  it was a module with a single line, see https://github.com/nim-lang/RFCs/issues/413
-
-- Allow reading parameters when compiling for Nintendo Switch.
-
-- Deprecated `sequtils.delete` and added an overload taking a `Slice` that raises a defect
-  if the slice is out of bounds, likewise with `strutils.delete`.
 
 
 ## Language changes
 
-- The `cstring` doesn't support `[]=` operator in JS backend.
-
-- nil dereference is not allowed at compile time. `cast[ptr int](nil)[]` is rejected at compile time.
-
-- The required name of case statement macros for the experimental
-  `caseStmtMacros` feature has changed from `match` to `` `case` ``.
-
-- `typedesc[Foo]` now renders as such instead of `type Foo` in compiler messages.
-
-- The unary minus in `-1` is now part of the integer literal, it is now parsed as a single token.
-  This implies that edge cases like `-128'i8` finally work correctly.
-
-- Custom numeric literals (e.g. `-128'bignum`) are now supported.
-
-- Tuple expressions are now parsed consistently as
-  `nnkTupleConstr` node. Will affect macros expecting nodes to be of `nnkPar`.
-
-- Added `iterable[T]` type class to match called iterators, which enables writing:
-  `template fn(a: iterable)` instead of `template fn(a: untyped)`
-
-- A new import syntax `import foo {.all.}` now allows to import all symbols (public or private)
-  from `foo`. This can be useful for testing purposes.
-
-- Added a new module `std/importutils`, and an API `privateAccess`, which allows access to private fields
-  for an object type in the current scope.
-
-- `typeof(voidStmt)` now works and returns `void`.
-
-- The `gc:orc` algorithm was refined so that custom container types can participate in the
-  cycle collection process. See the documentation of `=trace` for more details.
-
-- On embedded devices `malloc` can now be used instead of `mmap` via `-d:nimAllocPagesViaMalloc`.
-  This is only supported for `--gc:orc` or `--gc:arc`.
-
-- The effect system was refined and there is a new `.effectsOf` annotation that does
-  explicitly what was previously done implicitly. See the manual for details.
-  To write code that is portable with older Nim versions, use this idiom:
-
-```nim
-
-when defined(nimHasEffectsOf):
-  {.experimental: "strictEffects".}
-else:
-  {.pragma: effectsOf.}
-
-proc mysort(s: seq; cmp: proc(a, b: T): int) {.effectsOf: cmp.}
-
-```
-
-  To enable the new effect system, use --experimental:strictEffects.
-
-
-- Nim now supports a small subset of Unicode operators as operator symbols.
-  The supported symbols are: "∙ ∘ × ★ ⊗ ⊘ ⊙ ⊛ ⊠ ⊡ ∩ ∧ ⊓ ± ⊕ ⊖ ⊞ ⊟ ∪ ∨ ⊔".
-  To enable this feature, use `--experimental:unicodeOperators`. Note that due
-  to parser limitations you **cannot** enable this feature via a
-  pragma `{.experimental: "unicodeOperators".}` reliably, you need to enable
-  it via the command line or in a configuration file.
-
-- There is a new `cast` section `{.cast(uncheckedAssign).}: body` that disables some
-  compiler checks regarding `case objects`. This allows serialization libraries
-  to avoid ugly, non-portable solutions. See https://github.com/nim-lang/RFCs/issues/407
-  for more details.
-
-- Enum values can now be overloaded. This needs to be enabled
-  via `{.experimental: "overloadableEnums".}`. We hope that this feature allows for the
-  development of more fluent (less ugly) APIs. See https://github.com/nim-lang/RFCs/issues/373
-  for more details.
 
 
 ## Compiler changes
 
-- Added `--declaredLocs` to show symbol declaration location in messages.
-
-- You can now enable/disable VM tracing in user code via `vmutils.vmTrace`.
-
-- Deprecated `TaintedString` and `--taintmode`.
-
-- Deprecated `--nilseqs` which is now a noop.
-
-- Added `--spellSuggest` to show spelling suggestions on typos.
-
-- Added `--filenames:abs|canonical|legacyRelProj` which replaces --listFullPaths:on|off
-
-- Added `--processing:dots|filenames|off` which customizes `hintProcessing`
-
-- Added `--unitsep:on|off` to control whether to add ASCII unit separator `\31` before a newline
- for every generated message (potentially multiline), so tooling can tell when messages start and end.
-
-- Source+Edit links now appear on top of every docgen'd page when
-  `nim doc --git.url:url ...` is given.
-
-- Added `nim --eval:cmd` to evaluate a command directly, see `nim --help`.
-
-- VM now supports `addr(mystring[ind])` (index + index assignment)
-
-- Added `--hintAsError` with similar semantics as `--warningAsError`.
-
-- TLS: OSX now uses native TLS (`--tlsEmulation:off`), TLS now works with importcpp non-POD types,
-  such types must use `.cppNonPod` and `--tlsEmulation:off`should be used.
-
-- Now array literals(JS backend) uses JS typed arrays when the corresponding js typed array exists,
-  for example `[byte(1), 2, 3]` generates `new Uint8Array([1, 2, 3])`.
-
-- docgen: rst files can now use single backticks instead of double backticks and correctly render
-  in both rst2html (as before) as well as common tools rendering rst directly (e.g. github), by
-  adding: `default-role:: code` directive inside the rst file, which is now handled by rst2html.
-
-- Added `-d:nimStrictMode` in CI in several places to ensure code doesn't have certain hints/warnings
-
-- Added `then`, `catch` to `asyncjs`, for now hidden behind `-d:nimExperimentalAsyncjsThen`.
-
-- `--newruntime` and `--refchecks` are deprecated.
-
-- Added `unsafeIsolate` and `extract` to `std/isolation`.
-
-- `--hint:CC` now goes to stderr (like all other hints) instead of stdout.
-
-- `--hint:all:on|off` is now supported to select or deselect all hints; it
-  differs from `--hints:on|off` which acts as a (reversible) gate.
-  Likewise with `--warning:all:on|off`.
-
-- json build instructions are now generated in `$nimcache/outFileBasename.json`
-  instead of `$nimcache/projectName.json`. This allows avoiding recompiling a given project
-  compiled with different options if the output file differs.
-
-- `--usenimcache` (implied by `nim r main`) now generates an output file that includes a hash of
-  some of the compilation options, which allows caching generated binaries:
-  nim r main # recompiles
-  nim r -d:foo main # recompiles
-  nim r main # uses cached binary
-  nim r main arg1 arg2 # ditto (runtime arguments are irrelevant)
-
-- `nim r` now supports cross compilation from unix to windows when specifying `-d:mingw` by using wine,
-  e.g.: `nim r --eval:'import os; echo "a" / "b"'` prints `a\b`
-
-- `nim` can compile version 1.4.0 as follows: `nim c --lib:lib --stylecheck:off -d:nimVersion140 compiler/nim`.
-  `-d:nimVersion140` is not needed for bootstrapping, only for building 1.4.0 from devel.
-
-- The style checking of the compiler now supports a `--styleCheck:usages` switch. This switch
-  enforces that every symbol is written as it was declared, not enforcing
-  the official Nim style guide. To be enabled, this has to be combined either
-  with `--styleCheck:error` or `--styleCheck:hint`.
 
 
 ## Tool changes
 
-- `nimscript` now handles `except Exception as e`.
-
-- `nim e` now accepts arbitrary file extensions for the nimscript file,
-  although `.nims` is still the preferred extension in general.
-
-- Latex doc generation is revised: output `.tex` files should be compiled
-  by `xelatex` (not by `pdflatex` as before). Now default Latex settings
-  provide support for Unicode and do better job for avoiding margin overflows.
-
-- Implemented `doc2tex` compiler command which converts documentation in
-  `.nim` files to Latex.
-
-- The rst parser now supports markdown table syntax.
-  Known limitations:
-  - cell alignment is not supported, i.e. alignment annotations in a delimiter
-    row (`:---`, `:--:`, `---:`) are ignored,
-  - every table row must start with `|`, e.g. `| cell 1 | cell 2 |`.
 
-- `fusion` is now un-bundled from nim, `./koch fusion` will
-  install it via nimble at a fixed hash.
 
-- testament: added `nimoutFull: bool` spec to compare full output of compiler
-  instead of a subset.
diff --git a/changelogs/changelog_1_6_0.md b/changelogs/changelog_1_6_0.md
new file mode 100644
index 000000000..1ce6c2093
--- /dev/null
+++ b/changelogs/changelog_1_6_0.md
@@ -0,0 +1,927 @@
+# v1.6.0 - 2021-10-14
+
+
+
+# Major new features
+
+With so many new features, pinpointing the most salient ones is a subjective exercise,
+but here are a select few:
+
+
+## `iterable[T]`
+
+The `iterable[T]` type class was added to match called iterators,
+which solves a number of long-standing issues related to iterators.
+Example:
+
+```nim
+iterator iota(n: int): int =
+  for i in 0..<n: yield i
+
+# previously, you'd need `untyped`, which caused other problems such as lack
+# of type inference, overloading issues, and MCS.
+template sumOld(a: untyped): untyped = # no type inference possible
+  var result: typeof(block:(for ai in a: ai))
+  for ai in a: result += ai
+  result
+
+assert sumOld(iota(3)) == 0 + 1 + 2
+
+# now, you can write:
+template sum[T](a: iterable[T]): T =
+  # `template sum(a: iterable): auto =` would also be possible
+  var result: T
+  for ai in a: result += ai
+  result
+
+assert sum(iota(3)) == 0 + 1 + 2 # or `iota(3).sum`
+```
+
+In particular iterable arguments can now be used with the method call syntax. For example:
+```nim
+import std/[sequtils, os]
+echo walkFiles("*").toSeq # now works
+```
+See PR [#17196](https://github.com/nim-lang/Nim/pull/17196) for additional details.
+
+
+## Strict effects
+
+The effect system was refined and there is a new `.effectsOf` annotation that does
+explicitly what was previously done implicitly. See the
+[manual](https://nim-lang.github.io/Nim/manual.html#effect-system-effectsof-annotation)
+for more details.
+To write code that is portable with older Nim versions, use this idiom:
+
+```nim
+when defined(nimHasEffectsOf):
+  {.experimental: "strictEffects".}
+else:
+  {.pragma: effectsOf.}
+
+proc mysort(s: seq; cmp: proc(a, b: T): int) {.effectsOf: cmp.}
+```
+
+To enable the new effect system, compile with `--experimental:strictEffects`.
+See also [#18777](https://github.com/nim-lang/Nim/pull/18777) and RFC
+[#408](https://github.com/nim-lang/RFCs/issues/408).
+
+
+## Private imports and private field access
+
+A new import syntax `import foo {.all.}` now allows importing all symbols
+(public or private) from `foo`.
+This can be useful for testing purposes or for more flexibility in project organization.
+
+Example:
+```nim
+from system {.all.} as system2 import nil
+echo system2.ThisIsSystem # ThisIsSystem is private in `system`
+import os {.all.} # weirdTarget is private in `os`
+echo weirdTarget # or `os.weirdTarget`
+```
+
+Added a new module `std/importutils`, and an API `privateAccess`, which allows access
+to private fields for an object type in the current scope.
+
+Example:
+```nim
+import times
+from std/importutils import privateAccess
+block:
+  let t = now()
+  # echo t.monthdayZero # Error: undeclared field: 'monthdayZero' for type times.DateTime
+  privateAccess(typeof(t)) # enables private access in this scope
+  echo t.monthdayZero # ok
+```
+
+See PR [#17706](https://github.com/nim-lang/Nim/pull/17706) for additional details.
+
+
+## `nim --eval:cmd`
+
+Added `nim --eval:cmd` to evaluate a command directly, e.g.: `nim --eval:"echo 1"`.
+It defaults to `e` (nimscript) but can also work with other commands, e.g.:
+```bash
+find . | nim r --eval:'import strutils; for a in stdin.lines: echo a.toUpper'
+```
+
+```bash
+# use as a calculator:
+nim --eval:'echo 3.1 / (1.2+7)'
+# explore a module's APIs, including private symbols:
+nim --eval:'import os {.all.}; echo weirdTarget'
+# use a custom backend:
+nim r -b:js --eval:"import std/jsbigints; echo 2'big ** 64'big"
+```
+
+See PR [#15687](https://github.com/nim-lang/Nim/pull/15687) for more details.
+
+
+## Round-trip float to string
+
+`system.addFloat` and `system.$` now can produce string representations of
+floating point numbers that are minimal in size and possess round-trip and correct
+rounding guarantees (via the
+[Dragonbox](https://raw.githubusercontent.com/jk-jeon/dragonbox/master/other_files/Dragonbox.pdf) algorithm).
+This currently has to be enabled via `-d:nimPreviewFloatRoundtrip`.
+It is expected that this behavior becomes the new default in upcoming versions,
+as with other `nimPreviewX` define flags.
+
+Example:
+```nim
+from math import round
+let a = round(9.779999999999999, 2)
+assert a == 9.78
+echo a # with `-d:nimPreviewFloatRoundtrip`: 9.78, like in python3 (instead of  9.779999999999999)
+```
+
+
+## New `std/jsbigints` module
+
+Provides arbitrary precision integers for the JS target. See PR
+[#16409](https://github.com/nim-lang/Nim/pull/16409).
+Example:
+```nim
+import std/jsbigints
+assert 2'big ** 65'big == 36893488147419103232'big
+echo 0xdeadbeef'big shl 4'big # 59774856944n
+```
+
+
+## New `std/sysrand` module
+Cryptographically secure pseudorandom number generator,
+allows generating random numbers from a secure source provided by the operating system.
+Example:
+```nim
+import std/sysrand
+assert urandom(1234) != urandom(1234) # unlikely to fail in practice
+```
+See PR [#16459](https://github.com/nim-lang/Nim/pull/16459).
+
+
+## New module: `std/tempfiles`
+
+Allows creating temporary files and directories, see PR
+[#17361](https://github.com/nim-lang/Nim/pull/17361) and followups.
+```nim
+import std/tempfiles
+let tmpPath = genTempPath("prefix", "suffix.log", "/tmp/")
+# tmpPath looks like: /tmp/prefixpmW1P2KLsuffix.log
+
+let dir = createTempDir("tmpprefix_", "_end")
+# created dir looks like: getTempDir() / "tmpprefix_YEl9VuVj_end"
+
+let (cfile, path) = createTempFile("tmpprefix_", "_end.tmp")
+# path looks like: getTempDir() / "tmpprefix_FDCIRZA0_end.tmp"
+cfile.write "foo"
+cfile.setFilePos 0
+assert readAll(cfile) == "foo"
+close cfile
+assert readFile(path) == "foo"
+```
+
+
+## User-defined literals
+
+Custom numeric literals (e.g. `-128'bignum`) are now supported.
+Additionally, the unary minus in `-1` is now part of the integer literal, i.e.
+it is now parsed as a single token.
+This implies that edge cases like `-128'i8` finally work correctly.
+Example:
+```nim
+func `'big`*(num: cstring): JsBigInt {.importjs: "BigInt(#)".}
+assert 0xffffffffffffffff'big == (1'big shl 64'big) - 1'big
+```
+
+
+## Dot-like operators
+
+With `-d:nimPreviewDotLikeOps`, dot-like operators (operators starting with `.`,
+but not with `..`) now have the same precedence as `.`, so that `a.?b.c` is now
+parsed as `(a.?b).c` instead of `a.?(b.c)`.
+A warning is generated when a dot-like operator is used without `-d:nimPreviewDotLikeOps`.
+
+An important use case is to enable dynamic fields without affecting the
+built-in `.` operator, e.g. for `std/jsffi`, `std/json`, `pkg/nimpy`. Example:
+```nim
+import std/json
+template `.?`(a: JsonNode, b: untyped{ident}): JsonNode =
+  a[astToStr(b)]
+let j = %*{"a1": {"a2": 10}}
+assert j.?a1.?a2.getInt == 10
+```
+
+
+## Block arguments now support optional parameters
+
+This solves a major pain point for routines accepting block parameters,
+see PR [#18631](https://github.com/nim-lang/Nim/pull/18631) for details:
+
+```nim
+template fn(a = 1, b = 2, body) = discard
+fn(1, 2): # already works
+  bar
+fn(a = 1): # now works
+  bar
+```
+
+Likewise with multiple block arguments via `do`:
+```nim
+template fn(a = 1, b = 2, body1, body2) = discard
+fn(a = 1): # now works
+  bar1
+do:
+  bar2
+```
+
+
+# Other new features
+
+## New and deprecated modules
+
+The following modules were added (they are discussed in the rest of the text):
+- `std/enumutils`
+- `std/genasts`
+- `std/importutils`
+- `std/jsbigints`
+- `std/jsfetch`
+- `std/jsformdata`
+- `std/jsheaders`
+- `std/packedsets`
+- `std/setutils`
+- `std/socketstreams`
+- `std/strbasics`
+- `std/sysrand`
+- `std/tasks`
+- `std/tempfiles`
+- `std/vmutils`
+
+- Deprecated `std/mersenne`.
+- Removed deprecated `std/iup` module from stdlib; it has already moved to
+  [nimble](https://github.com/nim-lang/iup).
+
+
+## New `std/jsfetch` module
+
+Provides a wrapper for JS Fetch API.
+Example:
+```nim
+# requires -d:nimExperimentalAsyncjsThen
+import std/[jsfetch, asyncjs, jsconsole, jsffi, sugar]
+proc fn {.async.} =
+  await fetch("https://api.github.com/users/torvalds".cstring)
+    .then((response: Response) => response.json())
+    .then((json: JsObject) => console.log(json))
+    .catch((err: Error) => console.log("Request Failed", err))
+discard fn()
+```
+
+
+## New `std/tasks` module
+
+Provides basic primitives for creating parallel programs.
+Example:
+```nim
+import std/tasks
+var num = 0
+proc hello(a: int) = num+=a
+
+let b = toTask hello(13) # arguments must be isolated, see `std/isolation`
+b.invoke()
+assert num == 13
+b.invoke() # can be called again
+assert num == 26
+```
+
+
+## New module: `std/genasts`
+
+Provides an API `genAst` that avoids the problems inherent with `quote do` and can
+be used as a replacement.
+Example showing how this could be used for writing a simplified version of `unittest.check`:
+```nim
+import std/[genasts, macros, strutils]
+macro check2(cond: bool): untyped =
+  assert cond.kind == nnkInfix, "$# not implemented" % $cond.kind
+  result = genAst(cond, s = repr(cond), lhs = cond[1], rhs = cond[2]):
+    # each local symbol we access must be explicitly captured
+    if not cond:
+      doAssert false, "'$#'' failed: lhs: '$#', rhs: '$#'" % [s, $lhs, $rhs]
+let a = 3
+check2 a*2 == a+3
+if false: check2 a*2 < a+1 # would error with: 'a * 2 < a + 1'' failed: lhs: '6', rhs: '4'
+```
+
+See PR [#17426](https://github.com/nim-lang/Nim/pull/17426) for details.
+
+
+## New module: `std/setutils`
+
+- Added `setutils.toSet` that can take any iterable and convert it to a built-in `set`,
+  if the iterable yields a built-in settable type.
+- Added `setutils.fullSet` which returns a full built-in `set` for a valid type.
+- Added `setutils.complement` which returns the complement of a built-in `set`.
+- Added `setutils.[]=`.
+
+
+## New module: `std/enumutils`
+
+- Added `genEnumCaseStmt` macro that generates
+  case statement to parse string to enum.
+- Added `items` for enums with holes.
+- Added `symbolName` to return the `enum` symbol name ignoring the human-readable name.
+- Added `symbolRank` to return the index in which an `enum` member is listed in an enum.
+
+
+## `system`
+
+- Added `system.prepareMutation` for better support of low
+  level `moveMem`, `copyMem` operations for `gc:orc`'s copy-on-write string
+  implementation.
+- `system.addEscapedChar` now renders `\r` as `\r` instead of `\c`, to be compatible
+  with most other languages.
+- Added `cmpMem` to `system`.
+- `doAssertRaises` now correctly handles foreign exceptions.
+- `addInt` now supports unsigned integers.
+
+Compatibility notes:
+- `system.delete` had surprising behavior when the index passed to it was out of
+  bounds (it would delete the last entry then). Compile with `-d:nimStrictDelete` so
+  that an index error is produced instead. Be aware however that your code might depend on
+  this quirky behavior so a review process is required on your part before you can
+  use `-d:nimStrictDelete`. To make this review easier, use the `-d:nimAuditDelete`
+  switch, which pretends that `system.delete` is deprecated so that it is easier
+  to see where it was used in your code.
+  `-d:nimStrictDelete` will become the default in upcoming versions.
+- `cuchar` is now deprecated as it aliased `char` where arguably it should have aliased `uint8`.
+  Please use `char` or `uint8` instead.
+- `repr` now doesn't insert trailing newlines; the previous behavior was very inconsistent,
+  see [#16034](https://github.com/nim-lang/Nim/pull/16034).
+  Use `-d:nimLegacyReprWithNewline` for the previous behavior.
+  `repr` now also renders ASTs correctly for user defined literals, setters, `do`, etc.
+- Deprecated `any`. See RFC [#281](https://github.com/nim-lang/RFCs/issues/281).
+- The unary slice `..b` was deprecated, use `0..b` instead.
+
+
+## `std/math`
+
+- Added `almostEqual` for comparing two float values using a machine epsilon.
+- Added `clamp` which allows using a `Slice` to clamp to a value.
+- Added `ceilDiv` for integer division that rounds up.
+- Added `isNaN`.
+- Added `copySign`.
+- Added `euclDiv` and `euclMod`.
+- Added `signbit`.
+- Added `frexp` overload procs. Deprecated `c_frexp`, use `frexp` instead.
+
+Compatibility notes:
+- `math.round` now rounds "away from zero" in the JS backend, which is consistent
+  with other backends. See [#9125](https://github.com/nim-lang/Nim/pull/9125).
+  Use `-d:nimLegacyJsRound` for the previous behavior.
+
+
+## Random number generators: `std/random`, `std/sysrand`, `std/oids`
+
+- Added `std/sysrand` module (see details above).
+- Added `randState` template that exposes the default random number generator.
+  Useful for library authors.
+- Added `initRand()` overload with no argument which uses the current time as a seed.
+- `initRand(seed)` now allows `seed == 0`.
+- Fixed overflow bugs.
+- Fix `initRand` to avoid random number sequences overlapping, refs
+  [#18744](https://github.com/nim-lang/Nim/pull/18744).
+- `std/oids` now uses `std/random`.
+
+Compatibility notes:
+- Deprecated `std/mersenne`.
+- `random.initRand(seed)` now produces non-skewed values for the first call to
+  `rand()` after initialization with a small (< 30000) seed.
+  Use `-d:nimLegacyRandomInitRand` to restore previous behavior for a transition
+  time, see PR [#17467](https://github.com/nim-lang/Nim/pull/17467).
+
+
+## `std/json`, `std/jsonutils`
+
+- With `-d:nimPreviewJsonutilsHoleyEnum`, `jsonutils` now can serialize/deserialize
+  holey enums as regular enums (via `ord`) instead of as strings.
+  It is expected that this behavior becomes the new default in upcoming versions.
+ `toJson` now serializes `JsonNode` as is via reference (without a deep copy)
+   instead of treating `JsonNode` as a regular ref object,
+  this can be customized via `jsonNodeMode`.
+- `std/json` and `std/jsonutils` now serialize `NaN`, `Inf`, `-Inf` as strings,
+  so that `%[NaN, -Inf]` is the string `["nan","-inf"]` instead of `[nan,-inf]`
+  which was invalid JSON.
+- `std/json` can now handle integer literals and floating point literals of
+  arbitrary length and precision.
+  Numbers that do not fit the underlying `BiggestInt` or `BiggestFloat` fields are
+  kept as string literals and one can use external BigNum libraries to handle these.
+  The `parseFloat` family of functions also has now optional `rawIntegers` and
+  `rawFloats` parameters that can be used to enforce that all integer or float
+  literals remain in the "raw" string form so that client code can easily treat
+  small and large numbers uniformly.
+- Added `BackwardsIndex` overload for `JsonNode`.
+- `json.%`,`json.to`, `jsonutils.fromJson`,`jsonutils.toJson` now work with `uint|uint64`
+  instead of raising (as in 1.4) or giving wrong results (as in 1.2).
+- `std/jsonutils` now handles `cstring` (including as Table key), and `set`.
+- Added `jsonutils.jsonTo` overload with `opt = Joptions()` param.
+- `jsonutils.toJson` now supports customization via `ToJsonOptions`.
+- `std/json`, `std/jsonutils` now support round-trip serialization when
+  `-d:nimPreviewFloatRoundtrip` is used.
+
+
+## `std/typetraits`, `std/compilesettings`
+
+- `distinctBase` now is identity instead of error for non distinct types.
+- `distinctBase` now allows controlling whether to be recursive or not.
+- Added `enumLen` to return the number of elements in an enum.
+- Added `HoleyEnum` for enums with holes, `OrdinalEnum` for enums without holes.
+- Added `hasClosure`.
+- Added `pointerBase` to return `T` for `ref T | ptr T`.
+- Added `compilesettings.SingleValueSetting.libPath`.
+
+
+## networking: `std/net`, `std/asyncnet`, `std/htmlgen`, `std/httpclient`, `std/asyncdispatch`, `std/asynchttpserver`, `std/httpcore`
+
+- Fixed buffer overflow bugs in `std/net`.
+- Exported `sslHandle` from `std/net` and `std/asyncnet`.
+- Added `hasDataBuffered` to `std/asyncnet`.
+- Various functions in `std/httpclient` now accept `url` of type `Uri`.
+  Moreover, the `request` function's `httpMethod` argument of type `string` was
+  deprecated in favor of `HttpMethod` `enum` type; see
+  [#15919](https://github.com/nim-lang/Nim/pull/15919).
+- Added `asyncdispatch.activeDescriptors` that returns the number of currently
+  active async event handles/file descriptors.
+- Added `getPort` to `std/asynchttpserver` to resolve OS-assigned `Port(0)`;
+  this is usually recommended instead of hardcoding ports which can lead to
+  "Address already in use" errors.
+- Fixed premature garbage collection in `std/asyncdispatch`, when a stacktrace
+  override is in place.
+- Added `httpcore.is1xx` and missing HTTP codes.
+- Added `htmlgen.portal` for [making "SPA style" pages using HTML only](https://web.dev/hands-on-portals).
+
+Compatibility notes:
+- On Windows, the SSL library now checks for valid certificates.
+  For this purpose it uses the `cacert.pem` file, which was extracted
+  from `https://curl.se/ca/cacert.pem`. Besides
+  the OpenSSL DLLs (e.g. `libssl-1_1-x64.dll`, `libcrypto-1_1-x64.dll`) you
+  now also need to ship `cacert.pem` with your `.exe` file.
+
+
+## `std/hashes`
+
+- `hashes.hash` can now support `object` and `ref` (can be overloaded in user code),
+  if `-d:nimPreviewHashRef` is used. It is expected that this behavior
+  becomes the new default in upcoming versions.
+- `hashes.hash(proc|ptr|ref|pointer)` now calls `hash(int)` and honors `-d:nimIntHash1`.
+  `hashes.hash(closure)` has also been improved.
+
+
+## OS: `std/os`, `std/io`, `std/socketstream`, `std/linenoise`, `std/tempfiles`
+
+- `os.FileInfo` (returned by `getFileInfo`) now contains `blockSize`,
+  determining preferred I/O block size for this file object.
+- Added `os.getCacheDir()` to return platform specific cache directory.
+- Improved `os.getTempDir()`, see PR [#16914](https://github.com/nim-lang/Nim/pull/16914).
+- Added `os.isAdmin` to tell whether the caller's process is a member of the
+  Administrators local group (on Windows) or a root (on POSIX).
+- Added optional `options` argument to `copyFile`, `copyFileToDir`, and
+  `copyFileWithPermissions`. By default, on non-Windows OSes, symlinks are
+  followed (copy files symlinks point to); on Windows, `options` argument is
+  ignored and symlinks are skipped.
+- On non-Windows OSes, `copyDir` and `copyDirWithPermissions` copy symlinks as
+  symlinks (instead of skipping them as it was before); on Windows symlinks are
+  skipped.
+- On non-Windows OSes, `moveFile` and `moveDir` move symlinks as symlinks
+  (instead of skipping them sometimes as it was before).
+- Added optional `followSymlinks` argument to `setFilePermissions`.
+- Added a simpler to use `io.readChars` overload.
+- Added `socketstream` module that wraps sockets in the stream interface.
+- Added experimental `linenoise.readLineStatus` to get line and status (e.g. ctrl-D or ctrl-C).
+
+
+## Environment variable handling
+
+- Empty environment variable values are now supported across OS's and backends.
+- Environment variable APIs now work in multithreaded scenarios, by delegating to
+  direct OS calls instead of trying to keep track of the environment.
+- `putEnv`, `delEnv` now work at compile time.
+- NodeJS backend now supports osenv: `getEnv`, `putEnv`, `envPairs`, `delEnv`, `existsEnv`.
+
+Compatibility notes:
+- `std/os`: `putEnv` now raises if the first argument contains a `=`.
+
+
+## POSIX
+
+- On POSIX systems, the default signal handlers used for Nim programs (it's
+  used for printing the stacktrace on fatal signals) will now re-raise the
+  signal for the OS default handlers to handle.
+  This lets the OS perform its default actions, which might include core
+  dumping (on select signals) and notifying the parent process about the cause
+  of termination.
+- On POSIX systems, we now ignore `SIGPIPE` signals, use `-d:nimLegacySigpipeHandler`
+  for previous behavior.
+- Added `posix_utils.osReleaseFile` to get system identification from `os-release`
+  file on Linux and the BSDs.
+  ([link](https://www.freedesktop.org/software/systemd/man/os-release.html))
+- Removed undefined behavior for `posix.open`.
+
+
+## `std/prelude`
+
+- `std/strformat` is now part of `include std/prelude`.
+- Added `std/sequtils` import to `std/prelude`.
+- `std/prelude` now works with the JS target.
+- `std/prelude` can now be used via `include std/prelude`, but `include prelude` still works.
+
+
+## String manipulation: `std/strformat`, `std/strbasics`
+
+- Added support for parenthesized expressions.
+- Added support for const strings instead of just string literals.
+- Added `std/strbasics` for high-performance string operations.
+- Added `strip`, `setSlice`, `add(a: var string, b: openArray[char])`.
+
+
+## `std/wrapnils`
+
+- `std/wrapnils` doesn't use `experimental:dotOperators` anymore, avoiding
+  issues like bug [#13063](https://github.com/nim-lang/Nim/issues/13063)
+  (which affected error messages) for modules importing `std/wrapnils`.
+- Added `??.` macro which returns an `Option`.
+- `std/wrapnils` can now be used to protect against `FieldDefect` errors in
+  case objects, generates optimal code (no overhead compared to manual
+  if-else branches), and preserves lvalue semantics which allows modifying
+  an expression.
+
+
+## Containers: `std/algorithm`, `std/lists`, `std/sequtils`, `std/options`, `std/packedsets`
+
+- Removed the optional `longestMatch` parameter of the `critbits._WithPrefix`
+  iterators (it never worked reliably).
+- Added `algorithm.merge`.
+- In `std/lists`: renamed `append` to `add` and retained `append` as an alias;
+  added `prepend` and `prependMoved` analogously to `add` and `addMoved`;
+  added `remove` for `SinglyLinkedList`s.
+- Added new operations for singly- and doubly linked lists: `lists.toSinglyLinkedList`
+  and `lists.toDoublyLinkedList` convert from `openArray`s; `lists.copy` implements
+  shallow copying; `lists.add` concatenates two lists - an O(1) variation that consumes
+  its argument, `addMoved`, is also supplied.
+  See PRs [#16362](https://github.com/nim-lang/Nim/pull/16362),
+  [#16536](https://github.com/nim-lang/Nim/pull/16536).
+- New module: `std/packedsets`.
+  Generalizes `std/intsets`, see PR [#15564](https://github.com/nim-lang/Nim/pull/15564).
+
+Compatibility notes:
+- Deprecated `sequtils.delete` and added an overload taking a `Slice` that raises
+  a defect if the slice is out of bounds, likewise with `strutils.delete`.
+- Deprecated `proc reversed*[T](a: openArray[T], first: Natural, last: int): seq[T]`
+  in `std/algorithm`.
+- `std/options` changed `$some(3)` to `"some(3)"` instead of `"Some(3)"`
+  and `$none(int)` to `"none(int)"` instead of `"None[int]"`.
+
+
+## `std/times`
+
+- Added `ZZZ` and `ZZZZ` patterns to `times.nim` `DateTime` parsing, to match time
+  zone offsets without colons, e.g. `UTC+7 -> +0700`.
+- Added `dateTime` and deprecated `initDateTime`.
+
+
+## `std/macros` and AST
+
+- New module `std/genasts`, see description above.
+- The required name of case statement macros for the experimental
+  `caseStmtMacros` feature has changed from `match` to `` `case` ``.
+- Tuple expressions are now parsed consistently as
+  `nnkTupleConstr` node. Will affect macros expecting nodes to be of `nnkPar`.
+- In `std/macros`, `treeRepr,lispRepr,astGenRepr` now represent SymChoice nodes
+  in a collapsed way.
+  Use `-d:nimLegacyMacrosCollapseSymChoice` to get the previous behavior.
+- Made custom op in `macros.quote` work for all statements.
+
+
+## `std/sugar`
+
+- Added `sugar.dumpToString` which improves on `sugar.dump`.
+- Added an overload for the `collect` macro that infers the container type based
+  on the syntax of the last expression. Works with std seqs, tables and sets.
+
+Compatibility notes:
+- Removed support for named procs in `sugar.=>`.
+
+
+## Parsing: `std/parsecfg`, `std/strscans`, `std/uri`
+
+- Added `sections` iterator in `parsecfg`.
+- `strscans.scanf` now supports parsing single characters.
+- Added `strscans.scanTuple` which uses `strscans.scanf` internally,
+  returning a tuple which can be unpacked for easier usage of `scanf`.
+- Added `decodeQuery` to `std/uri`.
+- `parseopt.initOptParser` has been made available and `parseopt` has been
+  added back to `std/prelude` for all backends. Previously `initOptParser` was
+  unavailable if the `std/os` module did not have `paramCount` or `paramStr`,
+  but the use of these in `initOptParser` were conditionally to the runtime
+  arguments passed to it, so `initOptParser` has been changed to raise
+  `ValueError` when the real command line is not available. `parseopt` was
+  previously excluded from `std/prelude` for JS, as it could not be imported.
+
+Compatibility notes:
+- Changed the behavior of `uri.decodeQuery` when there are unencoded `=`
+  characters in the decoded values. Prior versions would raise an error. This is
+  no longer the case to comply with the HTML spec and other languages'
+  implementations. Old behavior can be obtained with
+  `-d:nimLegacyParseQueryStrict`. `cgi.decodeData` which uses the same
+  underlying code is also updated the same way.
+
+
+## JS stdlib changes
+
+- Added `std/jsbigints` module, which provides arbitrary precision integers for the JS target.
+- Added `setCurrentException` for the JS backend.
+- `writeStackTrace` is available in the JS backend now.
+- Added `then`, `catch` to `std/asyncjs` for promise pipelining, for now hidden
+  behind `-d:nimExperimentalAsyncjsThen`.
+- Added `std/jsfetch` module [Fetch](https://developer.mozilla.org/docs/Web/API/Fetch_API)
+  wrapper for the JS target.
+- Added `std/jsheaders` module [Headers](https://developer.mozilla.org/en-US/docs/Web/API/Headers)
+  wrapper for the JS target.
+- Added `std/jsformdata` module [FormData](https://developer.mozilla.org/en-US/docs/Web/API/FormData)
+  wrapper for the JS target.
+- Added `jscore.debugger` to [call any available debugging functionality, such as breakpoints](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/debugger).
+- Added `jsconsole.dir`, `jsconsole.dirxml`, `jsconsole.timeStamp`.
+- Added dollar `$` and `len` for `jsre.RegExp`.
+- Added `jsconsole.jsAssert` for the JS target.
+- Added `**` to `std/jsffi`.
+- Added `copyWithin` [for `seq` and `array` for JS targets](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/copyWithin).
+- In `std/dom`, `Interval` is now a `ref object`, same as `Timeout`.
+  Definitions of `setTimeout`, `clearTimeout`, `setInterval`, `clearInterval` were updated.
+- Added `dom.scrollIntoView` proc with options.
+- Added `dom.setInterval`, `dom.clearInterval` overloads.
+- Merged `std/dom_extensions` into the `std/dom` module,
+  as it was a module with a single line, see RFC [#413](https://github.com/nim-lang/RFCs/issues/413).
+- `$` now gives more correct results on the JS backend.
+
+
+## JS compiler changes
+
+- `cstring` doesn't support the `[]=` operator anymore in the JS backend.
+- Array literals now use JS typed arrays when the corresponding JS typed array exists,
+  for example `[byte(1), 2, 3]` generates `new Uint8Array([1, 2, 3])`.
+
+
+## VM and nimscript backend
+
+- VM now supports `addr(mystring[ind])` (index + index assignment).
+- `nimscript` now handles `except Exception as e`.
+- `nil` dereference is not allowed at compile time. `cast[ptr int](nil)[]` is rejected at compile time.
+- `static[T]` now works better, refs [#17590](https://github.com/nim-lang/Nim/pull/17590),
+  [#15853](https://github.com/nim-lang/Nim/pull/15853).
+- `distinct T` conversions now work in VM.
+- `items(cstring)` now works in VM.
+- Fix `addr`, `len`, `high` in VM ([#16002](https://github.com/nim-lang/Nim/pull/16002),
+  [#16610](https://github.com/nim-lang/Nim/pull/16610)).
+- `std/cstrutils` now works in VM.
+
+
+## OS/platform-specific notes
+
+- Support for Apple silicon/M1.
+- Support for 32-bit RISC-V, refs [#16231](https://github.com/nim-lang/Nim/pull/16231).
+- Support for armv8l, refs [#18901](https://github.com/nim-lang/Nim/pull/18901).
+- Support for CROSSOS, refs [#18889](https://github.com/nim-lang/Nim/pull/18889).
+- The allocator for Nintendo Switch, which was nonfunctional because
+  of breaking changes in libnx, was removed, in favor of the new `-d:nimAllocPagesViaMalloc` option.
+- Allow reading parameters when compiling for Nintendo Switch.
+- `--nimcache` now correctly works in a cross-compilation setting.
+- Cross compilation targeting Windows was improved.
+- This now works from macOS/Linux: `nim r -d:mingw main`
+
+
+
+## Performance / memory optimizations
+
+- The comment field in PNode AST was moved to a side channel, reducing overall
+  memory usage during compilation by a factor 1.25x
+- `std/jsonutils` deserialization is now up to 20x faster.
+- `os.copyFile` is now 2.5x faster on macOS, by using `copyfile` from `copyfile.h`;
+  use `-d:nimLegacyCopyFile` for macOS < 10.5.
+- Float to string conversion is now 10x faster thanks to the Dragonbox algorithm,
+  with `-d:nimPreviewFloatRoundtrip`.
+- `newSeqWith` is 3x faster.
+- CI now supports batching (making Windows CI 2.3X faster).
+- Sets now uses the optimized `countSetBits` proc, see PR
+  [#17334](https://github.com/nim-lang/Nim/pull/17334).
+
+
+## Debugging
+
+- You can now enable/disable VM tracing in user code via `vmutils.vmTrace`.
+- `koch tools` now builds `bin/nim_dbg` which allows easy access to a debug version
+  of Nim without recompiling.
+- Added new module `compiler/debugutils` to help with debugging Nim compiler.
+- Renamed `-d:nimCompilerStackraceHints` to `-d:nimCompilerStacktraceHints` and
+  used it in more contexts; this flag which works in tandem with `--stackTraceMsgs`
+  to show user code context in compiler stacktraces.
+
+
+## Type system
+
+- `typeof(voidStmt)` now works and returns `void`.
+- `enum` values can now be overloaded. This needs to be enabled
+  via `{.experimental: "overloadableEnums".}`. We hope that this feature allows
+  for the development of more fluent (less ugly) APIs.
+  See RFC [#373](https://github.com/nim-lang/RFCs/issues/373) for more details.
+- A type conversion from one `enum` type to another now produces an `[EnumConv]` warning.
+  You should use `ord` (or `cast`, but the compiler won't help, if you misuse it) instead.
+  ```nim
+  type A = enum a1, a2
+  type B = enum b1, b2
+  echo a1.B # produces a warning
+  echo a1.ord.B # produces no warning
+  ```
+- A dangerous implicit conversion to `cstring` now triggers a `[CStringConv]` warning.
+  This warning will become an error in future versions! Use an explicit conversion
+  like `cstring(x)` in order to silence the warning.
+- There is a new warning for *any* type conversion to `enum` that can be enabled via
+  `.warning[AnyEnumConv]:on` or `--warning:AnyEnumConv:on`.
+- Reusing a type name in a different scope now works, refs [#17710](https://github.com/nim-lang/Nim/pull/17710).
+- Fixed implicit and explicit generics in procedures, refs [#18808](https://github.com/nim-lang/Nim/pull/18808).
+
+
+## New-style concepts
+
+Example:
+```nim
+type
+  Comparable = concept # no T, an atom
+    proc cmp(a, b: Self): int
+```
+The new design does not rely on `system.compiles` and may compile faster.
+See PR [#15251](https://github.com/nim-lang/Nim/pull/15251)
+and RFC [#168](https://github.com/nim-lang/RFCs/issues/168) for details.
+
+
+## Lexical / syntactic
+
+- Nim now supports a small subset of Unicode operators as operator symbols.
+  The supported symbols are: "∙ ∘ × ★ ⊗ ⊘ ⊙ ⊛ ⊠ ⊡ ∩ ∧ ⊓ ± ⊕ ⊖ ⊞ ⊟ ∪ ∨ ⊔".
+  To enable this feature, use `--experimental:unicodeOperators`. Note that due
+  to parser limitations you **cannot** enable this feature via a
+  pragma `{.experimental: "unicodeOperators".}` reliably, you need to enable
+  it via the command line or in a configuration file.
+- `var a {.foo.} = expr` now works inside templates (except when `foo` is overloaded).
+
+
+## Compiler messages, error messages, hints, warnings
+
+- Significant improvement to error messages involving effect mismatches,
+  see PRs [#18384](https://github.com/nim-lang/Nim/pull/18384),
+  [#18418](https://github.com/nim-lang/Nim/pull/18418).
+- Added `--declaredLocs` to show symbol declaration location in error messages.
+- Added `--spellSuggest` to show spelling suggestions on typos.
+- Added `--processing:dots|filenames|off` which customizes `hintProcessing`;
+  `--processing:filenames` shows which include/import modules are being compiled as an import stack.
+- `FieldDefect` messages now shows discriminant value + lineinfo, in all backends (C, JS, VM)
+- Added `--hintAsError` with similar semantics as `--warningAsError`.
+- Added `--unitsep:on|off` to control whether to add ASCII unit separator `\31`
+  before a newline for every generated message (potentially multiline),
+  so tooling can tell when messages start and end.
+- Added `--filenames:abs|canonical|legacyRelProj` which replaces `--listFullPaths:on|off`
+- `--hint:all:on|off` is now supported to select or deselect all hints; it
+  differs from `--hints:on|off` which acts as a (reversible) gate.
+  Likewise with `--warning:all:on|off`.
+- The style checking of the compiler now supports a `--styleCheck:usages` switch.
+  This switch enforces that every symbol is written as it was declared, not enforcing
+  the official Nim style guide. To be enabled, this has to be combined either
+  with `--styleCheck:error` or `--styleCheck:hint`.
+- Type mismatch errors now show more context, use `-d:nimLegacyTypeMismatch` for
+  previous behavior.
+- `typedesc[Foo]` now renders as such instead of `type Foo` in compiler messages.
+- `runnableExamples` now show originating location in stacktraces on failure.
+- `SuccessX` message now shows more useful information.
+- New `DuplicateModuleImport` warning; improved `UnusedImport` and
+  `XDeclaredButNotUsed` accuracy.
+
+Compatibility notes:
+- `--hint:CC` now prints to stderr (like all other hints) instead of stdout.
+
+
+## Building and running Nim programs, configuration system
+
+- JSON build instructions are now generated in `$nimcache/outFileBasename.json`
+  instead of `$nimcache/projectName.json`. This allows avoiding recompiling a
+  given project compiled with different options if the output file differs.
+- `--usenimcache` (implied by `nim r main`) now generates an output file that includes
+  a hash of some of the compilation options, which allows caching generated binaries:
+  ```bash
+    nim r main # recompiles
+    nim r -d:foo main # recompiles
+    nim r main # uses cached binary
+    nim r main arg1 arg2 # likewise (runtime arguments are irrelevant)
+  ```
+- `nim r` now supports cross compilation from unix to windows when specifying
+  `-d:mingw` by using Wine, e.g.:
+  `nim r --eval:'import os; echo "a" / "b"'` prints `a\b`.
+- `nim` can compile version 1.4.0 as follows:
+  `nim c --lib:lib --stylecheck:off -d:nimVersion140 compiler/nim`.
+  `-d:nimVersion140` is not needed for bootstrapping, only for building 1.4.0 from devel.
+- `nim e` now accepts arbitrary file extensions for the nimscript file,
+  although `.nims` is still the preferred extension in general.
+- The configuration subsystem now allows for `-d:release` and `-d:danger` to work as expected.
+  The downside is that these defines now have custom logic that doesn't apply for
+  other defines.
+
+
+## Multithreading
+
+- TLS: macOS now uses native TLS (`--tlsEmulation:off`). TLS now works with
+  `importcpp` non-POD types; such types must use `.cppNonPod` and
+  `--tlsEmulation:off`should be used.
+- Added `unsafeIsolate` and `extract` to `std/isolation`.
+- Added `std/tasks`, see description above.
+
+
+## Memory management
+
+- `--gc:arc` now bootstraps (PR [#17342](https://github.com/nim-lang/Nim/pull/17342)).
+- Lots of improvements to `gc:arc`, `gc:orc`, see PR
+  [#15697](https://github.com/nim-lang/Nim/pull/15697),
+  [#16849](https://github.com/nim-lang/Nim/pull/16849),
+  [#17993](https://github.com/nim-lang/Nim/pull/17993).
+- `--gc:orc` is now 10% faster than previously for common workloads.
+  If you have trouble with its changed behavior, compile with `-d:nimOldOrc`.
+- The `--gc:orc` algorithm was refined so that custom container types can participate in the
+  cycle collection process. See the documentation of `=trace` for more details.
+- On embedded devices `malloc` can now be used instead of `mmap` via `-d:nimAllocPagesViaMalloc`.
+  This is only supported for `--gc:orc` or `--gc:arc`.
+
+Compatibility notes:
+- `--newruntime` and `--refchecks` are deprecated,
+  use `--gc:arc`, `--gc:orc`, or `--gc:none` as appropriate instead.
+
+
+## Docgen
+
+- docgen: RST files can now use single backticks instead of double backticks and
+  correctly render in both `nim rst2html` (as before) as well as common tools rendering
+  RST directly (e.g. GitHub).
+  This is done by adding the `default-role:: code` directive inside the RST file
+  (which is now handled by `nim rst2html`).
+- Source+Edit links now appear on top of every docgen'd page when
+  `nim doc --git.url:url ...` is given.
+- Latex doc generation is revised: output `.tex` files should be compiled
+  by `xelatex` (not by `pdflatex` as before). Now default Latex settings
+  provide support for Unicode and better avoid margin overflows.
+  The minimum required version is TeXLive 2018 (or an equivalent MikTeX version).
+- The RST parser now supports footnotes, citations, admonitions, and short style
+  references with symbols.
+- The RST parser now supports Markdown table syntax.
+  Known limitations:
+  - cell alignment is not supported, i.e. alignment annotations in a delimiter
+    row (`:---`, `:--:`, `---:`) are ignored
+  - every table row must start with `|`, e.g. `| cell 1 | cell 2 |`.
+- Implemented `doc2tex` compiler command which converts documentation in
+  `.nim` files to Latex.
+- docgen now supports syntax highlighting for inline code.
+- docgen now supports same-line doc comments:
+  ```nim
+  func fn*(a: int): int = 42  ## Doc comment
+  ```
+- docgen now renders `deprecated` and other pragmas.
+- `runnableExamples` now works with templates and nested templates.
+- `runnableExamples: "-r:off"` now works for examples that should compile but not run.
+- `runnableExamples` now renders code verbatim, and produces correct code in all cases.
+- docgen now shows correct, canonical import paths in docs.
+- docgen now shows all routines in sidebar, and the proc signature is now shown in sidebar.
+
+
+## Effects and checks
+
+- Significant improvement to error messages involving effect mismatches
+- There is a new `cast` section `{.cast(uncheckedAssign).}: body` that disables some
+  compiler checks regarding `case objects`. This allows serialization libraries
+  to avoid ugly, non-portable solutions. See RFC
+  [#407](https://github.com/nim-lang/RFCs/issues/407) for more details.
+
+
+## Tools
+
+- Major improvements to `nimgrep`, see PR [#15612
+](https://github.com/nim-lang/Nim/pull/15612).
+- `fusion` is now un-bundled from Nim, `./koch fusion` will
+  install it via Nimble at a fixed hash.
+- `testament`: added `nimoutFull: bool` spec to compare full output of compiler
+  instead of a subset; many bugfixes to testament.
+
+
+## Misc/cleanups
+
+- Deprecated `TaintedString` and `--taintmode`.
+- Deprecated `--nilseqs` which is now a noop.
+- Added `-d:nimStrictMode` in CI in several places to ensure code doesn't have
+  certain hints/warnings.
+- Removed `.travis.yml`, `appveyor.yml.disabled`, `.github/workflows/ci.yml.disabled`.
+- `[skip ci]` now works in azure and CI pipelines, see detail in PR
+  [#17561](https://github.com/nim-lang/Nim/pull/17561).