diff options
| -rw-r--r-- | changelogs/changelog_2_0_0.md | 11 | ||||
| -rw-r--r-- | compiler/sempass2.nim | 3 | ||||
| -rw-r--r-- | compiler/semstmts.nim | 5 | ||||
| -rw-r--r-- | doc/destructors.md | 14 |
4 files changed, 26 insertions, 7 deletions
diff --git a/changelogs/changelog_2_0_0.md b/changelogs/changelog_2_0_0.md index 17f0fcfc4..8a5019731 100644 --- a/changelogs/changelog_2_0_0.md +++ b/changelogs/changelog_2_0_0.md @@ -179,7 +179,7 @@ for 64-bit integer types (`int64` and `uint64`) by default. As this affects JS code generation, code using these types to interface with the JS backend may need to be updated. Note that `int` and `uint` are not affected. - + For compatibility with [platforms that do not support BigInt](https://caniuse.com/bigint) and in the case of potential bugs with the new implementation, the old behavior is currently still supported with the command line option @@ -195,7 +195,7 @@ iterator iter(): int = yield 123 - + proc takesProc[T: proc](x: T) = discard proc takesIter[T: iterator](x: T) = discard @@ -221,10 +221,15 @@ - Signed integer literals in `set` literals now default to a range type of `0..255` instead of `0..65535` (the maximum size of sets). - + - Case statements with else branches put before elif/of branches in macros are rejected with "invalid order of case branches". +- Destructors now default to `.raises: []` (i.e. destructors must not raise + unlisted exceptions) and explicitly raising destructors are implementation + defined behavior. + + ## Standard library additions and changes [//]: # "Changes:" diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim index ce4febd3f..f0e55887c 100644 --- a/compiler/sempass2.nim +++ b/compiler/sempass2.nim @@ -1499,7 +1499,8 @@ proc trackProc*(c: PContext; s: PSym, body: PNode) = let p = s.ast[pragmasPos] let raisesSpec = effectSpec(p, wRaises) if not isNil(raisesSpec): - checkRaisesSpec(g, false, raisesSpec, t.exc, "can raise an unlisted exception: ", + let useWarning = s.name.s == "=destroy" + checkRaisesSpec(g, useWarning, raisesSpec, t.exc, "can raise an unlisted exception: ", hints=on, subtypeRelation, hintsArg=s.ast[0]) # after the check, use the formal spec: effects[exceptionEffects] = raisesSpec diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim index d493364ea..43d22bc55 100644 --- a/compiler/semstmts.nim +++ b/compiler/semstmts.nim @@ -1857,6 +1857,11 @@ proc semOverride(c: PContext, s: PSym, n: PNode) = case name of "=destroy": bindTypeHook(c, s, n, attachedDestructor) + if s.ast != nil: + if s.ast[pragmasPos].kind == nkEmpty: + s.ast[pragmasPos] = newNodeI(nkPragma, s.info) + s.ast[pragmasPos].add newTree(nkExprColonExpr, + newIdentNode(c.cache.getIdent("raises"), s.info), newNodeI(nkBracket, s.info)) of "deepcopy", "=deepcopy": if s.typ.len == 2 and s.typ[1].skipTypes(abstractInst).kind in {tyRef, tyPtr} and diff --git a/doc/destructors.md b/doc/destructors.md index a96ac35ef..a37eade33 100644 --- a/doc/destructors.md +++ b/doc/destructors.md @@ -13,12 +13,12 @@ Nim Destructors and Move Semantics About this document =================== -This document describes the upcoming Nim runtime which does +This document describes the ARC/ORC Nim runtime which does not use classical GC algorithms anymore but is based on destructors and -move semantics. The new runtime's advantages are that Nim programs become +move semantics. The advantages are that Nim programs become oblivious to the involved heap sizes and programs are easier to write to make effective use of multi-core machines. As a nice bonus, files and sockets and -the like will not require manual `close` calls anymore. +the like can be written not to require manual `close` calls anymore. This document aims to be a precise specification about how move semantics and destructors work in Nim. @@ -132,6 +132,14 @@ The general pattern in `=destroy` looks like: freeResource(x.field) ``` +A `=destroy` is implicitly annotated with `.raises: []`; a destructor +should not raise exceptions. For backwards compatibility the compiler +produces a warning for a `=destroy` that does raise. + +A `=destroy` can explicitly list the exceptions it can raise, if any, +but this of little utility as a raising destructor is implementation defined +behavior. Later versions of the language specification might cover this case precisely. + `=sink` hook ------------ |