.forbids pragma: defining forbidden tags (#20050)

* .forbids pragma: defining illegal effects for proc types

This patch intends to define the opposite of the .tags pragma: a way to define effects which are not allowed in a proc.

* updated documentation and changelogs for the forbids pragma

* renamed notTagEffects to forbiddenEffects

* corrected issues of forbids pragma

the forbids pragma didn't handle simple restrictions properly and it also had issues with subtyping

* removed incorrect character from changelog

* added test to cover the interaction of methods and the forbids pragma

* covering the interaction of the tags and forbids pragmas

* updated manual about the forbids pragma

* removed useless statement

* corrected the subtyping of proc types using the forbids pragma

* updated manual for the forbids pragma

* updated documentations for forbids pragma

* updated nim docs

* updated docs with rsttester.nim

* regenerated documentation

* updated rst docs

* Update changelog.md

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>

* updated changelog

* corrected typo

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/std/effecttraits.nim b/lib/std/effecttraits.nim
index 635ec82d0..fb057a669 100644
--- a/lib/std/effecttraits.nim
+++ b/lib/std/effecttraits.nim
@@ -18,6 +18,7 @@ import macros
 
 proc getRaisesListImpl(n: NimNode): NimNode = discard "see compiler/vmops.nim"
 proc getTagsListImpl(n: NimNode): NimNode = discard "see compiler/vmops.nim"
+proc getForbidsListImpl(n: NimNode): NimNode = discard "see compiler/vmops.nim"
 proc isGcSafeImpl(n: NimNode): bool = discard "see compiler/vmops.nim"
 proc hasNoSideEffectsImpl(n: NimNode): bool = discard "see compiler/vmops.nim"
 
@@ -37,6 +38,14 @@ proc getTagsList*(fn: NimNode): NimNode =
   expectKind fn, nnkSym
   result = getTagsListImpl(fn)
 
+proc getForbidsList*(fn: NimNode): NimNode =
+  ## Extracts the `.forbids` list of the func/proc/etc `fn`.
+  ## `fn` has to be a resolved symbol of kind `nnkSym`. This
+  ## implies that the macro that calls this proc should accept `typed`
+  ## arguments and not `untyped` arguments.
+  expectKind fn, nnkSym
+  result = getForbidsListImpl(fn)
+
 proc isGcSafe*(fn: NimNode): bool =
   ## Return true if the func/proc/etc `fn` is `gcsafe`.
   ## `fn` has to be a resolved symbol of kind `nnkSym`. This