.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>
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24 changed files with 405 additions and 71 deletions
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@ -66,6 +66,7 @@ type
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TEffects = object
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exc: PNode # stack of exceptions
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tags: PNode # list of tags
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forbids: PNode # list of tags
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bottom, inTryStmt, inExceptOrFinallyStmt, leftPartOfAsgn: int
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owner: PSym
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ownerModule: PSym
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@ -388,6 +389,12 @@ proc addTag(a: PEffects, e, comesFrom: PNode) =
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if sameType(aa[i].typ.skipTypes(skipPtrs), e.typ.skipTypes(skipPtrs)): return
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throws(a.tags, e, comesFrom)
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proc addNotTag(a: PEffects, e, comesFrom: PNode) =
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var aa = a.forbids
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for i in 0..<aa.len:
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if sameType(aa[i].typ.skipTypes(skipPtrs), e.typ.skipTypes(skipPtrs)): return
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throws(a.forbids, e, comesFrom)
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proc mergeRaises(a: PEffects, b, comesFrom: PNode) =
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if b.isNil:
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addRaiseEffect(a, createRaise(a.graph, comesFrom), comesFrom)
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@ -403,6 +410,7 @@ proc mergeTags(a: PEffects, b, comesFrom: PNode) =
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proc listEffects(a: PEffects) =
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for e in items(a.exc): message(a.config, e.info, hintUser, typeToString(e.typ))
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for e in items(a.tags): message(a.config, e.info, hintUser, typeToString(e.typ))
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for e in items(a.forbids): message(a.config, e.info, hintUser, typeToString(e.typ))
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#if a.maxLockLevel != 0:
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# message(e.info, hintUser, "lockLevel: " & a.maxLockLevel)
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@ -604,7 +612,7 @@ proc isOwnedProcVar(tracked: PEffects; n: PNode): bool =
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proc isNoEffectList(n: PNode): bool {.inline.} =
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assert n.kind == nkEffectList
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n.len == 0 or (n[tagEffects] == nil and n[exceptionEffects] == nil)
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n.len == 0 or (n[tagEffects] == nil and n[exceptionEffects] == nil and n[forbiddenEffects] == nil)
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proc isTrival(caller: PNode): bool {.inline.} =
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result = caller.kind == nkSym and caller.sym.magic in {mEqProc, mIsNil, mMove, mWasMoved, mSwap}
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@ -924,14 +932,17 @@ type
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oldLocked: int
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oldLockLevel: TLockLevel
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enforcedGcSafety, enforceNoSideEffects: bool
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oldExc, oldTags: int
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exc, tags: PNode
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oldExc, oldTags, oldForbids: int
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exc, tags, forbids: PNode
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proc createBlockContext(tracked: PEffects): PragmaBlockContext =
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var oldForbidsLen = 0
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if tracked.forbids != nil: oldForbidsLen = tracked.forbids.len
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result = PragmaBlockContext(oldLocked: tracked.locked.len,
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oldLockLevel: tracked.currLockLevel,
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enforcedGcSafety: false, enforceNoSideEffects: false,
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oldExc: tracked.exc.len, oldTags: tracked.tags.len)
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oldExc: tracked.exc.len, oldTags: tracked.tags.len,
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oldForbids: oldForbidsLen)
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proc applyBlockContext(tracked: PEffects, bc: PragmaBlockContext) =
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if bc.enforcedGcSafety: tracked.inEnforcedGcSafe = true
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@ -952,6 +963,10 @@ proc unapplyBlockContext(tracked: PEffects; bc: PragmaBlockContext) =
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setLen(tracked.tags.sons, bc.oldTags)
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for t in bc.tags:
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addTag(tracked, t, t)
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if bc.forbids != nil:
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setLen(tracked.forbids.sons, bc.oldForbids)
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for t in bc.forbids:
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addNotTag(tracked, t, t)
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proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
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case whichPragma(pragma)
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@ -966,6 +981,13 @@ proc castBlock(tracked: PEffects, pragma: PNode, bc: var PragmaBlockContext) =
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else:
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bc.tags = newNodeI(nkArgList, pragma.info)
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bc.tags.add n
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of wForbids:
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let n = pragma[1]
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if n.kind in {nkCurly, nkBracket}:
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bc.forbids = n
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else:
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bc.forbids = newNodeI(nkArgList, pragma.info)
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bc.forbids.add n
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of wRaises:
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let n = pragma[1]
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if n.kind in {nkCurly, nkBracket}:
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@ -1274,7 +1296,7 @@ proc subtypeRelation(g: ModuleGraph; spec, real: PNode): bool =
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proc checkRaisesSpec(g: ModuleGraph; emitWarnings: bool; spec, real: PNode, msg: string, hints: bool;
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effectPredicate: proc (g: ModuleGraph; a, b: PNode): bool {.nimcall.};
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hintsArg: PNode = nil) =
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hintsArg: PNode = nil; isForbids: bool = false) =
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# check that any real exception is listed in 'spec'; mark those as used;
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# report any unused exception
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var used = initIntSet()
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@ -1282,8 +1304,11 @@ proc checkRaisesSpec(g: ModuleGraph; emitWarnings: bool; spec, real: PNode, msg:
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block search:
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for s in 0..<spec.len:
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if effectPredicate(g, spec[s], r):
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if isForbids: break
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used.incl(s)
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break search
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if isForbids:
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break search
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# XXX call graph analysis would be nice here!
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pushInfoContext(g.config, spec.info)
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var rr = if r.kind == nkRaiseStmt: r[0] else: r
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@ -1312,6 +1337,10 @@ proc checkMethodEffects*(g: ModuleGraph; disp, branch: PSym) =
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if not isNil(tagsSpec):
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checkRaisesSpec(g, false, tagsSpec, actual[tagEffects],
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"can have an unlisted effect: ", hints=off, subtypeRelation)
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let forbidsSpec = effectSpec(p, wForbids)
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if not isNil(forbidsSpec):
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checkRaisesSpec(g, false, forbidsSpec, actual[tagEffects],
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"has an illegal effect: ", hints=off, subtypeRelation, isForbids=true)
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if sfThread in disp.flags and notGcSafe(branch.typ):
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localError(g.config, branch.info, "base method is GC-safe, but '$1' is not" %
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branch.name.s)
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@ -1349,6 +1378,12 @@ proc setEffectsForProcType*(g: ModuleGraph; t: PType, n: PNode; s: PSym = nil) =
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elif s != nil and (s.magic != mNone or {sfImportc, sfExportc} * s.flags == {sfImportc}):
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effects[tagEffects] = newNodeI(nkArgList, effects.info)
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let forbidsSpec = effectSpec(n, wForbids)
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if not isNil(forbidsSpec):
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effects[forbiddenEffects] = forbidsSpec
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elif s != nil and (s.magic != mNone or {sfImportc, sfExportc} * s.flags == {sfImportc}):
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effects[forbiddenEffects] = newNodeI(nkArgList, effects.info)
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let requiresSpec = propSpec(n, wRequires)
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if not isNil(requiresSpec):
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effects[requiresEffects] = requiresSpec
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@ -1365,6 +1400,7 @@ proc rawInitEffects(g: ModuleGraph; effects: PNode) =
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newSeq(effects.sons, effectListLen)
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effects[exceptionEffects] = newNodeI(nkArgList, effects.info)
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effects[tagEffects] = newNodeI(nkArgList, effects.info)
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effects[forbiddenEffects] = newNodeI(nkArgList, effects.info)
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effects[requiresEffects] = g.emptyNode
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effects[ensuresEffects] = g.emptyNode
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effects[pragmasEffects] = g.emptyNode
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@ -1374,6 +1410,7 @@ proc initEffects(g: ModuleGraph; effects: PNode; s: PSym; t: var TEffects; c: PC
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t.exc = effects[exceptionEffects]
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t.tags = effects[tagEffects]
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t.forbids = effects[forbiddenEffects]
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t.owner = s
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t.ownerModule = s.getModule
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t.init = @[]
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@ -1448,6 +1485,15 @@ proc trackProc*(c: PContext; s: PSym, body: PNode) =
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else:
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effects[tagEffects] = t.tags
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let forbidsSpec = effectSpec(p, wForbids)
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if not isNil(forbidsSpec):
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checkRaisesSpec(g, false, forbidsSpec, t.tags, "has an illegal effect: ",
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hints=off, subtypeRelation, isForbids=true)
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# after the check, use the formal spec:
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effects[forbiddenEffects] = forbidsSpec
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else:
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effects[forbiddenEffects] = t.forbids
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let requiresSpec = propSpec(p, wRequires)
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if not isNil(requiresSpec):
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effects[requiresEffects] = requiresSpec
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