[clang] nolock/noalloc attributes (PR #84983)

[via cfe-commits]

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@@ -4912,3 +4922,279 @@ void AutoType::Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context) {
   Profile(ID, Context, getDeducedType(), getKeyword(), isDependentType(),
           getTypeConstraintConcept(), getTypeConstraintArguments());
 }
+
+FunctionEffect::~FunctionEffect() = default;
+
+bool FunctionEffect::diagnoseConversion(bool Adding, QualType OldType,
+                                        FunctionEffectSet OldFX,
+                                        QualType NewType,
+                                        FunctionEffectSet NewFX) const {
+  return false;
+}
+
+bool FunctionEffect::diagnoseRedeclaration(bool Adding,
+                                           const FunctionDecl &OldFunction,
+                                           FunctionEffectSet OldFX,
+                                           const FunctionDecl &NewFunction,
+                                           FunctionEffectSet NewFX) const {
+  return false;
+}
+
+bool FunctionEffect::diagnoseMethodOverride(bool Adding,
+                                            const CXXMethodDecl &OldMethod,
+                                            FunctionEffectSet OldFX,
+                                            const CXXMethodDecl &NewMethod,
+                                            FunctionEffectSet NewFX) const {
+  return false;
+}
+
+bool FunctionEffect::canInferOnDecl(const Decl *Caller,
+                                    FunctionEffectSet CallerFX) const {
+  return false;
+}
+
+bool FunctionEffect::diagnoseFunctionCall(bool Direct, const Decl *Caller,
+                                          FunctionEffectSet CallerFX,
+                                          CalleeDeclOrType Callee,
+                                          FunctionEffectSet CalleeFX) const {
+  return false;
+}
+
+const NoLockNoAllocEffect &NoLockNoAllocEffect::nolock_instance() {
+  static NoLockNoAllocEffect global(kNoLockTrue, "nolock");
+  return global;
+}
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Sirraide wrote:

> another limitation of AttributedType is that it doesn't seem to hold anything more than the attribute kind

The attribute itself appears to usually be stored in an `AttributedTypeLoc` rather than as part of the type itself. 

> two bugs where the sugar gets stripped, e.g. on an auto lambda

It seems we’re taking care to try and preserve `AttributedType`s in several places, so that does sound like it might be a bug; we should probably fix those (unless there’s a good reason why we’re stripping the attributes there).

> I got some guidance that the `true` forms of the attributes made sense as part of the canonical type

I agree that that makes sense, yeah.

> Even if FunctionEffect turns out to be just some bits controlling details of the behavior, rather than a vtable, it's still attractive to me to encapsulate it into a uniqued object with methods, to centralize all those behaviors.

I’ll take another look at how it’s currently used; I’d also like to hear what other people (for instance Aaron) have to say about this; I already pinged him in one of the comments below that’s also about this.

https://github.com/llvm/llvm-project/pull/84983