[clang] [clang] Ignore GCC 11 `[[malloc(x)]]` attribute (PR #68059)

[Erich Keane via cfe-commits]

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@@ -2064,13 +2064,87 @@ static void handleTLSModelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 
 static void handleRestrictAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   QualType ResultType = getFunctionOrMethodResultType(D);
-  if (ResultType->isAnyPointerType() || ResultType->isBlockPointerType()) {
+  if (!ResultType->isAnyPointerType() && !ResultType->isBlockPointerType()) {
+    S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
+        << AL << getFunctionOrMethodResultSourceRange(D);
+    return;
+  }
+
+  if (AL.getNumArgs() == 0) {
     D->addAttr(::new (S.Context) RestrictAttr(S.Context, AL));
     return;
   }
 
-  S.Diag(AL.getLoc(), diag::warn_attribute_return_pointers_only)
-      << AL << getFunctionOrMethodResultSourceRange(D);
+  if (AL.getAttributeSpellingListIndex() == RestrictAttr::Declspec_restrict) {
+    // __declspec(restrict) accepts no arguments
+    S.Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 0;
+    return;
+  }
+
+  // [[gnu::malloc(deallocator)]] with args specifies a deallocator function
+  Expr *DeallocE = AL.getArgAsExpr(0);
+  SourceLocation DeallocLoc = DeallocE->getExprLoc();
+  FunctionDecl *DeallocFD = nullptr;
+  DeclarationNameInfo DeallocNI;
+
+  if (auto *DRE = dyn_cast<DeclRefExpr>(DeallocE)) {
+    DeallocFD = dyn_cast<FunctionDecl>(DRE->getDecl());
+    DeallocNI = DRE->getNameInfo();
+    if (!DeallocFD) {
+      S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function)
+          << 1 << DeallocNI.getName();
+      return;
+    }
+  } else if (auto *ULE = dyn_cast<UnresolvedLookupExpr>(DeallocE)) {
+    DeallocFD = S.ResolveSingleFunctionTemplateSpecialization(ULE, true);
+    DeallocNI = ULE->getNameInfo();
+    if (!DeallocFD) {
+      S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function)
+          << 2 << DeallocNI.getName();
+      if (ULE->getType() == S.Context.OverloadTy)
+        S.NoteAllOverloadCandidates(ULE);
+      return;
+    }
+  } else {
+    S.Diag(DeallocLoc, diag::err_attribute_malloc_arg_not_function) << 0;
+    return;
+  }
+
+  // 2nd arg of [[gnu::malloc(deallocator, 2)]] with args specifies the param
+  // of deallocator that deallocates the pointer (defaults to 1)
+  ParamIdx DeallocPtrIdx;
+  if (AL.getNumArgs() == 1) {
+    DeallocPtrIdx = ParamIdx(1, DeallocFD);
+
+    if (!DeallocPtrIdx.isValid() ||
+        !getFunctionOrMethodParamType(DeallocFD, DeallocPtrIdx.getASTIndex())
+             .getCanonicalType()
+             ->isPointerType()) {
+      S.Diag(DeallocLoc,
+             diag::err_attribute_malloc_arg_not_function_with_pointer_arg)
+          << DeallocNI.getName();
+      return;
+    }
+  } else {
+    if (!checkFunctionOrMethodParameterIndex(S, DeallocFD, AL, 2,
+                                             AL.getArgAsExpr(1), DeallocPtrIdx,
+                                             /* CanIndexImplicitThis=*/false))
+      return;
+
+    QualType DeallocPtrArgType =
+        getFunctionOrMethodParamType(DeallocFD, DeallocPtrIdx.getASTIndex());
+    if (!DeallocPtrArgType.getCanonicalType()->isPointerType()) {
+      S.Diag(DeallocLoc,
+             diag::err_attribute_malloc_arg_refers_to_non_pointer_type)
+          << DeallocPtrIdx.getSourceIndex() << DeallocPtrArgType
+          << DeallocNI.getName();
+      return;
+    }
+  }
+
+  // FIXME: we should add this attribute to Clang's AST, so that clang-analyzer
----------------
erichkeane wrote:

I think we SHOULD still add this to the AST anyway, as it represents code still.  However we should teach `CGCall.cpp` to no longer emit the 'no-alias'.

https://github.com/llvm/llvm-project/pull/68059