FunctionDecl::getFunctionTypeLoc: ignore function type attributes (#118420)

Related to #118290.

---------

Co-authored-by: v01dxyz <v01dxyz@v01d.xyz>
Co-authored-by: Owen Anderson <resistor@mac.com>

clang-tools-extra/clangd/unittests/InlayHintTests.cpp

@@ -1577,19 +1577,21 @@ TEST(TypeHints, Aliased) {
 }
 
 TEST(TypeHints, CallingConvention) {
-  // Check that we don't crash for lambdas without a FunctionTypeLoc
+  // Check that we don't crash for lambdas with an annotation
   // https://github.com/clangd/clangd/issues/2223
-  std::string Code = R"cpp(
+  Annotations Source(R"cpp(
     void test() {
-      []() __cdecl {};
+      []($lambda[[)]]__cdecl {};
     }
-  )cpp";
-  TestTU TU = TestTU::withCode(Code);
+  )cpp");
+  TestTU TU = TestTU::withCode(Source.code());
   TU.ExtraArgs.push_back("--target=x86_64-w64-mingw32");
   TU.PredefineMacros = true; // for the __cdecl
   auto AST = TU.build();
 
-  EXPECT_THAT(hintsOfKind(AST, InlayHintKind::Type), IsEmpty());
+  EXPECT_THAT(
+      hintsOfKind(AST, InlayHintKind::Type),
+      ElementsAre(HintMatcher(ExpectedHint{"-> void", "lambda"}, Source)));
 }
 
 TEST(TypeHints, Decltype) {

clang/lib/AST/Decl.cpp

@@ -3910,8 +3910,25 @@ bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
 
 FunctionTypeLoc FunctionDecl::getFunctionTypeLoc() const {
   const TypeSourceInfo *TSI = getTypeSourceInfo();
-  return TSI ? TSI->getTypeLoc().IgnoreParens().getAs<FunctionTypeLoc>()
-             : FunctionTypeLoc();
+
+  if (!TSI)
+    return FunctionTypeLoc();
+
+  TypeLoc TL = TSI->getTypeLoc();
+  FunctionTypeLoc FTL;
+
+  while (!(FTL = TL.getAs<FunctionTypeLoc>())) {
+    if (const auto PTL = TL.getAs<ParenTypeLoc>())
+      TL = PTL.getInnerLoc();
+    else if (const auto ATL = TL.getAs<AttributedTypeLoc>())
+      TL = ATL.getEquivalentTypeLoc();
+    else if (const auto MQTL = TL.getAs<MacroQualifiedTypeLoc>())
+      TL = MQTL.getInnerLoc();
+    else
+      break;
+  }
+
+  return FTL;
 }
 
 SourceRange FunctionDecl::getReturnTypeSourceRange() const {

clang/unittests/AST/AttrTest.cpp

@@ -86,6 +86,23 @@ TEST(Attr, AnnotateType) {
     struct S { int mem; };
     int [[clang::annotate_type("int")]]
     S::* [[clang::annotate_type("ptr_to_mem")]] ptr_to_member = &S::mem;
+
+    // Function Type Attributes
+    __attribute__((noreturn)) int f_noreturn();
+    __attribute__((preserve_most)) int f_cc_preserve_most();
+
+    #define PRESERVE_MOST __attribute__((preserve_most))
+    PRESERVE_MOST int f_macro_attribue();
+
+    int (__attribute__((preserve_most)) f_paren_attribute)();
+
+    int (
+      PRESERVE_MOST
+      (
+        __attribute__((warn_unused_result))
+        (f_w_paren_and_attr)
+      )
+    ) ();
   )cpp");
 
   {
@@ -153,6 +170,67 @@ TEST(Attr, AnnotateType) {
     EXPECT_EQ(IntTL.getType(), AST->getASTContext().IntTy);
   }
 
+  {
+    const FunctionDecl *Func = getFunctionNode(AST.get(), "f_noreturn");
+    const FunctionTypeLoc FTL = Func->getFunctionTypeLoc();
+    const FunctionType *FT = FTL.getTypePtr();
+
+    EXPECT_TRUE(FT->getNoReturnAttr());
+  }
+
+  {
+    const FunctionDecl *Func = getFunctionNode(AST.get(), "f_cc_preserve_most");
+    const FunctionTypeLoc FTL = Func->getFunctionTypeLoc();
+    const FunctionType *FT = FTL.getTypePtr();
+
+    EXPECT_TRUE(FT->getCallConv() == CC_PreserveMost);
+  }
+
+  {
+    for (auto should_have_func_type_loc : {
+             "f_macro_attribue",
+             "f_paren_attribute",
+             "f_w_paren_and_attr",
+         }) {
+      llvm::errs() << "O: " << should_have_func_type_loc << "\n";
+      const FunctionDecl *Func =
+          getFunctionNode(AST.get(), should_have_func_type_loc);
+
+      EXPECT_TRUE(Func->getFunctionTypeLoc());
+    }
+  }
+
+  // The following test verifies getFunctionTypeLoc returns a type
+  // which takes into account the attribute (instead of only the nake
+  // type).
+  //
+  // This is hard to do with C/C++ because it seems using a function
+  // type attribute with a C/C++ function declaration only results
+  // with either:
+  //
+  // 1. It does NOT produce any AttributedType (for example it only
+  //   sets one flag of the FunctionType's ExtInfo, e.g. NoReturn).
+  // 2. It produces an AttributedType with modified type and
+  //   equivalent type that are equal (for example, that's what
+  //   happens with Calling Convention attributes).
+  //
+  // Fortunately, ObjC has one specific function type attribute that
+  // creates an AttributedType with different modified type and
+  // equivalent type.
+  auto AST_ObjC = buildASTFromCodeWithArgs(
+      R"objc(
+    __attribute__((ns_returns_retained)) id f();
+  )objc",
+      {"-fobjc-arc", "-fsyntax-only", "-fobjc-runtime=macosx-10.7"},
+      "input.mm");
+  {
+    const FunctionDecl *f = getFunctionNode(AST_ObjC.get(), "f");
+    const FunctionTypeLoc FTL = f->getFunctionTypeLoc();
+
+    const FunctionType *FT = FTL.getTypePtr();
+    EXPECT_TRUE(FT->getExtInfo().getProducesResult());
+  }
+
   // Test type annotation on an `__auto_type` type in C mode.
   AST = buildASTFromCodeWithArgs(R"c(
     __auto_type [[clang::annotate_type("auto")]] auto_var = 1;