[clang] 447ea9b - [AST] default implementation is possible for non-member functions in C++20.

[Haojian Wu via cfe-commits]

Author: mydeveloperday
Date: 2020-05-25T10:45:12+02:00
New Revision: 447ea9b4f5f562c8fab7d11ecbb10ecd33155d5b

URL: https://github.com/llvm/llvm-project/commit/447ea9b4f5f562c8fab7d11ecbb10ecd33155d5b
DIFF: https://github.com/llvm/llvm-project/commit/447ea9b4f5f562c8fab7d11ecbb10ecd33155d5b.diff

LOG: [AST] default implementation is possible for non-member functions in C++20.

Summary:
Make RAV not visit the default function decl by default.
Also update some stale comments on FunctionDecl::isDefault.

Fixes https://github.com/clangd/clangd/issues/383

Reviewers: sammccall, rsmith

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D80288

Added: 
    

Modified: 
    clang/include/clang/AST/Decl.h
    clang/include/clang/AST/RecursiveASTVisitor.h
    clang/unittests/Tooling/RecursiveASTVisitorTests/CXXMethodDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index d7136a4cd420..2e1630827cce 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -2125,19 +2125,17 @@ class FunctionDecl : public DeclaratorDecl,
   bool isTrivialForCall() const { return FunctionDeclBits.IsTrivialForCall; }
   void setTrivialForCall(bool IT) { FunctionDeclBits.IsTrivialForCall = IT; }
 
-  /// Whether this function is defaulted per C++0x. Only valid for
-  /// special member functions.
+  /// Whether this function is defaulted. Valid for e.g.
+  /// special member functions, defaulted comparisions (not methods!).
   bool isDefaulted() const { return FunctionDeclBits.IsDefaulted; }
   void setDefaulted(bool D = true) { FunctionDeclBits.IsDefaulted = D; }
 
-  /// Whether this function is explicitly defaulted per C++0x. Only valid
-  /// for special member functions.
+  /// Whether this function is explicitly defaulted.
   bool isExplicitlyDefaulted() const {
     return FunctionDeclBits.IsExplicitlyDefaulted;
   }
 
-  /// State that this function is explicitly defaulted per C++0x. Only valid
-  /// for special member functions.
+  /// State that this function is explicitly defaulted.
   void setExplicitlyDefaulted(bool ED = true) {
     FunctionDeclBits.IsExplicitlyDefaulted = ED;
   }

diff  --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index a264d1cf24b2..b30d456bd24a 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2103,11 +2103,11 @@ bool RecursiveASTVisitor<Derived>::TraverseFunctionHelper(FunctionDecl *D) {
     }
   }
 
-  bool VisitBody = D->isThisDeclarationADefinition();
-  // If a method is set to default outside the class definition the compiler
-  // generates the method body and adds it to the AST.
-  if (const auto *MD = dyn_cast<CXXMethodDecl>(D))
-    VisitBody &= !MD->isDefaulted() || getDerived().shouldVisitImplicitCode();
+  bool VisitBody =
+      D->isThisDeclarationADefinition() &&
+      // Don't visit the function body if the function definition is generated
+      // by clang.
+      (!D->isDefaulted() || getDerived().shouldVisitImplicitCode());
 
   if (VisitBody) {
     TRY_TO(TraverseStmt(D->getBody())); // Function body.

diff  --git a/clang/unittests/Tooling/RecursiveASTVisitorTests/CXXMethodDecl.cpp b/clang/unittests/Tooling/RecursiveASTVisitorTests/CXXMethodDecl.cpp
index 6441ea99dd2c..90fa84bd4481 100644
--- a/clang/unittests/Tooling/RecursiveASTVisitorTests/CXXMethodDecl.cpp
+++ b/clang/unittests/Tooling/RecursiveASTVisitorTests/CXXMethodDecl.cpp
@@ -55,4 +55,22 @@ TEST(RecursiveASTVisitor, CXXMethodDeclNoDefaultBodyVisited) {
     EXPECT_TRUE(Visitor.runOver(Code, CXXMethodDeclVisitor::Lang_CXX11));
   }
 }
+
+TEST(RecursiveASTVisitor, FunctionDeclNoDefaultBodyVisited) {
+  for (bool VisitImplCode : {false, true}) {
+    CXXMethodDeclVisitor Visitor(VisitImplCode);
+    if (VisitImplCode)
+      Visitor.ExpectMatch("declref", 4, 58, /*Times=*/2);
+    else
+      Visitor.DisallowMatch("declref", 4, 58);
+    llvm::StringRef Code = R"cpp(
+      struct s {
+        int x;
+        friend auto operator==(s a, s b) -> bool = default;
+      };
+      bool k = s() == s(); // make sure clang generates the "==" definition.
+    )cpp";
+    EXPECT_TRUE(Visitor.runOver(Code, CXXMethodDeclVisitor::Lang_CXX2a));
+  }
+}
 } // end anonymous namespace