[cfe-commits] [Patch] - Avoid duplicated visits to default arguments for class templates

[Yang Chen]

Hi,

Seems RecursiveASTVisitor has a bug which could cause duplicated visits 
to default arguments for a class template. For example, given the code 
below:

class X;
template<class T = X> class Y;
template<class T> class Y {};

The default argument 'X' will be visited twice. The attached patch fixed 
the problem. I also attached a small testcase. Thanks.

- Yang
Index: include/clang/AST/RecursiveASTVisitor.h
===================================================================
--- include/clang/AST/RecursiveASTVisitor.h     (revision 157548)
+++ include/clang/AST/RecursiveASTVisitor.h     (working copy)
@@ -1486,7 +1486,7 @@
     // D is the "T" in something like
     //   template <template <typename> class T> class container { };
     TRY_TO(TraverseDecl(D->getTemplatedDecl()));
-    if (D->hasDefaultArgument()) {
+    if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited()) {
       TRY_TO(TraverseTemplateArgumentLoc(D->getDefaultArgument()));
     }
     TRY_TO(TraverseTemplateParameterListHelper(D->getTemplateParameters()));
@@ -1496,7 +1496,7 @@
     // D is the "T" in something like "template<typename T> class vector;"
     if (D->getTypeForDecl())
       TRY_TO(TraverseType(QualType(D->getTypeForDecl(), 0)));
-    if (D->hasDefaultArgument())
+    if (D->hasDefaultArgument() && !D->defaultArgumentWasInherited())
       TRY_TO(TraverseTypeLoc(D->getDefaultArgumentInfo()->getTypeLoc()));
   })
 
Index: unittests/Tooling/RecursiveASTVisitorTest.cpp
===================================================================
--- unittests/Tooling/RecursiveASTVisitorTest.cpp       (revision 157548)
+++ unittests/Tooling/RecursiveASTVisitorTest.cpp       (working copy)
@@ -394,4 +394,13 @@
   EXPECT_TRUE(Visitor.runOver("int k = (4) + 9;\n"));
 }
 
+TEST(RecursiveASTVisitor, VisitsClassTemplateTypeParmDefaultArgument) {
+  TypeLocVisitor Visitor;
+  Visitor.ExpectMatch("class X", 2, 23);
+  EXPECT_TRUE(Visitor.runOver(
+    "class X;\n"
+    "template<typename T = X> class Y;\n"
+    "template<typename T> class Y {};\n"));
+}
+
 } // end namespace clang
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