Make RecursiveASTVisitor visit lambda capture initialization expressions

[mboehme]

Summary

Lambda capture initializations are part of the explicit source code and therefore should be visited by default but, so far, RecursiveASTVisitor does not visit them.

This appears to be an oversight. Because the lambda body needs custom handling (calling TraverseLambdaBody()), the DEF_TRAVERSE_STMT for LambdaExpr sets ShouldVisitChildren to false but then neglects to visit the lambda capture initializations. This patch adds code to visit the expressions associated with lambda capture initializations.

[klimek]

lg

[mboehme]

This was reverted in rL276759 because it broke modernize-loop-convert.

D22903 contains a fix for the modernize-loop-convert issue. Will re-submit this patch once D22903 has landed.

include/clang/AST/RecursiveASTVisitor.h

 
 // Walk only the visible parts of lambda expressions.
 DEF_TRAVERSE_STMT(LambdaExpr, {
   for (LambdaExpr::capture_iterator C = S->explicit_capture_begin(),
                                     CEnd = S->explicit_capture_end();
        C != CEnd; ++C) {
     TRY_TO(TraverseLambdaCapture(S, C));
   }
+  for (Expr *Init : S->capture_inits()) {
+    TRY_TO_TRAVERSE_OR_ENQUEUE_STMT(Init);
+  }
 
   TypeLoc TL = S->getCallOperator()->getTypeSourceInfo()->getTypeLoc();
   FunctionProtoTypeLoc Proto = TL.castAs<FunctionProtoTypeLoc>();
 
   if (S->hasExplicitParameters() && S->hasExplicitResultType()) {
     // Visit the whole type.
     TRY_TO(TraverseTypeLoc(TL));
   } else {

unittests/Tooling/RecursiveASTVisitorTestExprVisitor.cpp

 
 TEST(RecursiveASTVisitor, VisitsCallExpr) {
   DeclRefExprVisitor Visitor;
   Visitor.ExpectMatch("x", 1, 22);
   EXPECT_TRUE(Visitor.runOver(
     "void x(); void y() { x(); }"));
 }
 
+TEST(RecursiveASTVisitor, VisitsLambdaCaptureInit) {
+  DeclRefExprVisitor Visitor;
+  Visitor.ExpectMatch("i", 1, 20);
+  EXPECT_TRUE(Visitor.runOver(
+    "void f() { int i; [i]{}; };",
+    DeclRefExprVisitor::Lang_CXX11));
+}
+
 /* FIXME: According to Richard Smith this is a bug in the AST.
 TEST(RecursiveASTVisitor, VisitsBaseClassTemplateArgumentsInInstantiation) {
   DeclRefExprVisitor Visitor;
   Visitor.ExpectMatch("x", 3, 43);
   EXPECT_TRUE(Visitor.runOver(
     "template <typename T> void x();\n"
     "template <void (*T)()> class X {};\n"
     "template <typename T> class Y : public X< x<T> > {};\n"