Add some comments to the virtual work. Thanks to Doug Gregor for the review.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62012 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 0 deletions

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 1d09ea7110..e0b0b169a2 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -696,9 +696,13 @@ public:
 
   void setBody(Stmt *B) { Body = B; }
 
+  /// Whether this function is virtual, either by explicit marking, or by
+  /// overriding a virtual function. Only valid on C++ member functions.
   bool isVirtual() { return IsVirtual; }
   void setVirtual() { IsVirtual = true; }
 
+  /// Whether this virtual function is pure, i.e. makes the containing class
+  /// abstract.
   bool isPure() { return IsPure; }
   void setPure() { IsPure = true; }
 
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index ba4a47d63e..dcd378936a 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -615,6 +615,9 @@ Sema::ActOnCXXMemberDeclarator(Scope *S, AccessSpecifier AS, Declarator &D,
     } else {
       // not static member. perhaps virtual function?
       if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Member)) {
+        // With declarators parsed the way they are, the parser cannot
+        // distinguish between a normal initializer and a pure-specifier.
+        // Thus this grotesque test.
         IntegerLiteral *IL;
         if ((IL = dyn_cast<IntegerLiteral>(Init)) && IL->getValue() == 0 &&
             Context.getCanonicalType(IL->getType()) == Context.IntTy) {