From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 31 Jan 2013 01:34:31 +0000 (+0000)
Subject: Fix ODR-use of a MemberExpr to check before marking a pure function used. Remove
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4ceaf337be78fa89b4a97f351be6d0bda962d7de;p=clang

Fix ODR-use of a MemberExpr to check before marking a pure function used. Remove
a workaround for this bug from the -Wundefined-internals warning.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174020 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 5dc2a6a700..5764355144 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -396,7 +396,7 @@ static void checkUndefinedInternals(Sema &S) {
     if (decl->hasAttr<WeakRefAttr>()) continue;
 
     if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
-      if (fn->isPure() || fn->hasBody())
+      if (fn->isDefined())
         continue;
     } else {
       if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 60e104cadf..bfbb22ca08 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -10506,8 +10506,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func) {
   }
 
   // Keep track of used but undefined functions.
-  if (!Func->isPure() && !Func->hasBody() &&
-      Func->getLinkage() != ExternalLinkage) {
+  if (!Func->isDefined() && Func->getLinkage() != ExternalLinkage) {
     SourceLocation &old = UndefinedInternals[Func->getCanonicalDecl()];
     if (old.isInvalid()) old = Loc;
   }
@@ -11167,6 +11166,17 @@ void Sema::MarkDeclRefReferenced(DeclRefExpr *E) {
 
 /// \brief Perform reference-marking and odr-use handling for a MemberExpr.
 void Sema::MarkMemberReferenced(MemberExpr *E) {
+  // C++11 [basic.def.odr]p2
+  //   A non-overloaded function whose name appears as a potentially-evaluated
+  //   expression or a member of a set of candidate functions, if selected by
+  //   overload resolution when referred to from a potentially-evaluated
+  //   expression, is odr-used, unless it is a pure virtual function and its
+  //   name is not explicitly qualified.
+  if (!E->hasQualifier()) {
+    if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(E->getMemberDecl()))
+      if (Method->isPure())
+        return;
+  }
   MarkExprReferenced(*this, E->getMemberLoc(), E->getMemberDecl(), E);
 }
 
diff --git a/test/SemaCXX/undefined-internal.cpp b/test/SemaCXX/undefined-internal.cpp
index e8ee4c1e90..62c6ff96ca 100644
--- a/test/SemaCXX/undefined-internal.cpp
+++ b/test/SemaCXX/undefined-internal.cpp
@@ -199,3 +199,16 @@ namespace test8 {
     }
   } *A;
 }
+
+namespace test9 {
+  namespace {
+    struct X {
+      virtual void notused() = 0;
+      virtual void used() = 0; // expected-warning {{function 'test9::<anonymous namespace>::X::used' has internal linkage but is not defined}}
+    };
+  }
+  void test(X &x) {
+    x.notused();
+    x.X::used(); // expected-note {{used here}}
+  }
+}