From ff07af12df83c0112d702f61557bf9541584074f Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Mon, 12 Dec 2011 19:10:03 +0000
Subject: [PATCH] Clean up diagnostic wording for disallowed casts in C++11
 constant expressions.

llvm-svn: 146395
---
 clang/include/clang/Basic/DiagnosticASTKinds.td  |  4 ++--
 clang/lib/AST/ExprConstant.cpp                   |  9 +++++++--
 clang/test/SemaCXX/constant-expression-cxx11.cpp | 14 +++++++-------
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td b/clang/include/clang/Basic/DiagnosticASTKinds.td
index e16f768b2a9b..9f0da2d6eb72 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -13,8 +13,8 @@ let Component = "AST" in {
 //  "C does not permit evaluated commas in an integer constant expression">;
 def note_expr_divide_by_zero : Note<"division by zero">;
 def note_constexpr_invalid_cast : Note<
-  "%select{reinterpret_cast|dynamic_cast|reinterpreting cast}0 not allowed "
-  "in a constant expression">;
+  "%select{reinterpret_cast|dynamic_cast|cast interpreted as a "
+  "reinterpret_cast|cast from %1}0 is not allowed in a constant expression">;
 
 // inline asm related.
 let CategoryName = "Inline Assembly Issue" in {
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 62d70dd97828..3a897ab34842 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2226,8 +2226,13 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
     // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
     // permitted in constant expressions in C++11. Bitcasts from cv void* are
     // also static_casts, but we disallow them as a resolution to DR1312.
-    if (!E->getType()->isVoidPointerType())
-      CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
+    if (!E->getType()->isVoidPointerType()) {
+      if (SubExpr->getType()->isVoidPointerType())
+        CCEDiag(E, diag::note_constexpr_invalid_cast)
+          << 3 << SubExpr->getType();
+      else
+        CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
+    }
     if (!Visit(SubExpr))
       return false;
     Result.Designator.setInvalid();
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index 55762b4ea4ce..3ba76d42997c 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -301,25 +301,25 @@ struct Str {
   // FIXME: In C++ mode, we should say 'integral' not 'integer'
   int a : dynamic_cast<S*>(sptr) == dynamic_cast<S*>(sptr); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{dynamic_cast not allowed in a constant expression}}
+    expected-note {{dynamic_cast is not allowed in a constant expression}}
   int b : reinterpret_cast<S*>(sptr) == reinterpret_cast<S*>(sptr); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpret_cast not allowed in a constant expression}}
+    expected-note {{reinterpret_cast is not allowed in a constant expression}}
   int c : (S*)(long)(sptr) == (S*)(long)(sptr); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpreting cast not allowed in a constant expression}}
+    expected-note {{cast interpreted as a reinterpret_cast is not allowed in a constant expression}}
   int d : (S*)(42) == (S*)(42); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpreting cast not allowed in a constant expression}}
+    expected-note {{cast interpreted as a reinterpret_cast is not allowed in a constant expression}}
   int e : (Str*)(sptr) == (Str*)(sptr); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpreting cast not allowed in a constant expression}}
+    expected-note {{cast interpreted as a reinterpret_cast is not allowed in a constant expression}}
   int f : &(Str&)(*sptr) == &(Str&)(*sptr); // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpreting cast not allowed in a constant expression}}
+    expected-note {{cast interpreted as a reinterpret_cast is not allowed in a constant expression}}
   int g : (S*)(void*)(sptr) == sptr; // \
     expected-warning {{not integer constant expression}} \
-    expected-note {{reinterpreting cast not allowed in a constant expression}}
+    expected-note {{cast from 'void *' is not allowed in a constant expression}}
 };
 
 extern char externalvar[];