From 95f49fb26637e0f271bca580e8e20ce3c08ac2e9 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 3 Apr 2009 21:11:28 +0000
Subject: [PATCH] improve the string literal comparison warning to not call
 @encode's "string literals".

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68407 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Basic/DiagnosticSemaKinds.td | 4 ++--
 lib/Sema/SemaExpr.cpp                      | 4 +++-
 test/SemaObjC/exprs.m                      | 2 ++
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 0a53a65e13..815b8b5ae6 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1417,8 +1417,8 @@ def warn_ret_stack_ref : Warning<
 def warn_selfcomparison : Warning<
   "self-comparison always results in a constant value">;
 def warn_stringcompare : Warning<
-  "result of comparison against a string literal is unspecified "
-  "(use strcmp?)">;
+  "result of comparison against %select{a string literal|@encode}0 is "
+  "unspecified (use strcmp instead)">;
 
 
 
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index b3c8be49c9..55eaaa4bc8 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -3411,7 +3411,8 @@ QualType Sema::CheckCompareOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
     // operand is null), the user probably wants strcmp.
     if ((isa<StringLiteral>(LHSStripped) || isa<ObjCEncodeExpr>(LHSStripped)) &&
         !RHSStripped->isNullPointerConstant(Context))
-      Diag(Loc, diag::warn_stringcompare) 
+      Diag(Loc, diag::warn_stringcompare)
+        << isa<ObjCEncodeExpr>(LHSStripped)
         << lex->getSourceRange()
         << CodeModificationHint::CreateReplacement(SourceRange(Loc), ", ")
         << CodeModificationHint::CreateInsertion(lex->getLocStart(),
@@ -3423,6 +3424,7 @@ QualType Sema::CheckCompareOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
               isa<ObjCEncodeExpr>(RHSStripped)) &&
              !LHSStripped->isNullPointerConstant(Context))
       Diag(Loc, diag::warn_stringcompare) 
+        << isa<ObjCEncodeExpr>(RHSStripped)
         << rex->getSourceRange()
         << CodeModificationHint::CreateReplacement(SourceRange(Loc), ", ")
         << CodeModificationHint::CreateInsertion(lex->getLocStart(),
diff --git a/test/SemaObjC/exprs.m b/test/SemaObjC/exprs.m
index 342449d997..d51d135fa2 100644
--- a/test/SemaObjC/exprs.m
+++ b/test/SemaObjC/exprs.m
@@ -15,5 +15,7 @@ void test2() {
             "bar"
            @"baz"
            " b\0larg";  // expected-warning {{literal contains NUL character}}
+
   
+  if (@encode(int) == "foo") { }  // expected-warning {{result of comparison against @encode is unspecified}}
 }
-- 
2.40.0