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Suppress macro expansion of NULL in NULL warnings.

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For "int i = NULL;" we would produce:

null.cpp:5:11: warning: implicit conversion of NULL constant to integer [-Wconversion]
  int i = NULL;
      ~   ^~~~
null.cpp:1:14: note: expanded from macro 'NULL'
\#define NULL __null
              ^~~~~~

But we really shouldn't trace that macro expansion back into the header, yet we
still want macro back traces for code like this:

\#define FOO NULL
int i = FOO;

or

\#define FOO int i = NULL;
FOO

While providing appropriate tagging at different levels of the expansion, etc.

The included test case exercises these cases & does some basic validation (to
ensure we don't have macro expansion notes where we shouldn't, and do where we
should) - but doesn't go as far as to validate the source location/ranges
used in those notes and warnings.

llvm-svn: 152940
This commit is contained in:
David Blaikie 2012-03-16 20:30:12 +00:00
parent a144a1d736
commit ae12b18ad8
2 changed files with 17 additions and 2 deletions
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7
clang/lib/Sema/SemaChecking.cpp
View File

@ -4075,8 +4075,11 @@ void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
== Expr::NPCK_GNUNull) && Target->isIntegerType()) {
S.Diag(E->getExprLoc(), diag::warn_impcast_null_pointer_to_integer)
<< T << E->getSourceRange() << clang::SourceRange(CC);
SourceLocation Loc = E->getSourceRange().getBegin();
if (Loc.isMacroID())
Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
<< T << Loc << clang::SourceRange(CC);
return;
}

12
clang/test/SemaCXX/conversion.cpp
View File

@ -1,4 +1,5 @@
// RUN: %clang_cc1 -triple x86_64-apple-darwin -fsyntax-only -Wconversion -verify %s
// RUN: %clang_cc1 -triple x86_64-apple-darwin -fsyntax-only -Wconversion %s 2>&1 | FileCheck %s
#include <stddef.h>
@ -68,4 +69,15 @@ void test3() {
char ch = NULL; // expected-warning {{implicit conversion of NULL constant to 'char'}}
unsigned char uch = NULL; // expected-warning {{implicit conversion of NULL constant to 'unsigned char'}}
short sh = NULL; // expected-warning {{implicit conversion of NULL constant to 'short'}}
// Use FileCheck to ensure we don't get any unnecessary macro-expansion notes
// (that don't appear as 'real' notes & can't be seen/tested by -verify)
// CHECK-NOT: note:
// CHECK: note: expanded from macro 'FNULL'
#define FNULL NULL
int a2 = FNULL; // expected-warning {{implicit conversion of NULL constant to 'int'}}
// CHECK-NOT: note:
// CHECK: note: expanded from macro 'FINIT'
#define FINIT int a3 = NULL;
FINIT // expected-warning {{implicit conversion of NULL constant to 'int'}}
}