Author: aaronballman
Date: Tue Dec 18 07:54:38 2018
New Revision: 349497
URL: http://llvm.org/viewvc/llvm-project?rev=349497&view=rev
Log:
Emit -Wformat properly for bit-field promotions.
Only explicitly look through integer and floating-point promotion where the
result type is actually a promotion, which is not always the case for
bit-fields in C.
Patch by Bevin Hansson.
Added:
cfe/trunk/test/Sema/format-strings-bitfield-promotion.c
cfe/trunk/test/Sema/format-strings-bitfield-promotion.cxx
Modified:
cfe/trunk/lib/Sema/SemaChecking.cpp
Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=349497&r1=349496&r2=349497&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Tue Dec 18 07:54:38 2018
@@ -7771,6 +7771,30 @@ shouldNotPrintDirectly(const ASTContext
return std::make_pair(QualType(), StringRef());
}
+/// Return true if \p ICE is an implicit argument promotion of an arithmetic
+/// type. Bit-field 'promotions' from a higher ranked type to a lower ranked
+/// type do not count.
+static bool
+isArithmeticArgumentPromotion(Sema &S, const ImplicitCastExpr *ICE) {
+ QualType From = ICE->getSubExpr()->getType();
+ QualType To = ICE->getType();
+ // It's an integer promotion if the destination type is the promoted
+ // source type.
+ if (ICE->getCastKind() == CK_IntegralCast &&
+ From->isPromotableIntegerType() &&
+ S.Context.getPromotedIntegerType(From) == To)
+ return true;
+ // Look through vector types, since we do default argument promotion for
+ // those in OpenCL.
+ if (const auto *VecTy = From->getAs<ExtVectorType>())
+ From = VecTy->getElementType();
+ if (const auto *VecTy = To->getAs<ExtVectorType>())
+ To = VecTy->getElementType();
+ // It's a floating promotion if the source type is a lower rank.
+ return ICE->getCastKind() == CK_FloatingCast &&
+ S.Context.getFloatingTypeOrder(From, To) < 0;
+}
+
bool
CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
const char *StartSpecifier,
@@ -7798,11 +7822,11 @@ CheckPrintfHandler::checkFormatExpr(cons
// Look through argument promotions for our error message's reported type.
// This includes the integral and floating promotions, but excludes array
- // and function pointer decay; seeing that an argument intended to be a
- // string has type 'char [6]' is probably more confusing than 'char *'.
+ // and function pointer decay (seeing that an argument intended to be a
+ // string has type 'char [6]' is probably more confusing than 'char *') and
+ // certain bitfield promotions (bitfields can be 'demoted' to a lesser type).
if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
- if (ICE->getCastKind() == CK_IntegralCast ||
- ICE->getCastKind() == CK_FloatingCast) {
+ if (isArithmeticArgumentPromotion(S, ICE)) {
E = ICE->getSubExpr();
ExprTy = E->getType();
Added: cfe/trunk/test/Sema/format-strings-bitfield-promotion.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/format-strings-bitfield-promotion.c?rev=349497&view=auto
==============================================================================
--- cfe/trunk/test/Sema/format-strings-bitfield-promotion.c (added)
+++ cfe/trunk/test/Sema/format-strings-bitfield-promotion.c Tue Dec 18 07:54:38
2018
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -fsyntax-only -verify %s
+
+int printf(const char *restrict, ...);
+
+struct bitfields {
+ long a : 2;
+ unsigned long b : 2;
+ long c : 32; // assumes that int is 32 bits
+ unsigned long d : 32; // assumes that int is 32 bits
+} bf;
+
+void bitfield_promotion() {
+ printf("%ld", bf.a); // expected-warning {{format specifies type 'long' but
the argument has type 'int'}}
+ printf("%lu", bf.b); // expected-warning {{format specifies type 'unsigned
long' but the argument has type 'int'}}
+ printf("%ld", bf.c); // expected-warning {{format specifies type 'long' but
the argument has type 'int'}}
+ printf("%lu", bf.d); // expected-warning {{format specifies type 'unsigned
long' but the argument has type 'unsigned int'}}
+}
Added: cfe/trunk/test/Sema/format-strings-bitfield-promotion.cxx
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/format-strings-bitfield-promotion.cxx?rev=349497&view=auto
==============================================================================
--- cfe/trunk/test/Sema/format-strings-bitfield-promotion.cxx (added)
+++ cfe/trunk/test/Sema/format-strings-bitfield-promotion.cxx Tue Dec 18
07:54:38 2018
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -fsyntax-only -verify %s
+
+// In C++, the bitfield promotion from long to int does not occur, unlike C.
+// expected-no-diagnostics
+
+int printf(const char *restrict, ...);
+
+struct bitfields {
+ long a : 2;
+ unsigned long b : 2;
+ long c : 32; // assumes that int is 32 bits
+ unsigned long d : 32; // assumes that int is 32 bits
+} bf;
+
+void bitfield_promotion() {
+ printf("%ld", bf.a);
+ printf("%lu", bf.b);
+ printf("%ld", bf.c);
+ printf("%lu", bf.d);
+}
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