This patch implements as much of the narrowing conversion error specified by
[dcl.init.list] as is possible without generalized initializer lists or full
constant expression support, and adds a c++0x-compat warning in C++98 mode.
The FixIt currently uses a typedef's basename without qualification, which is
likely to be incorrect on some code. If it's incorrect on too much code, we
should write a function to get the string that refers to a type from a
particular context.
The warning is currently off by default. I'll fix LLVM and clang before turning
it on.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136181 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 78eb6d3..adf88c6 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -24,6 +24,7 @@
#include "clang/AST/ExprObjC.h"
#include "clang/AST/TypeLoc.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include <map>
using namespace clang;
@@ -778,7 +779,8 @@
// We cannot initialize this element, so let
// PerformCopyInitialization produce the appropriate diagnostic.
SemaRef.PerformCopyInitialization(Entity, SourceLocation(),
- SemaRef.Owned(expr));
+ SemaRef.Owned(expr),
+ /*TopLevelOfInitList=*/true);
hadError = true;
++Index;
++StructuredIndex;
@@ -820,7 +822,8 @@
ExprResult Result =
SemaRef.PerformCopyInitialization(Entity, expr->getLocStart(),
- SemaRef.Owned(expr));
+ SemaRef.Owned(expr),
+ /*TopLevelOfInitList=*/true);
Expr *ResultExpr = 0;
@@ -859,7 +862,8 @@
ExprResult Result =
SemaRef.PerformCopyInitialization(Entity, expr->getLocStart(),
- SemaRef.Owned(expr));
+ SemaRef.Owned(expr),
+ /*TopLevelOfInitList=*/true);
if (Result.isInvalid())
hadError = true;
@@ -908,7 +912,8 @@
if (!isa<InitListExpr>(Init) && Init->getType()->isVectorType()) {
ExprResult Result =
SemaRef.PerformCopyInitialization(Entity, Init->getLocStart(),
- SemaRef.Owned(Init));
+ SemaRef.Owned(Init),
+ /*TopLevelOfInitList=*/true);
Expr *ResultExpr = 0;
if (Result.isInvalid())
@@ -2197,6 +2202,158 @@
return !Steps.empty() && Steps.back().Kind == SK_ConstructorInitialization;
}
+bool InitializationSequence::endsWithNarrowing(ASTContext &Ctx,
+ const Expr *Initializer,
+ bool *isInitializerConstant,
+ APValue *ConstantValue) const {
+ if (Steps.empty() || Initializer->isValueDependent())
+ return false;
+
+ const Step &LastStep = Steps.back();
+ if (LastStep.Kind != SK_ConversionSequence)
+ return false;
+
+ const ImplicitConversionSequence &ICS = *LastStep.ICS;
+ const StandardConversionSequence *SCS = NULL;
+ switch (ICS.getKind()) {
+ case ImplicitConversionSequence::StandardConversion:
+ SCS = &ICS.Standard;
+ break;
+ case ImplicitConversionSequence::UserDefinedConversion:
+ SCS = &ICS.UserDefined.After;
+ break;
+ case ImplicitConversionSequence::AmbiguousConversion:
+ case ImplicitConversionSequence::EllipsisConversion:
+ case ImplicitConversionSequence::BadConversion:
+ return false;
+ }
+
+ // Check if SCS represents a narrowing conversion, according to C++0x
+ // [dcl.init.list]p7:
+ //
+ // A narrowing conversion is an implicit conversion ...
+ ImplicitConversionKind PossibleNarrowing = SCS->Second;
+ QualType FromType = SCS->getToType(0);
+ QualType ToType = SCS->getToType(1);
+ switch (PossibleNarrowing) {
+ // * from a floating-point type to an integer type, or
+ //
+ // * from an integer type or unscoped enumeration type to a floating-point
+ // type, except where the source is a constant expression and the actual
+ // value after conversion will fit into the target type and will produce
+ // the original value when converted back to the original type, or
+ case ICK_Floating_Integral:
+ if (FromType->isRealFloatingType() && ToType->isIntegralType(Ctx)) {
+ *isInitializerConstant = false;
+ return true;
+ } else if (FromType->isIntegralType(Ctx) && ToType->isRealFloatingType()) {
+ llvm::APSInt IntConstantValue;
+ if (Initializer &&
+ Initializer->isIntegerConstantExpr(IntConstantValue, Ctx)) {
+ // Convert the integer to the floating type.
+ llvm::APFloat Result(Ctx.getFloatTypeSemantics(ToType));
+ Result.convertFromAPInt(IntConstantValue, IntConstantValue.isSigned(),
+ llvm::APFloat::rmNearestTiesToEven);
+ // And back.
+ llvm::APSInt ConvertedValue = IntConstantValue;
+ bool ignored;
+ Result.convertToInteger(ConvertedValue,
+ llvm::APFloat::rmTowardZero, &ignored);
+ // If the resulting value is different, this was a narrowing conversion.
+ if (IntConstantValue != ConvertedValue) {
+ *isInitializerConstant = true;
+ *ConstantValue = APValue(IntConstantValue);
+ return true;
+ }
+ } else {
+ // Variables are always narrowings.
+ *isInitializerConstant = false;
+ return true;
+ }
+ }
+ return false;
+
+ // * from long double to double or float, or from double to float, except
+ // where the source is a constant expression and the actual value after
+ // conversion is within the range of values that can be represented (even
+ // if it cannot be represented exactly), or
+ case ICK_Floating_Conversion:
+ if (1 == Ctx.getFloatingTypeOrder(FromType, ToType)) {
+ // FromType is larger than ToType.
+ Expr::EvalResult InitializerValue;
+ // FIXME: Check whether Initializer is a constant expression according
+ // to C++0x [expr.const], rather than just whether it can be folded.
+ if (Initializer->Evaluate(InitializerValue, Ctx) &&
+ !InitializerValue.HasSideEffects && InitializerValue.Val.isFloat()) {
+ // Constant! (Except for FIXME above.)
+ llvm::APFloat FloatVal = InitializerValue.Val.getFloat();
+ // Convert the source value into the target type.
+ bool ignored;
+ llvm::APFloat::opStatus ConvertStatus = FloatVal.convert(
+ Ctx.getFloatTypeSemantics(ToType),
+ llvm::APFloat::rmNearestTiesToEven, &ignored);
+ // If there was no overflow, the source value is within the range of
+ // values that can be represented.
+ if (ConvertStatus & llvm::APFloat::opOverflow) {
+ *isInitializerConstant = true;
+ *ConstantValue = InitializerValue.Val;
+ return true;
+ }
+ } else {
+ *isInitializerConstant = false;
+ return true;
+ }
+ }
+ return false;
+
+ // * from an integer type or unscoped enumeration type to an integer type
+ // that cannot represent all the values of the original type, except where
+ // the source is a constant expression and the actual value after
+ // conversion will fit into the target type and will produce the original
+ // value when converted back to the original type.
+ case ICK_Integral_Conversion: {
+ assert(FromType->isIntegralOrUnscopedEnumerationType());
+ assert(ToType->isIntegralOrUnscopedEnumerationType());
+ const bool FromSigned = FromType->isSignedIntegerOrEnumerationType();
+ const unsigned FromWidth = Ctx.getIntWidth(FromType);
+ const bool ToSigned = ToType->isSignedIntegerOrEnumerationType();
+ const unsigned ToWidth = Ctx.getIntWidth(ToType);
+
+ if (FromWidth > ToWidth ||
+ (FromWidth == ToWidth && FromSigned != ToSigned)) {
+ // Not all values of FromType can be represented in ToType.
+ llvm::APSInt InitializerValue;
+ if (Initializer->isIntegerConstantExpr(InitializerValue, Ctx)) {
+ *isInitializerConstant = true;
+ *ConstantValue = APValue(InitializerValue);
+
+ // Add a bit to the InitializerValue so we don't have to worry about
+ // signed vs. unsigned comparisons.
+ InitializerValue = InitializerValue.extend(
+ InitializerValue.getBitWidth() + 1);
+ // Convert the initializer to and from the target width and signed-ness.
+ llvm::APSInt ConvertedValue = InitializerValue;
+ ConvertedValue = ConvertedValue.trunc(ToWidth);
+ ConvertedValue.setIsSigned(ToSigned);
+ ConvertedValue = ConvertedValue.extend(InitializerValue.getBitWidth());
+ ConvertedValue.setIsSigned(InitializerValue.isSigned());
+ // If the result is different, this was a narrowing conversion.
+ return ConvertedValue != InitializerValue;
+ } else {
+ // Variables are always narrowings.
+ *isInitializerConstant = false;
+ return true;
+ }
+ }
+ return false;
+ }
+
+ default:
+ // Other kinds of conversions are not narrowings.
+ return false;
+ }
+}
+
void InitializationSequence::AddAddressOverloadResolutionStep(
FunctionDecl *Function,
DeclAccessPair Found) {
@@ -4972,6 +5129,51 @@
dump(llvm::errs());
}
+static void DiagnoseNarrowingInInitList(
+ Sema& S, QualType EntityType, const Expr *InitE,
+ bool Constant, const APValue &ConstantValue) {
+ if (Constant) {
+ S.Diag(InitE->getLocStart(),
+ S.getLangOptions().CPlusPlus0x
+ ? diag::err_init_list_constant_narrowing
+ : diag::warn_init_list_constant_narrowing)
+ << InitE->getSourceRange()
+ << ConstantValue
+ << EntityType;
+ } else
+ S.Diag(InitE->getLocStart(),
+ S.getLangOptions().CPlusPlus0x
+ ? diag::err_init_list_variable_narrowing
+ : diag::warn_init_list_variable_narrowing)
+ << InitE->getSourceRange()
+ << InitE->getType()
+ << EntityType;
+
+ llvm::SmallString<128> StaticCast;
+ llvm::raw_svector_ostream OS(StaticCast);
+ OS << "static_cast<";
+ if (const TypedefType *TT = EntityType->getAs<TypedefType>()) {
+ // It's important to use the typedef's name if there is one so that the
+ // fixit doesn't break code using types like int64_t.
+ //
+ // FIXME: This will break if the typedef requires qualification. But
+ // getQualifiedNameAsString() includes non-machine-parsable components.
+ OS << TT->getDecl();
+ } else if (const BuiltinType *BT = EntityType->getAs<BuiltinType>())
+ OS << BT->getName(S.getLangOptions());
+ else {
+ // Oops, we didn't find the actual type of the variable. Don't emit a fixit
+ // with a broken cast.
+ return;
+ }
+ OS << ">(";
+ S.Diag(InitE->getLocStart(), diag::note_init_list_narrowing_override)
+ << InitE->getSourceRange()
+ << FixItHint::CreateInsertion(InitE->getLocStart(), OS.str())
+ << FixItHint::CreateInsertion(
+ S.getPreprocessor().getLocForEndOfToken(InitE->getLocEnd()), ")");
+}
+
//===----------------------------------------------------------------------===//
// Initialization helper functions
//===----------------------------------------------------------------------===//
@@ -4993,7 +5195,8 @@
ExprResult
Sema::PerformCopyInitialization(const InitializedEntity &Entity,
SourceLocation EqualLoc,
- ExprResult Init) {
+ ExprResult Init,
+ bool TopLevelOfInitList) {
if (Init.isInvalid())
return ExprError();
@@ -5007,5 +5210,13 @@
EqualLoc);
InitializationSequence Seq(*this, Entity, Kind, &InitE, 1);
Init.release();
+
+ bool Constant = false;
+ APValue Result;
+ if (TopLevelOfInitList &&
+ Seq.endsWithNarrowing(Context, InitE, &Constant, &Result)) {
+ DiagnoseNarrowingInInitList(*this, Entity.getType(), InitE,
+ Constant, Result);
+ }
return Seq.Perform(*this, Entity, Kind, MultiExprArg(&InitE, 1));
}