r259947 will stop this warning on char arrays. On Mon, Feb 1, 2016 at 1:40 PM, Richard Trieu <rtr...@google.com> wrote:
> C++11 narrowing only happens during certain conversions while this warning > checks all conversions. > > We might be able to avoid char array initialization, but it would be a > little tricky. These warning usually have little information about where > the conversion is coming from, so distinguishing array initialization > versus variable initialization could be hard. > > On Sat, Jan 30, 2016 at 6:41 AM, Nico Weber <tha...@chromium.org> wrote: > >> Shouldn't the new case be in -Wc++11-narrowing instead? This is warning >> in similar places where that warning used to warn. >> >> In practice, char arrays seem to be often used for storing binary blobs >> in header files, and those are usually initialized with numbers 0...255 >> instead of -128...127 (why not make the array uint8_t then? Because maybe >> the function you want to pass the data from wants a char* array, and having >> to reinterpret_cast from uint8_t to char is annoying). Maybe this shouldn't >> fire for char arrays? >> >> On Fri, Jan 29, 2016 at 6:51 PM, Richard Trieu via cfe-commits < >> cfe-commits@lists.llvm.org> wrote: >> >>> Author: rtrieu >>> Date: Fri Jan 29 17:51:16 2016 >>> New Revision: 259271 >>> >>> URL: http://llvm.org/viewvc/llvm-project?rev=259271&view=rev >>> Log: >>> Improve -Wconstant-conversion >>> >>> Switch the evaluation from isIntegerConstantExpr to EvaluateAsInt. >>> EvaluateAsInt will evaluate more types of expressions than >>> isIntegerConstantExpr. >>> >>> Move one case from -Wsign-conversion to -Wconstant-conversion. The case >>> is: >>> 1) Source and target types are signed >>> 2) Source type is wider than the target type >>> 3) The source constant value is positive >>> 4) The conversion will store the value as negative in the target. >>> >>> Modified: >>> cfe/trunk/lib/Sema/SemaChecking.cpp >>> cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp >>> cfe/trunk/test/Sema/constant-conversion.c >>> >>> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=259271&r1=259270&r2=259271&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original) >>> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Jan 29 17:51:16 2016 >>> @@ -7578,7 +7578,7 @@ void CheckImplicitConversion(Sema &S, Ex >>> // If the source is a constant, use a default-on diagnostic. >>> // TODO: this should happen for bitfield stores, too. >>> llvm::APSInt Value(32); >>> - if (E->isIntegerConstantExpr(Value, S.Context)) { >>> + if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) { >>> if (S.SourceMgr.isInSystemMacro(CC)) >>> return; >>> >>> @@ -7603,6 +7603,42 @@ void CheckImplicitConversion(Sema &S, Ex >>> return DiagnoseImpCast(S, E, T, CC, >>> diag::warn_impcast_integer_precision); >>> } >>> >>> + if (TargetRange.Width == SourceRange.Width && >>> !TargetRange.NonNegative && >>> + SourceRange.NonNegative && Source->isSignedIntegerType()) { >>> + // Warn when doing a signed to signed conversion, warn if the >>> positive >>> + // source value is exactly the width of the target type, which will >>> + // cause a negative value to be stored. >>> + >>> + llvm::APSInt Value; >>> + if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) { >>> + if (!S.SourceMgr.isInSystemMacro(CC)) { >>> + >>> + IntegerLiteral *IntLit = >>> + dyn_cast<IntegerLiteral>(E->IgnoreParenImpCasts()); >>> + >>> + // If initializing from a constant, and the constant starts >>> with '0', >>> + // then it is a binary, octal, or hexadecimal. Allow these >>> constants >>> + // to fill all the bits, even if there is a sign change. >>> + if (!IntLit || >>> + >>> *(S.getSourceManager().getCharacterData(IntLit->getLocStart())) != >>> + '0') { >>> + >>> + std::string PrettySourceValue = Value.toString(10); >>> + std::string PrettyTargetValue = >>> + PrettyPrintInRange(Value, TargetRange); >>> + >>> + S.DiagRuntimeBehavior( >>> + E->getExprLoc(), E, >>> + S.PDiag(diag::warn_impcast_integer_precision_constant) >>> + << PrettySourceValue << PrettyTargetValue << >>> E->getType() << T >>> + << E->getSourceRange() << clang::SourceRange(CC)); >>> + return; >>> + } >>> + } >>> + } >>> + // Fall through for non-constants to give a sign conversion warning. >>> + } >>> + >>> if ((TargetRange.NonNegative && !SourceRange.NonNegative) || >>> (!TargetRange.NonNegative && SourceRange.NonNegative && >>> SourceRange.Width == TargetRange.Width)) { >>> >>> Modified: cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp?rev=259271&r1=259270&r2=259271&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp (original) >>> +++ cfe/trunk/test/CXX/expr/expr.const/p2-0x.cpp Fri Jan 29 17:51:16 2016 >>> @@ -242,8 +242,8 @@ namespace UndefinedBehavior { >>> constexpr int n13 = n5 + n5; // expected-error {{constant >>> expression}} expected-note {{value -4294967296 is outside the range of }} >>> constexpr int n14 = n3 - n5; // expected-error {{constant >>> expression}} expected-note {{value 4294967295 is outside the range of }} >>> constexpr int n15 = n5 * n5; // expected-error {{constant >>> expression}} expected-note {{value 4611686018427387904 is outside the range >>> of }} >>> - constexpr signed char c1 = 100 * 2; // ok >>> - constexpr signed char c2 = '\x64' * '\2'; // also ok >>> + constexpr signed char c1 = 100 * 2; // ok expected-warning{{changes >>> value}} >>> + constexpr signed char c2 = '\x64' * '\2'; // also ok >>> expected-warning{{changes value}} >>> constexpr long long ll1 = 0x7fffffffffffffff; // ok >>> constexpr long long ll2 = ll1 + 1; // expected-error {{constant}} >>> expected-note {{ 9223372036854775808 }} >>> constexpr long long ll3 = -ll1 - 1; // ok >>> >>> Modified: cfe/trunk/test/Sema/constant-conversion.c >>> URL: >>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/constant-conversion.c?rev=259271&r1=259270&r2=259271&view=diff >>> >>> ============================================================================== >>> --- cfe/trunk/test/Sema/constant-conversion.c (original) >>> +++ cfe/trunk/test/Sema/constant-conversion.c Fri Jan 29 17:51:16 2016 >>> @@ -80,3 +80,34 @@ void test8() { >>> struct { enum E x : 1; } f; >>> f.x = C; // expected-warning {{implicit truncation from 'int' to >>> bitfield changes value from 2 to 0}} >>> } >>> + >>> +void test9() { >>> + const char max_char = 0x7F; >>> + const short max_short = 0x7FFF; >>> + const int max_int = 0x7FFFFFFF; >>> + >>> + const short max_char_plus_one = (short)max_char + 1; >>> + const int max_short_plus_one = (int)max_short + 1; >>> + const long max_int_plus_one = (long)max_int + 1; >>> + >>> + char new_char = max_char_plus_one; // expected-warning {{implicit >>> conversion from 'const short' to 'char' changes value from 128 to -128}} >>> + short new_short = max_short_plus_one; // expected-warning {{implicit >>> conversion from 'const int' to 'short' changes value from 32768 to -32768}} >>> + int new_int = max_int_plus_one; // expected-warning {{implicit >>> conversion from 'const long' to 'int' changes value from 2147483648 to - >>> 2147483648}} >>> + >>> + char hex_char = 0x80; >>> + short hex_short = 0x8000; >>> + int hex_int = 0x80000000; >>> + >>> + char oct_char = 0200; >>> + short oct_short = 0100000; >>> + int oct_int = 020000000000; >>> + >>> + char bin_char = 0b10000000; >>> + short bin_short = 0b1000000000000000; >>> + int bin_int = 0b10000000000000000000000000000000; >>> + >>> +#define CHAR_MACRO_HEX 0xff >>> + char macro_char_hex = CHAR_MACRO_HEX; >>> +#define CHAR_MACRO_DEC 255 >>> + char macro_char_dec = CHAR_MACRO_DEC; // expected-warning {{implicit >>> conversion from 'int' to 'char' changes value from 255 to -1}} >>> +} >>> >>> >>> _______________________________________________ >>> cfe-commits mailing list >>> cfe-commits@lists.llvm.org >>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>> >> >> >
_______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
