[libcxx-dev] [clang] 4ede887 - PR45402: Make the restrictions on constant evaluation of memcmp and
Richard Smith via libcxx-dev
libcxx-dev at lists.llvm.org
Sun Apr 5 11:52:56 PDT 2020
Thanks. We need to figure out what the right way to support char8_t with
string builtins is. These ones could work in principle, whereas things like
__builtin_strlen would never work because they take operands of the wrong
types (and we can't cast const char8_t* -> const char* in a constant
expression).
On Sun, 5 Apr 2020 at 04:14, David Zarzycki via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
> Hi Richard,
>
> I'm going to commit a narrow fix to clang to make the libcxx test suite
> pass again by allowing char8_t again. If you feel that this is the wrong
> long-term solution, please help the libcxx folks with whatever adjustments
> they need.
>
> Thanks!
>
> Dave
>
>
> On Sat, Apr 4, 2020, at 9:55 AM, David Zarzycki via libcxx-dev wrote:
> > Hi Richard,
> >
> > This breaks libcxx. Can we please revert this or is a quick fix to
> > libcxx possible?
> >
> >
> > FAIL: libc++ ::
> >
> std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
> (58624 of 62672)
> > ******************** TEST 'libc++ ::
> >
> std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp'
> FAILED ********************
> > Command: ['/p/tllvm/bin/clang++', '-o',
> >
> '/tmp/_update_lc/t/projects/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/Output/compare.pass.cpp.o',
> '-x', 'c++',
> '/home/dave/s/lp/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp',
> '-c', '-v', '-Werror=thread-safety', '-std=c++2a', '-include',
> '/home/dave/s/lp/libcxx/test/support/nasty_macros.h', '-nostdinc++',
> '-I/home/dave/s/lp/libcxx/include',
> '-I/tmp/_update_lc/t/projects/libcxx/include/c++build',
> '-D__STDC_FORMAT_MACROS', '-D__STDC_LIMIT_MACROS',
> '-D__STDC_CONSTANT_MACROS', '-I/home/dave/s/lp/libcxx/test/support',
> '-ftemplate-depth=270', '-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER', '-Wall',
> '-Wextra', '-Werror', '-Wuser-defined-warnings', '-Wshadow',
> '-Wno-unused-command-line-argument', '-Wno-attributes',
> '-Wno-pessimizing-move', '-Wno-c++11-extensions',
> '-Wno-user-defined-literals', '-Wno-noexcept-type', '-Wsign-compare',
> '-Wunused-variable', '-Wunused-parameter', '-Wunreachable-code', '-c']
> > Exit Code: 1
> > Standard Error:
> > --
> > clang version 11.0.0 (https://github.com/llvm/llvm-project.git
> > 22127da8f17c03c69231f3631472f7f99ad9cb7f)
> > Target: x86_64-unknown-linux-gnu
> > Thread model: posix
> > InstalledDir: /p/tllvm/bin
> > Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/9
> > Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/9
> > Candidate multilib: .;@m64
> > Candidate multilib: 32;@m32
> > Selected multilib: .;@m64
> > (in-process)
> > "/p/tllvm/bin/clang-11" -cc1 -triple x86_64-unknown-linux-gnu
> > -emit-obj -mrelax-all -disable-free -disable-llvm-verifier
> > -discard-value-names -main-file-name compare.pass.cpp
> > -mrelocation-model static -mthread-model posix -mframe-pointer=all
> > -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables
> > -target-cpu x86-64 -dwarf-column-info -fno-split-dwarf-inlining
> > -debugger-tuning=gdb -v -nostdinc++ -resource-dir
> > /p/tllvm/lib64/clang/11.0.0 -include
> > /home/dave/s/lp/libcxx/test/support/nasty_macros.h -I
> > /home/dave/s/lp/libcxx/include -I
> > /tmp/_update_lc/t/projects/libcxx/include/c++build -D
> > __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS
> > -I /home/dave/s/lp/libcxx/test/support -D
> > _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER -internal-isystem
> > /usr/local/include -internal-isystem
> > /p/tllvm/lib64/clang/11.0.0/include -internal-externc-isystem /include
> > -internal-externc-isystem /usr/include -Werror=thread-safety -Wall
> > -Wextra -Werror -Wuser-defined-warnings -Wshadow
> > -Wno-unused-command-line-argument -Wno-attributes -Wno-pessimizing-move
> > -Wno-c++11-extensions -Wno-user-defined-literals -Wno-noexcept-type
> > -Wsign-compare -Wunused-variable -Wunused-parameter -Wunreachable-code
> > -std=c++2a -fdeprecated-macro -fdebug-compilation-dir
> >
> /tmp/_update_lc/t/projects/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t
> -ftemplate-depth 270 -ferror-limit 19 -fgnuc-version=4.2.1
> -fno-implicit-modules -fcxx-exceptions -fexceptions -faddrsig -o
> /tmp/_update_lc/t/projects/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/Output/compare.pass.cpp.o
> -x c++
> /home/dave/s/lp/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
> > clang -cc1 version 11.0.0 based upon LLVM 11.0.0git default target
> > x86_64-unknown-linux-gnu
> > ignoring nonexistent directory "/include"
> > #include "..." search starts here:
> > #include <...> search starts here:
> > /home/dave/s/lp/libcxx/include
> > /tmp/_update_lc/t/projects/libcxx/include/c++build
> > /home/dave/s/lp/libcxx/test/support
> > /usr/local/include
> > /p/tllvm/lib64/clang/11.0.0/include
> > /usr/include
> > End of search list.
> >
> /home/dave/s/lp/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp:53:19:
> error: static_assert expression is not an integral constant expression
> > static_assert(test_constexpr(), "" );
> > ^~~~~~~~~~~~~~~~
> > /home/dave/s/lp/libcxx/include/__string:662:12: note: constant
> > evaluation of '__builtin_memcmp' between arrays of types 'const
> > char8_t' and 'const char8_t' is not supported; only arrays of narrow
> > character types can be compared
> > return __builtin_memcmp(__s1, __s2, __n);
> > ^
> >
> /home/dave/s/lp/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp:24:12:
> note: in call to 'compare(&u8"123"[0], &u8"223"[0], 3)'
> > return std::char_traits<char8_t>::compare(u8"123", u8"223", 3) < 0
> > ^
> >
> /home/dave/s/lp/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp:53:19:
> note: in call to 'test_constexpr()'
> > static_assert(test_constexpr(), "" );
> > ^
> > 1 error generated.
> > --
> >
> > Compilation failed unexpectedly!
> > ********************
> >
> > Testing Time: 135.49s
> > ********************
> > Failing Tests (1):
> > libc++ ::
> >
> std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
> >
> > Expected Passes : 45503
> > Expected Failures : 118
> > Unsupported Tests : 17050
> > Unexpected Failures: 1
> >
> >
> > On Fri, Apr 3, 2020, at 9:26 PM, Richard Smith via cfe-commits wrote:
> > >
> > > Author: Richard Smith
> > > Date: 2020-04-03T18:26:14-07:00
> > > New Revision: 4ede8879924c08ae5b495d3f421c167d822a60be
> > >
> > > URL:
> > >
> https://github.com/llvm/llvm-project/commit/4ede8879924c08ae5b495d3f421c167d822a60be
> > > DIFF:
> > >
> https://github.com/llvm/llvm-project/commit/4ede8879924c08ae5b495d3f421c167d822a60be.diff
> > >
> > > LOG: PR45402: Make the restrictions on constant evaluation of memcmp
> and
> > > memchr consistent and comprehensible, and document them.
> > >
> > > We previously allowed evaluation of memcmp on arrays of integers of any
> > > size, so long as the call evaluated to 0, and allowed evaluation of
> > > memchr on any array of integral type of size 1 (including enums). The
> > > purpose of constant-evaluating these builtins is only to support
> > > constexpr std::char_traits, so we now consistently allow them on arrays
> > > of (possibly signed or unsigned) char only.
> > >
> > > Added:
> > >
> > >
> > > Modified:
> > > clang/docs/LanguageExtensions.rst
> > > clang/include/clang/Basic/DiagnosticASTKinds.td
> > > clang/lib/AST/ExprConstant.cpp
> > > clang/test/SemaCXX/constexpr-string.cpp
> > >
> > > Removed:
> > >
> > >
> > >
> > >
> ################################################################################
> > > diff --git a/clang/docs/LanguageExtensions.rst
> > > b/clang/docs/LanguageExtensions.rst
> > > index 558ce7dee653..6dcfd1a49f06 100644
> > > --- a/clang/docs/LanguageExtensions.rst
> > > +++ b/clang/docs/LanguageExtensions.rst
> > > @@ -2333,10 +2333,11 @@ String builtins
> > > ---------------
> > >
> > > Clang provides constant expression evaluation support for builtins
> forms of
> > > -the following functions from the C standard library ``<string.h>``
> header:
> > > +the following functions from the C standard library headers
> > > +``<string.h>`` and ``<wchar.h>``:
> > >
> > > * ``memchr``
> > > -* ``memcmp``
> > > +* ``memcmp`` (and its deprecated BSD / POSIX alias ``bcmp``)
> > > * ``strchr``
> > > * ``strcmp``
> > > * ``strlen``
> > > @@ -2366,7 +2367,11 @@ In addition to the above, one further builtin
> is
> > > provided:
> > > constant expressions in C++11 onwards (where a cast from ``void*`` to
> > > ``char*``
> > > is disallowed in general).
> > >
> > > -Support for constant expression evaluation for the above builtins be
> > > detected
> > > +Constant evaluation support for the ``__builtin_mem*`` functions is
> > > provided
> > > +only for arrays of ``char``, ``signed char``, or ``unsigned char``,
> > > despite
> > > +these functions accepting an argument of type ``const void*``.
> > > +
> > > +Support for constant expression evaluation for the above builtins can
> > > be detected
> > > with ``__has_feature(cxx_constexpr_string_builtins)``.
> > >
> > > Memory builtins
> > > @@ -2386,6 +2391,25 @@ more information.
> > >
> > > Note that the `size` argument must be a compile time constant.
> > >
> > > +Clang provides constant expression evaluation support for builtin
> > > forms of the
> > > +following functions from the C standard library headers
> > > +``<string.h>`` and ``<wchar.h>``:
> > > +
> > > +* ``memcpy``
> > > +* ``memmove``
> > > +* ``wmemcpy``
> > > +* ``wmemmove``
> > > +
> > > +In each case, the builtin form has the name of the C library function
> > > prefixed
> > > +by ``__builtin_``.
> > > +
> > > +Constant evaluation support is only provided when the source and
> > > destination
> > > +are pointers to arrays with the same trivially copyable element type,
> > > and the
> > > +given size is an exact multiple of the element size that is no
> greater
> > > than
> > > +the number of elements accessible through the source and destination
> > > operands.
> > > +
> > > +Constant evaluation support is not yet provided for
> > > ``__builtin_memcpy_inline``.
> > > +
> > > Atomic Min/Max builtins with memory ordering
> > > --------------------------------------------
> > >
> > >
> > > diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td
> > > b/clang/include/clang/Basic/DiagnosticASTKinds.td
> > > index 544573edffdf..a1415f9ec0e1 100644
> > > --- a/clang/include/clang/Basic/DiagnosticASTKinds.td
> > > +++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
> > > @@ -244,6 +244,12 @@ def note_constexpr_unsupported_unsized_array :
> > > Note<
> > > def note_constexpr_unsized_array_indexed : Note<
> > > "indexing of array without known bound is not allowed "
> > > "in a constant expression">;
> > > +def note_constexpr_memcmp_unsupported : Note<
> > > + "constant evaluation of %0 between arrays of types %1 and %2 "
> > > + "is not supported; only arrays of narrow character types can be
> > > compared">;
> > > +def note_constexpr_memchr_unsupported : Note<
> > > + "constant evaluation of %0 on array of type %1 "
> > > + "is not supported; only arrays of narrow character types can be
> > > searched">;
> > > def note_constexpr_memcpy_null : Note<
> > > "%select{source|destination}2 of "
> > > "'%select{%select{memcpy|wmemcpy}1|%select{memmove|wmemmove}1}0' "
> > >
> > > diff --git a/clang/lib/AST/ExprConstant.cpp
> > > b/clang/lib/AST/ExprConstant.cpp
> > > index c6e1cc7b67df..a83b2e24e17f 100644
> > > --- a/clang/lib/AST/ExprConstant.cpp
> > > +++ b/clang/lib/AST/ExprConstant.cpp
> > > @@ -8469,8 +8469,12 @@ bool
> > > PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
> > > }
> > > // Give up on byte-oriented matching against multibyte elements.
> > > // FIXME: We can compare the bytes in the correct order.
> > > - if (IsRawByte && Info.Ctx.getTypeSizeInChars(CharTy) !=
> > > CharUnits::One())
> > > + if (IsRawByte && !CharTy->isCharType()) {
> > > + Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
> > > + << (std::string("'") +
> > > Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
> > > + << CharTy;
> > > return false;
> > > + }
> > > // Figure out what value we're actually looking for (after
> > > converting to
> > > // the corresponding unsigned type if necessary).
> > > uint64_t DesiredVal;
> > > @@ -8586,6 +8590,7 @@ bool
> > > PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
> > > QualType T = Dest.Designator.getType(Info.Ctx);
> > > QualType SrcT = Src.Designator.getType(Info.Ctx);
> > > if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
> > > + // FIXME: Consider using our bit_cast implementation to support
> > > this.
> > > Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move <<
> > > SrcT << T;
> > > return false;
> > > }
> > > @@ -11149,6 +11154,16 @@ bool
> > > IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
> > > CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
> > > Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
> > >
> > > + // For memcmp, allow comparing any arrays of '[[un]signed] char',
> > > + // but no other types.
> > > + if (IsRawByte && !(CharTy1->isCharType() &&
> > > CharTy2->isCharType())) {
> > > + // FIXME: Consider using our bit_cast implementation to support
> > > this.
> > > + Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
> > > + << (std::string("'") +
> > > Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
> > > + << CharTy1 << CharTy2;
> > > + return false;
> > > + }
> > > +
> > > const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
> > > return handleLValueToRValueConversion(Info, E, CharTy1,
> String1,
> > > Char1) &&
> > > handleLValueToRValueConversion(Info, E, CharTy2,
> String2,
> > > Char2) &&
> > > @@ -11159,57 +11174,6 @@ bool
> > > IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
> > > HandleLValueArrayAdjustment(Info, E, String2, CharTy2,
> 1);
> > > };
> > >
> > > - if (IsRawByte) {
> > > - uint64_t BytesRemaining = MaxLength;
> > > - // Pointers to const void may point to objects of incomplete
> > > type.
> > > - if (CharTy1->isIncompleteType()) {
> > > - Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) <<
> > > CharTy1;
> > > - return false;
> > > - }
> > > - if (CharTy2->isIncompleteType()) {
> > > - Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) <<
> > > CharTy2;
> > > - return false;
> > > - }
> > > - uint64_t CharTy1Width{Info.Ctx.getTypeSize(CharTy1)};
> > > - CharUnits CharTy1Size =
> > > Info.Ctx.toCharUnitsFromBits(CharTy1Width);
> > > - // Give up on comparing between elements with disparate widths.
> > > - if (CharTy1Size != Info.Ctx.getTypeSizeInChars(CharTy2))
> > > - return false;
> > > - uint64_t BytesPerElement = CharTy1Size.getQuantity();
> > > - assert(BytesRemaining && "BytesRemaining should not be zero:
> the
> > > "
> > > - "following loop considers at least one
> > > element");
> > > - while (true) {
> > > - APValue Char1, Char2;
> > > - if (!ReadCurElems(Char1, Char2))
> > > - return false;
> > > - // We have compatible in-memory widths, but a possible type
> and
> > > - // (for `bool`) internal representation mismatch.
> > > - // Assuming two's complement representation, including 0 for
> > > `false` and
> > > - // 1 for `true`, we can check an appropriate number of
> > > elements for
> > > - // equality even if they are not byte-sized.
> > > - APSInt Char1InMem = Char1.getInt().extOrTrunc(CharTy1Width);
> > > - APSInt Char2InMem = Char2.getInt().extOrTrunc(CharTy1Width);
> > > - if (Char1InMem.ne(Char2InMem)) {
> > > - // If the elements are byte-sized, then we can produce a
> > > three-way
> > > - // comparison result in a straightforward manner.
> > > - if (BytesPerElement == 1u) {
> > > - // memcmp always compares unsigned chars.
> > > - return Success(Char1InMem.ult(Char2InMem) ? -1 : 1, E);
> > > - }
> > > - // The result is byte-order sensitive, and we have
> multibyte
> > > elements.
> > > - // FIXME: We can compare the remaining bytes in the correct
> > > order.
> > > - return false;
> > > - }
> > > - if (!AdvanceElems())
> > > - return false;
> > > - if (BytesRemaining <= BytesPerElement)
> > > - break;
> > > - BytesRemaining -= BytesPerElement;
> > > - }
> > > - // Enough elements are equal to account for the memcmp limit.
> > > - return Success(0, E);
> > > - }
> > > -
> > > bool StopAtNull =
> > > (BuiltinOp != Builtin::BImemcmp && BuiltinOp !=
> > > Builtin::BIbcmp &&
> > > BuiltinOp != Builtin::BIwmemcmp &&
> > > @@ -11227,7 +11191,7 @@ bool
> > > IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
> > > APValue Char1, Char2;
> > > if (!ReadCurElems(Char1, Char2))
> > > return false;
> > > - if (Char1.getInt() != Char2.getInt()) {
> > > + if (Char1.getInt().ne(Char2.getInt())) {
> > > if (IsWide) // wmemcmp compares with wchar_t signedness.
> > > return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
> > > // memcmp always compares unsigned chars.
> > >
> > > diff --git a/clang/test/SemaCXX/constexpr-string.cpp
> > > b/clang/test/SemaCXX/constexpr-string.cpp
> > > index f540be8f8e5b..79ac3bf2cc4d 100644
> > > --- a/clang/test/SemaCXX/constexpr-string.cpp
> > > +++ b/clang/test/SemaCXX/constexpr-string.cpp
> > > @@ -47,7 +47,7 @@ extern "C" {
> > > extern wchar_t *wmemmove(wchar_t *d, const wchar_t *s, size_t n);
> > > }
> > >
> > > -# 45 "SemaCXX/constexpr-string.cpp" 2
> > > +# 51 "SemaCXX/constexpr-string.cpp" 2
> > > namespace Strlen {
> > > constexpr int n = __builtin_strlen("hello"); // ok
> > > static_assert(n == 5);
> > > @@ -121,13 +121,13 @@ namespace StrcmpEtc {
> > > extern struct Incomplete incomplete;
> > > static_assert(__builtin_memcmp(&incomplete, "", 0u) == 0);
> > > static_assert(__builtin_memcmp("", &incomplete, 0u) == 0);
> > > - static_assert(__builtin_memcmp(&incomplete, "", 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{read of
> > > incomplete type 'struct Incomplete'}}
> > > - static_assert(__builtin_memcmp("", &incomplete, 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{read of
> > > incomplete type 'struct Incomplete'}}
> > > + static_assert(__builtin_memcmp(&incomplete, "", 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{not
> > > supported}}
> > > + static_assert(__builtin_memcmp("", &incomplete, 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{not
> > > supported}}
> > >
> > > static_assert(__builtin_bcmp(&incomplete, "", 0u) == 0);
> > > static_assert(__builtin_bcmp("", &incomplete, 0u) == 0);
> > > - static_assert(__builtin_bcmp(&incomplete, "", 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{read of
> > > incomplete type 'struct Incomplete'}}
> > > - static_assert(__builtin_bcmp("", &incomplete, 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{read of
> > > incomplete type 'struct Incomplete'}}
> > > + static_assert(__builtin_bcmp(&incomplete, "", 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{not
> > > supported}}
> > > + static_assert(__builtin_bcmp("", &incomplete, 1u) == 42); //
> > > expected-error {{not an integral constant}} expected-note {{not
> > > supported}}
> > >
> > > constexpr unsigned char ku00fe00[] = {0x00, 0xfe, 0x00};
> > > constexpr unsigned char ku00feff[] = {0x00, 0xfe, 0xff};
> > > @@ -155,11 +155,11 @@ namespace StrcmpEtc {
> > >
> > > struct Bool3Tuple { bool bb[3]; };
> > > constexpr Bool3Tuple kb000100 = {{false, true, false}};
> > > - static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00,
> > > kb000100.bb, 1) == 0);
> > > - static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00,
> > > kb000100.bb, 2) == 1);
> > > + static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00,
> > > kb000100.bb, 1) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(sizeof(bool) != 1u || __builtin_memcmp(ks00fe00,
> > > kb000100.bb, 2) == 1); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > >
> > > - static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00,
> > > kb000100.bb, 1) == 0);
> > > - static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00,
> > > kb000100.bb, 2) != 0);
> > > + static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00,
> > > kb000100.bb, 1) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(sizeof(bool) != 1u || __builtin_bcmp(ks00fe00,
> > > kb000100.bb, 2) != 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > >
> > > constexpr long ksl[] = {0, -1};
> > > constexpr unsigned int kui[] = {0, 0u - 1};
> > > @@ -173,25 +173,25 @@ namespace StrcmpEtc {
> > > return nullptr;
> > > }
> > > }
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) -
> > > 1) == 0);
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) +
> > > 0) == 0);
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) +
> > > 1) == 0);
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> -
> > > 1) == 0);
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> +
> > > 0) == 0);
> > > - static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> +
> > > 1) == 42); // expected-error {{not an integral constant}}
> expected-note
> > > {{dereferenced one-past-the-end}}
> > > - static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) - 1) == 0);
> > > - static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 0) == 0);
> > > - static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 1) == 42); // expected-error {{not an integral
> > > constant}} expected-note {{dereferenced one-past-the-end}}
> > > -
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) - 1)
> > > == 0);
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 0)
> > > == 0);
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 1)
> > > == 0);
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) -
> > > 1) == 0);
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) +
> > > 0) == 0);
> > > - static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) +
> > > 1) == 42); // expected-error {{not an integral constant}}
> expected-note
> > > {{dereferenced one-past-the-end}}
> > > - static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) - 1) == 0);
> > > - static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 0) == 0);
> > > - static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 1) == 42); // expected-error {{not an integral
> > > constant}} expected-note {{dereferenced one-past-the-end}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) -
> > > 1) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) +
> > > 0) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), sizeof(long) +
> > > 1) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> -
> > > 1) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> +
> > > 0) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_memcmp(ksl, kuSizeofLong(), 2*sizeof(long)
> +
> > > 1) == 42); // expected-error {{constant}} expected-note {{not
> > > supported}}
> > > + static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) - 1) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 0) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(__builtin_memcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 1) == 42); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > +
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) - 1)
> > > == 0); // expected-error {{constant}} expected-note {{not supported}}
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 0)
> > > == 0); // expected-error {{constant}} expected-note {{not supported}}
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), sizeof(long) + 1)
> > > == 0); // expected-error {{constant}} expected-note {{not supported}}
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) -
> > > 1) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) +
> > > 0) == 0); // expected-error {{constant}} expected-note {{not
> supported}}
> > > + static_assert(__builtin_bcmp(ksl, kuSizeofLong(), 2*sizeof(long) +
> > > 1) == 42); // expected-error {{constant}} expected-note {{not
> > > supported}}
> > > + static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) - 1) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 0) == 0); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > > + static_assert(__builtin_bcmp(ksl + 1, kuSizeofLong() + 1,
> > > sizeof(long) + 1) == 42); // expected-error {{constant}} expected-note
> > > {{not supported}}
> > >
> > > constexpr int a = strcmp("hello", "world"); // expected-error
> > > {{constant expression}} expected-note {{non-constexpr function
> 'strcmp'
> > > cannot be used in a constant expression}}
> > > constexpr int b = strncmp("hello", "world", 3); // expected-error
> > > {{constant expression}} expected-note {{non-constexpr function
> > > 'strncmp' cannot be used in a constant expression}}
> > > @@ -385,14 +385,14 @@ namespace StrchrEtc {
> > > enum class E : unsigned char {};
> > > struct EPair { E e, f; };
> > > constexpr EPair ee{E{240}};
> > > - static_assert(__builtin_memchr(&ee.e, 240, 1) == &ee.e);
> > > + static_assert(__builtin_memchr(&ee.e, 240, 1) == &ee.e); //
> > > expected-error {{constant}} expected-note {{not supported}}
> > >
> > > constexpr bool kBool[] = {false, true, false};
> > > constexpr const bool *const kBoolPastTheEndPtr = kBool + 3;
> > > - static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr - 3, 1, 99) == kBool + 1);
> > > - static_assert(sizeof(bool) != 1u || __builtin_memchr(kBool + 1, 0,
> > > 99) == kBoolPastTheEndPtr - 1);
> > > - static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr - 3, -1, 3) == nullptr);
> > > - static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr, 0, 1) == nullptr); //
> > > expected-error {{not an integral constant}} expected-note
> > > {{dereferenced one-past-the-end}}
> > > + static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr - 3, 1, 99) == kBool + 1); //
> > > expected-error {{constant}} expected-note {{not supported}}
> > > + static_assert(sizeof(bool) != 1u || __builtin_memchr(kBool + 1, 0,
> > > 99) == kBoolPastTheEndPtr - 1); // expected-error {{constant}}
> > > expected-note {{not supported}}
> > > + static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr - 3, -1, 3) == nullptr); //
> > > expected-error {{constant}} expected-note {{not supported}}
> > > + static_assert(sizeof(bool) != 1u ||
> > > __builtin_memchr(kBoolPastTheEndPtr, 0, 1) == nullptr); //
> > > expected-error {{constant}} expected-note {{not supported}}
> > >
> > > static_assert(__builtin_char_memchr(kStr, 'a', 0) == nullptr);
> > > static_assert(__builtin_char_memchr(kStr, 'a', 1) == kStr);
> > >
> > >
> > >
> > > _______________________________________________
> > > cfe-commits mailing list
> > > cfe-commits at lists.llvm.org
> > > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
> > >
> > _______________________________________________
> > libcxx-dev mailing list
> > libcxx-dev at lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/libcxx-dev
> >
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>
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