[libcxx-dev] [clang] 4ede887 - PR45402: Make the restrictions on constant evaluation of memcmp and
David Zarzycki via cfe-commits
cfe-commits at lists.llvm.org
Sun Apr 5 15:41:09 PDT 2020
Subjectively speaking, using char8_t instead of char shouldn’t feel like a regression. So yes, making the builtin mem* functions work with char8_t again seems right. As for strlen, I can see arguments either way. Personally, if you’re concerned about clever macros, then I’d make the overload only visible in C++20 mode where char8_t was introduced.
--
Sent from my iPhone
> On Apr 5, 2020, at 18:18, Richard Smith <richard at metafoo.co.uk> wrote:
>
>
>> On Sun, 5 Apr 2020 at 14:44, David Zarzycki via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>
>> We have overloaded builtins. Can that not solve __builtin_strlen?
>
> I suppose it could, but we generally want __builtin_<libfunc> to behave the same as <libfunc>. (The difference would not be visible most of the time, but there's enough pre-existing use of __builtin_strlen through "clever" macros and the like that I'd be worried that this would break something important.) Maybe we should just make the mem* functions work again for char8_t; then you can use __builtin_memchr(p, 0) - p as an optimized compile-time strlen.
>
>> --
>> Sent from my iPhone
>>
>>>> On Apr 5, 2020, at 14:53, Richard Smith <richard at metafoo.co.uk> wrote:
>>>>
>>>
>>> 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
>>>> >
>>>> _______________________________________________
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