d0b938a761
I started looking into this PR because in GCC 4.9 we were able to
detect the invalid
struct alignas(void) S{};
but I broke it in r210262.
It's ill-formed code in C++:
[dcl.align]/3: "An alignment-specifier of the form alignas(type-id) has
the same effect as alignas(alignof(type-id))", and [expr.align]/1:
"The operand shall be a type-id representing a complete object type,
or an array thereof, or a reference to one of those types." and void
is not a complete type.
It's also invalid in C:
6.7.5: _Alignas(type-name) is equivalent to _Alignas(_Alignof(type-name))
6.5.3.4: "The _Alignof operator shall not be applied to a function type
or an incomplete type."
We have a GNU extension whereby we treat sizeof(void) as 1, but I assume
it doesn't apply to alignof, at least in C++. However, __alignof__(void)
is still accepted with a -Wpedantic warning.
We still say "invalid application of 'alignof'" rather than 'alignas' in the
void diagnostic, but I felt that fixing that may not be suitable as part of
this patch. The "incomplete type" diagnostic still always prints
'__alignof__'.
PR c++/104944
gcc/cp/ChangeLog:
* typeck.cc (cxx_sizeof_or_alignof_type): Diagnose alignof(void).
(cxx_alignas_expr): Call cxx_sizeof_or_alignof_type with
complain == true.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/alignas20.C: New test.
|
||
|---|---|---|
| c++tools | ||
| config | ||
| contrib | ||
| fixincludes | ||
| gcc | ||
| gnattools | ||
| gotools | ||
| include | ||
| INSTALL | ||
| intl | ||
| libada | ||
| libatomic | ||
| libbacktrace | ||
| libcc1 | ||
| libcody | ||
| libcpp | ||
| libdecnumber | ||
| libffi | ||
| libgcc | ||
| libgfortran | ||
| libgo | ||
| libgomp | ||
| libiberty | ||
| libitm | ||
| libobjc | ||
| liboffloadmic | ||
| libphobos | ||
| libquadmath | ||
| libsanitizer | ||
| libssp | ||
| libstdc++-v3 | ||
| libvtv | ||
| lto-plugin | ||
| maintainer-scripts | ||
| zlib | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| ABOUT-NLS | ||
| ar-lib | ||
| ChangeLog | ||
| ChangeLog.jit | ||
| ChangeLog.tree-ssa | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING.LIB | ||
| COPYING.RUNTIME | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| depcomp | ||
| install-sh | ||
| libtool-ldflags | ||
| libtool.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| lt~obsolete.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| multilib.am | ||
| README | ||
| symlink-tree | ||
| test-driver | ||
| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.