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[C++] Define __STDC_CONSTANT_MACROS / __STDC_LIMIT_MACROS for stdint.h 

With some toolchains, building in C++ mode stumbles on many instances
of:

 In file included from ../../src/gdb/../include/splay-tree.h:43:0,
                  from ../../src/gdb/dcache.c:26:
 build-gnulib/import/inttypes.h:61:3: error: #error "This file assumes that 'int' has exactly 32 bits. Please report your platform and compiler to <bug-gnulib@gnu.org>."
  # error "This file assumes that 'int' has exactly 32 bits. Please report your platform and compiler to <bug-gnulib@gnu.org>."
    ^
 make: *** [dcache.o] Error 1

That's:

 #if !(INT_MIN == INT32_MIN && INT_MAX == INT32_MAX)
 # error "This file assumes that 'int' has exactly 32 bits. Please report your platform and compiler to <bug-gnulib@gnu.org>."
 #endif

I see it when cross building for --host=x86_64-w64-mingw32 using
Fedora 20's g++ (gcc version 4.8.4 20141219 (Fedora MinGW
4.8.4-1.fc20)), Simon reports seeing this on several cross compilers
too.

The issue is that on some hosts that predate C++11, when using C++ one
must define __STDC_CONSTANT_MACROS/__STDC_LIMIT_MACROS to make visible
the definitions of INTMAX_C / INTMAX_MAX etc.

This was a C99 requirement that later C++11 -- the first to define
stdint.h -- removed, and then C11 removed it as well.

https://www.gnu.org/software/gnulib/manual/html_node/stdint_002eh.html
says that gnulib's stdint.h fixes this, but because we run gnulib's
configure tests with a C compiler, gnulib determines that mingw's
stdint.h is C99-compliant, and doesn't actually replace it.  Actually,
even though configuring gnulib with a C++ compiler does result in
gnulib replacing stdint.h, the resulting replacement is broken for
mingw, because it defines uintptr_t incorrectly.  I sent a gnulib
patch upstream to fix that, here:

  https://lists.gnu.org/archive/html/bug-gnulib/2015-11/msg00004.html

but then even with that, gnulib still stumbles on other
configured-with-C++-compiler problems.

So for now, until gnulib + C++ is fixed upstream and then gdb's copy
is updated, which may take a while, I think it's best to keep
configuring gnulib in C, and define
__STDC_LIMIT_MACROS/__STDC_CONSTANT_MACROS ourselves, just like C99
intended.

gdb/ChangeLog:
2015-11-17  Pedro Alves  <palves@redhat.com>

	* common/common-defs.h (__STDC_CONSTANT_MACROS)
	(__STDC_LIMIT_MACROS): Define before including stdint.h.
This commit is contained in:
Pedro Alves 2015-11-17 15:17:45 +00:00
parent 95824559df
commit e063da6790
2 changed files with 21 additions and 0 deletions
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5
gdb/ChangeLog
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@ -1,3 +1,8 @@
2015-11-17 Pedro Alves <palves@redhat.com>
* common/common-defs.h (__STDC_CONSTANT_MACROS)
(__STDC_LIMIT_MACROS): Define before including stdint.h.
2015-11-17 Pedro Alves <palves@redhat.com>
* windows-nat.c (handle_exception): Return 0 for first chance

16
gdb/common/common-defs.h
View File

@ -31,7 +31,23 @@
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
/* From:
https://www.gnu.org/software/gnulib/manual/html_node/stdint_002eh.html
"On some hosts that predate C++11, when using C++ one must define
__STDC_CONSTANT_MACROS to make visible the definitions of constant
macros such as INTMAX_C, and one must define __STDC_LIMIT_MACROS to
make visible the definitions of limit macros such as INTMAX_MAX."
gnulib doesn't fix this for us correctly yet. See:
https://lists.gnu.org/archive/html/bug-gnulib/2015-11/msg00004.html
Meanwhile, explicitly define these ourselves, as C99 intended. */
#define __STDC_CONSTANT_MACROS 1
#define __STDC_LIMIT_MACROS 1
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <alloca.h>