[Bug binutils/28341] New: gdb_proc_service.h use of non-standard typeof

[liulk at likai dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28341

            Bug ID: 28341
           Summary: gdb_proc_service.h use of non-standard typeof
           Product: binutils
           Version: 2.38 (HEAD)
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: liulk at likai dot org
  Target Milestone: ---

This commit introduced a macro PS_EXPORT that uses a non-standard typeof.

https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=790f17188a22e722bab9915e1d50307f8cb7c0f9

This causes problems when CXX is set to "g++ -std=c++11", which does not
recognize the non-standard typeof.  It must use the alternate keyword
__typeof__.

https://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate-Keywords

I encountered the scenario where CXX is set to "g++ -std=c++11" when I try to
compile binutils under GCC as part of the GCC 3-stage compilation, which is
common for building a cross-compiler.

https://gcc.gnu.org/install/build.html

When using non-standard typeof with "g++ -std=c++11", it causes compilation
errors like these:

make[2]: Entering directory '/tmp/build/binutils/gdbserver'
g++ -std=c++11     -I. -I/sources/gcc/binutils/gdbserver
-I/sources/gcc/binutils
/gdbserver/../gdb/regformats -I/sources/gcc/binutils/gdbserver/..
-I/sources/gcc
/binutils/gdbserver/../include -I/sources/gcc/binutils/gdbserver/../gdb
-I/sourc
es/gcc/binutils/gdbserver/../gnulib/import -I../gnulib/import
-I/sources/gcc/bin
utils/gdbserver/.. -I..   -pthread -Wall -Wpointer-arith -Wno-unused
-Wunused-va
lue -Wunused-variable -Wunused-function -Wno-switch -Wno-char-subscripts
-Wempty
-body -Wunused-but-set-parameter -Wunused-but-set-variable -Wno-sign-compare
-Wn
o-error=maybe-uninitialized -Wno-mismatched-tags -Wsuggest-override
-Wimplicit-f
allthrough=3 -Wduplicated-cond -Wshadow=local -Wdeprecated-copy
-Wdeprecated-cop
y-dtor -Wredundant-move -Wmissing-declarations -Wstrict-null-sentinel -Wformat
-
Wformat-nonliteral  -DGDBSERVER -g     -c -o linux-x86-low.o -MT
linux-x86-low.o
 -MMD -MP -MF ./.deps/linux-x86-low.Tpo
/sources/gcc/binutils/gdbserver/linux-x8
6-low.cc
In file included from /sources/gcc/binutils/gdbserver/gdb_proc_service.h:22,
                 from /sources/gcc/binutils/gdbserver/linux-low.h:27,
                 from /sources/gcc/binutils/gdbserver/linux-x86-low.cc:24:
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:177:50: error: 
expected constructor, destructor, or type conversion before '(' token
  177 |   __attribute__((visibility ("default"))) typeof (SYM) SYM
      |                                                  ^
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:179:1: note:
in
 expansion of macro 'PS_EXPORT'
  179 | PS_EXPORT (ps_get_thread_area);
      | ^~~~~~~~~
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:177:50: error: 
expected constructor, destructor, or type conversion before '(' token
  177 |   __attribute__((visibility ("default"))) typeof (SYM) SYM
      |                                                  ^
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:180:1: note:
in
 expansion of macro 'PS_EXPORT'
  180 | PS_EXPORT (ps_getpid);
      | ^~~~~~~~~
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:177:50: error: 
expected constructor, destructor, or type conversion before '(' token
  177 |   __attribute__((visibility ("default"))) typeof (SYM) SYM
      |                                                  ^
/sources/gcc/binutils/gdbserver/../gdbsupport/gdb_proc_service.h:181:1: note:
in
 expansion of macro 'PS_EXPORT'
  181 | PS_EXPORT (ps_lcontinue);
      | ^~~~~~~~~

The fix is simply to change the definition of PS_EXPORT to use __typeof__ like
this:

#define PS_EXPORT(SYM)                                          \
  __attribute__((visibility ("default"))) __typeof__ (SYM) SYM

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