[binutils-gdb] sim: Check known getopt definition existence

[binutils-gdb] sim: Check known getopt definition existence

[Andrew Burgess]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=340aa4f6872ca3c4f7fc4a79671537064d0ca91f

commit 340aa4f6872ca3c4f7fc4a79671537064d0ca91f
Author: Tsukasa OI <research_trasio@irq.a4lg.com>
Date:   Thu Oct 6 06:43:52 2022 +0000

    sim: Check known getopt definition existence
    
    Clang generates a warning if there is a function declaration/definition
    with zero arguments.  Such declarations/definitions without a prototype (an
    argument list) are deprecated forms of indefinite arguments
    ("-Wdeprecated-non-prototype").  On the default configuration, it causes a
    build failure (unless "--disable-werror" is specified).
    
    include/getopt.h defines some getopt function definitions but one of them
    has a form "extern int getopt ();".  If this form is selected in
    include/getopt.h, Clang generates a warning and the build fails by default.
    
    In really old environments, this getopt definition with no arguments is
    necessary (because the definition may change between environments).
    However, this definition is now a cause of problems on modern environments.
    
    A good news is, this definition is not always selected (e.g. if used by
    binutils/*.c).  This is because configuration scripts of binutils, gas,
    gprof and ld tries to find known definition of getopt function is used and
    defines HAVE_DECL_GETOPT macro.  If this macro is defined when getopt.h is
    included, a good form of getopt is used and Clang won't generate warnings.
    
    This commit adds a modified portion of ld/configure.ac to find the known
    getopt definition.  If we could find one (and we *will* in most modern
    environments), we don't need to rely on the deprecated definition.

Diff:
---
 sim/config.h.in  |  3 +++
 sim/configure    | 32 ++++++++++++++++++++++++++++++++
 sim/configure.ac | 10 ++++++++++
 3 files changed, 45 insertions(+)

diff --git a/sim/config.h.in b/sim/config.h.in
index 84c363c0aec..9a94b289e46 100644
--- a/sim/config.h.in
+++ b/sim/config.h.in
@@ -41,6 +41,9 @@
 /* Define to 1 if you have the `chmod' function. */
 #undef HAVE_CHMOD
 
+/* Is the prototype for getopt in <unistd.h> in the expected format? */
+#undef HAVE_DECL_GETOPT
+
 /* Define to 1 if you have the declaration of `tzname', and to 0 if you don't.
    */
 #undef HAVE_DECL_TZNAME
diff --git a/sim/configure b/sim/configure
index 75d1935df38..dac7f085be1 100755
--- a/sim/configure
+++ b/sim/configure
@@ -16428,6 +16428,38 @@ $as_echo "${WARN_CFLAGS} ${WERROR_CFLAGS}" >&6; }
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for a known getopt prototype in unistd.h" >&5
+$as_echo_n "checking for a known getopt prototype in unistd.h... " >&6; }
+if ${sim_cv_decl_getopt_unistd_h+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+extern int getopt (int, char *const*, const char *);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  sim_cv_decl_getopt_unistd_h=yes
+else
+  sim_cv_decl_getopt_unistd_h=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $sim_cv_decl_getopt_unistd_h" >&5
+$as_echo "$sim_cv_decl_getopt_unistd_h" >&6; }
+if test $sim_cv_decl_getopt_unistd_h = yes; then
+
+$as_echo "#define HAVE_DECL_GETOPT 1" >>confdefs.h
+
+fi
+
 
 
 
diff --git a/sim/configure.ac b/sim/configure.ac
index 66a1020efe0..be0cfdbea32 100644
--- a/sim/configure.ac
+++ b/sim/configure.ac
@@ -177,6 +177,16 @@ SIM_AC_OPTION_STDIO
 SIM_AC_OPTION_TRACE
 SIM_AC_OPTION_WARNINGS
 
+AC_MSG_CHECKING(for a known getopt prototype in unistd.h)
+AC_CACHE_VAL(sim_cv_decl_getopt_unistd_h,
+[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <unistd.h>], [extern int getopt (int, char *const*, const char *);])],
+sim_cv_decl_getopt_unistd_h=yes, sim_cv_decl_getopt_unistd_h=no)])
+AC_MSG_RESULT($sim_cv_decl_getopt_unistd_h)
+if test $sim_cv_decl_getopt_unistd_h = yes; then
+  AC_DEFINE([HAVE_DECL_GETOPT], 1,
+	    [Is the prototype for getopt in <unistd.h> in the expected format?])
+fi
+
 dnl These are unfortunate.  They are conditionally called by other sim macros
 dnl but always used by common/Make-common.in.  So we have to subst here even
 dnl when the rest of the code is in the respective macros.  Once we merge the