From c560a5fbae3b6e0b7c2119e6fc276941517377fa Mon Sep 17 00:00:00 2001
From: Tom Tromey <tromey@adacore.com>
Date: Thu, 31 Mar 2022 08:26:12 -0600
Subject: Let std::thread check pass even without pthreads

Currently, the configure check for std::thread relies on pthreads
existing.  However, this means that if std::thread is implemented for
a non-pthreads host, then the check will yield the wrong answer.  This
happened in AdaCore internal builds.  Here, we have this GCC patch:

    https://gcc.gnu.org/legacy-ml/gcc-patches/2019-06/msg01840.html

... which adds mingw support to GCC's gthreads implementation, and
also to std::thread.

This configure change fixes this problem and enables threading for
gdb.
---
 gdb/configure | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

(limited to 'gdb/configure')

diff --git a/gdb/configure b/gdb/configure
index 7ae8a2a..7225c7f 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -14668,12 +14668,11 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
 ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
 
 
-  if test "$threads" = "yes"; then
-    save_LIBS="$LIBS"
-    LIBS="$PTHREAD_LIBS $LIBS"
-    save_CXXFLAGS="$CXXFLAGS"
-    CXXFLAGS="$PTHREAD_CFLAGS $save_CXXFLAGS"
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for std::thread" >&5
+  save_LIBS="$LIBS"
+  LIBS="$PTHREAD_LIBS $LIBS"
+  save_CXXFLAGS="$CXXFLAGS"
+  CXXFLAGS="$PTHREAD_CFLAGS $save_CXXFLAGS"
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for std::thread" >&5
 $as_echo_n "checking for std::thread... " >&6; }
 if ${gdb_cv_cxx_std_thread+:} false; then :
   $as_echo_n "(cached) " >&6
@@ -14681,7 +14680,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <thread>
-      void callback() { }
+    void callback() { }
 int
 main ()
 {
@@ -14700,6 +14699,7 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gdb_cv_cxx_std_thread" >&5
 $as_echo "$gdb_cv_cxx_std_thread" >&6; }
 
+  if test "$threads" = "yes"; then
     # This check must be here, while LIBS includes any necessary
     # threading library.
     for ac_func in pthread_sigmask pthread_setname_np
@@ -14714,10 +14714,9 @@ _ACEOF
 fi
 done
 
-
-    LIBS="$save_LIBS"
-    CXXFLAGS="$save_CXXFLAGS"
   fi
+  LIBS="$save_LIBS"
+  CXXFLAGS="$save_CXXFLAGS"
 
   if test "$want_threading" = "yes"; then
     if test "$gdb_cv_cxx_std_thread" = "yes"; then
-- 
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