[binutils-gdb] Stop 'configure --enable-threading' if std::thread doesn't work

[binutils-gdb] Stop 'configure --enable-threading' if std::thread doesn't work

[Pedro Alves]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3e09762b7d1243d7d75c885537f67fa66416bb8b

commit 3e09762b7d1243d7d75c885537f67fa66416bb8b
Author: Pedro Alves <pedro@palves.net>
Date:   Tue May 14 15:43:41 2024 +0100

    Stop 'configure --enable-threading' if std::thread doesn't work
    
    Currently, if you configure gdb with explicit --enable-threading, but
    then configure detects std::thread does not work, configure silently
    disables threading support and continues configuring.
    
    This patch makes that scenario cause a configuration error, like so:
    
     $ /home/pedro/gdb/src/configure --enable-threading && make
     ...
     configure: error: std::thread does not work; disable threading
     make[1]: *** [Makefile:11225: configure-gdbsupport] Error 1
     make[1]: Leaving directory '/home/pedro/gdb/build-windows-threads'
     make: *** [Makefile:1041: all] Error 2
     $
    
    Additionally, if you don't explicitly pass --enable-threading, and
    std::thread does not work, we will now get a warning (and the build
    continues):
    
     $ /home/pedro/gdb/src/configure && make
     ...
     configure: WARNING: std::thread does not work; disabling threading
     ...
    
    This is similar to how we handle --enable-tui and missing curses.  The
    code and error/warning messages were borrowed from there.
    
    Change-Id: I73a8b580d1e2a796b23136920c0e181408ae1b22
    Approved-By: Tom Tromey <tom@tromey.com>

Diff:
---
 gdb/configure        | 14 +++++++++++---
 gdbserver/configure  | 14 +++++++++++---
 gdbsupport/common.m4 | 13 ++++++++++---
 gdbsupport/configure | 14 +++++++++++---
 4 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/gdb/configure b/gdb/configure
index 98cd488a737..66a7ad8d256 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -20181,12 +20181,13 @@ if test "${enable_threading+set}" = set; then :
     *) as_fn_error $? "bad value $enableval for threading" "$LINENO" 5 ;;
     esac
 else
-  want_threading=yes
+  want_threading=auto
 fi
 
 
   # Check for std::thread.  This does not work on some platforms, like
-  # mingw and DJGPP.
+  # mingw using the win32 threads model with gcc older than 13, and
+  # DJGPP.
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -20893,11 +20894,18 @@ done
   LIBS="$save_LIBS"
   CXXFLAGS="$save_CXXFLAGS"
 
-  if test "$want_threading" = "yes"; then
+  if test "$want_threading" != "no"; then
     if test "$gdb_cv_cxx_std_thread" = "yes"; then
 
 $as_echo "#define CXX_STD_THREAD 1" >>confdefs.h
 
+    else
+	if test "$want_threading" = "yes"; then
+	    as_fn_error $? "std::thread does not work; disable threading" "$LINENO" 5
+	else
+	    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: std::thread does not work; disabling threading" >&5
+$as_echo "$as_me: WARNING: std::thread does not work; disabling threading" >&2;}
+	fi
     fi
   fi
   ac_ext=c
diff --git a/gdbserver/configure b/gdbserver/configure
index 2da525ebf3b..3abc647acda 100755
--- a/gdbserver/configure
+++ b/gdbserver/configure
@@ -8888,12 +8888,13 @@ if test "${enable_threading+set}" = set; then :
     *) as_fn_error $? "bad value $enableval for threading" "$LINENO" 5 ;;
     esac
 else
-  want_threading=yes
+  want_threading=auto
 fi
 
 
   # Check for std::thread.  This does not work on some platforms, like
-  # mingw and DJGPP.
+  # mingw using the win32 threads model with gcc older than 13, and
+  # DJGPP.
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -9600,11 +9601,18 @@ done
   LIBS="$save_LIBS"
   CXXFLAGS="$save_CXXFLAGS"
 
-  if test "$want_threading" = "yes"; then
+  if test "$want_threading" != "no"; then
     if test "$gdb_cv_cxx_std_thread" = "yes"; then
 
 $as_echo "#define CXX_STD_THREAD 1" >>confdefs.h
 
+    else
+	if test "$want_threading" = "yes"; then
+	    as_fn_error $? "std::thread does not work; disable threading" "$LINENO" 5
+	else
+	    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: std::thread does not work; disabling threading" >&5
+$as_echo "$as_me: WARNING: std::thread does not work; disabling threading" >&2;}
+	fi
     fi
   fi
   ac_ext=c
diff --git a/gdbsupport/common.m4 b/gdbsupport/common.m4
index bef396445ba..6c317ff2450 100644
--- a/gdbsupport/common.m4
+++ b/gdbsupport/common.m4
@@ -89,10 +89,11 @@ AC_DEFUN([GDB_AC_COMMON], [
     no) want_threading=no ;;
     *) AC_MSG_ERROR([bad value $enableval for threading]) ;;
     esac],
-    [want_threading=yes])
+    [want_threading=auto])
 
   # Check for std::thread.  This does not work on some platforms, like
-  # mingw and DJGPP.
+  # mingw using the win32 threads model with gcc older than 13, and
+  # DJGPP.
   AC_LANG_PUSH([C++])
   AX_PTHREAD([threads=yes], [threads=no])
   save_LIBS="$LIBS"
@@ -128,10 +129,16 @@ AC_DEFUN([GDB_AC_COMMON], [
   LIBS="$save_LIBS"
   CXXFLAGS="$save_CXXFLAGS"
 
-  if test "$want_threading" = "yes"; then
+  if test "$want_threading" != "no"; then
     if test "$gdb_cv_cxx_std_thread" = "yes"; then
       AC_DEFINE(CXX_STD_THREAD, 1,
 		[Define to 1 if std::thread works.])
+    else
+	if test "$want_threading" = "yes"; then
+	    AC_MSG_ERROR([std::thread does not work; disable threading])
+	else
+	    AC_MSG_WARN([std::thread does not work; disabling threading])
+	fi
     fi
   fi
   AC_LANG_POP
diff --git a/gdbsupport/configure b/gdbsupport/configure
index a218b06ce28..19b19c42c6f 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -11662,12 +11662,13 @@ if test "${enable_threading+set}" = set; then :
     *) as_fn_error $? "bad value $enableval for threading" "$LINENO" 5 ;;
     esac
 else
-  want_threading=yes
+  want_threading=auto
 fi
 
 
   # Check for std::thread.  This does not work on some platforms, like
-  # mingw and DJGPP.
+  # mingw using the win32 threads model with gcc older than 13, and
+  # DJGPP.
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -12374,11 +12375,18 @@ done
   LIBS="$save_LIBS"
   CXXFLAGS="$save_CXXFLAGS"
 
-  if test "$want_threading" = "yes"; then
+  if test "$want_threading" != "no"; then
     if test "$gdb_cv_cxx_std_thread" = "yes"; then
 
 $as_echo "#define CXX_STD_THREAD 1" >>confdefs.h
 
+    else
+	if test "$want_threading" = "yes"; then
+	    as_fn_error $? "std::thread does not work; disable threading" "$LINENO" 5
+	else
+	    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: std::thread does not work; disabling threading" >&5
+$as_echo "$as_me: WARNING: std::thread does not work; disabling threading" >&2;}
+	fi
     fi
   fi
   ac_ext=c