libstdc++: Allow 'configure.host' to pre-set 'EXTRA_CFLAGS', 'EXTRA_CXX_FLAGS'

In particular, 'GLIBCXX_ENABLE_CXX_FLAGS' shouldn't overwrite 'EXTRA_CXX_FLAGS'
(and instead append any additional '--enable-cxx-flags=[...]').

	libstdc++-v3/
	* acinclude.m4 (GLIBCXX_ENABLE_CXX_FLAGS): Append to
	'EXTRA_CXX_FLAGS' any additional flags.
	* configure: Regenerate.
	* configure.host: Document 'EXTRA_CFLAGS', 'EXTRA_CXX_FLAGS'.

(cherry picked from commit 5967fe0dd1f3a49176740553cd147e99d6950895)

diff --git a/libstdc++-v3/ChangeLog.omp b/libstdc++-v3/ChangeLog.omp
index 7ede4aed9664aa2274d6838c4f91f62d58c10038..3cce4e083b1b58149c730bd32902b98a5c8d60e4 100644 (file)
--- a/libstdc++-v3/ChangeLog.omp
+++ b/libstdc++-v3/ChangeLog.omp
@@ -1,5 +1,13 @@
 2025-03-19  Thomas Schwinge  <tschwinge@baylibre.com>
 
+       Backported from trunk:
+       2025-03-13  Thomas Schwinge  <tschwinge@baylibre.com>
+
+       * acinclude.m4 (GLIBCXX_ENABLE_CXX_FLAGS): Append to
+       'EXTRA_CXX_FLAGS' any additional flags.
+       * configure: Regenerate.
+       * configure.host: Document 'EXTRA_CFLAGS', 'EXTRA_CXX_FLAGS'.
+
        Backported from trunk:
        2025-03-06  Jonathan Wakely  <jwakely@redhat.com>
                    Thomas Schwinge  <tschwinge@baylibre.com>

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 51a08bcc8b1d07d8ab9144caf80ba0406ae12fca..1c6d725a13591eb9605c7366d192897ba87e0f81 100644 (file)
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -3267,9 +3267,11 @@ AC_DEFUN([GLIBCXX_ENABLE_CXX_FLAGS], [dnl
             AC_MSG_ERROR([compiler flags start with a -]) ;;
       esac
     done
+
+    # Append the additional flags to any that came from 'configure.host'.
+    EXTRA_CXX_FLAGS="$EXTRA_CXX_FLAGS $enable_cxx_flags"
   fi
 
-  EXTRA_CXX_FLAGS="$enable_cxx_flags"
   AC_MSG_RESULT($EXTRA_CXX_FLAGS)
   AC_SUBST(EXTRA_CXX_FLAGS)
 ])

diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 18053ab7eae6c5c155c0e86b7e4e74827c24a7f0..789c3929f4a5141a625a71ab81a1b0d98c86970b 100755 (executable)
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -19450,9 +19450,11 @@ fi
             as_fn_error $? "compiler flags start with a -" "$LINENO" 5 ;;
       esac
     done
+
+    # Append the additional flags to any that came from 'configure.host'.
+    EXTRA_CXX_FLAGS="$EXTRA_CXX_FLAGS $enable_cxx_flags"
   fi
 
-  EXTRA_CXX_FLAGS="$enable_cxx_flags"
   { $as_echo "$as_me:${as_lineno-$LINENO}: result: $EXTRA_CXX_FLAGS" >&5
 $as_echo "$EXTRA_CXX_FLAGS" >&6; }
 

diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
index 7bc430716168748b96053d0c4d7785268706dd1c..933a43f241c3af4f62980a2dfd50479f7fa79543 100644 (file)
--- a/libstdc++-v3/configure.host
+++ b/libstdc++-v3/configure.host
@@ -61,6 +61,10 @@
 #
 # It possibly modifies the following variables:
 #
+#   EXTRA_CFLAGS           extra flags to pass when compiling C code
+#
+#   EXTRA_CXX_FLAGS        extra flags to pass when compiling C++ code
+#
 #   OPT_LDFLAGS            extra flags to pass when linking the library, of
 #                          the form '-Wl,blah'
 #                          (defaults to empty in acinclude.m4)