[gcc r17-3286] libgomp: Revise libgomp/Fortran support conditionals

https://gcc.gnu.org/g:e5efa9eff99da897f0bbd69455d8f7856985b2db

commit r17-3286-ge5efa9eff99da897f0bbd69455d8f7856985b2db
Author: Thomas Schwinge <[email protected]>
Date:   Tue Jul 28 20:46:16 2026 +0200

    libgomp: Revise libgomp/Fortran support conditionals
    
    Subversion r152931 (Git commit 0046b1a727f73f0848733e28219069426b2dc218)
    "Fix libgomp without --enable-languages=fortran", and its follow-up
    Subversion r156232 (Git commit d0709b6aeec6b00e71011502fa311751fc138147)
    "configure.ac: Test for executability of GFORTRAN",
    Subversion r156264 (Git commit 2122aa973ed2c829caee5b010a60ad01922a3650)
    "configure.ac: Test for executability of _the first word_ of GFORTRAN"
    fixed the libgomp target library build in case that
    '--enable-languages=fortran' was not in effect: in that case, disable
    libgomp/Fortran support.
    
    These changes certainly do the right thing in GCC configurations where
    '$GFORTRAN' would be expected to be "just compiled" (built with the GCC
    top-level build system).  However, in case that it's "pre-installed" (provided
    externally, as determined by the GCC top-level build system), these changes
    didn't work, and instead kept libgomp/Fortran support disabled, instead of
    enabling it.  "Pre-installed" 'GFORTRAN="x86_64-w64-mingw32-gfortran [...]"' is
    not accepted by the current 'test -x [...]' check, for instance, as discussed
    in "libgomp: Fix gfortran detection when program is found via PATH",
    <https://inbox.sourceware.org/[email protected]>
    <https://forge.sourceware.org/gcc/gcc/pulls/172>,
    <https://inbox.sourceware.org/bmm.hj9f44xa6a.gcc.gcc-TEST.Peter0x44.172.1.0@forge-stage.sourceware.org>.
    
    That proposed "libgomp: Fix gfortran detection when program is found via PATH"
    patch has the issue that it picks up the "gfortran [...] found via PATH" also
    in the case when GCC is configured without '--enable-languages=fortran' in
    effect, and it then still builds and installs the libgomp/Fortran support files
    in GCC configurations without Fortran support enabled.
    
    Instead of "libgomp: Fix gfortran detection when program is found via PATH" as
    proposed, we may revise libgomp/Fortran support conditionals generally, and
    handle that in a conceptually simpler way: revert the three aforementioned
    commits (in other words: simply again assign 'FC="$GFORTRAN"' (like
    'libgfortran/configure.ac' also is doing), and conditionalize 'USE_FORTRAN' on
    whether '--enable-languages=fortran' is in effect.  In other words: in case
    that '--enable-languages=fortran' is in effect, assume that the
    'GFORTRAN=[...]' passed to the libgomp build is functional -- no matter where
    it's coming from: "just compiled" or "pre-installed".
    
            PR libgomp/41418
            libgomp/
            * configure.ac (FC): Revert ealier changes; just set to '"$GFORTRAN"'.
            (USE_FORTRAN): Conditionalize on '--enable-languages=fortran' being in
            effect.
            * configure: Regenerate.
    
    Reported-by: Peter Damianov <[email protected]>

Diff:
---
 libgomp/configure    | 50 ++++++++++++++++++++++++--------------------------
 libgomp/configure.ac | 24 +++++++++++-------------
 2 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/libgomp/configure b/libgomp/configure
index 2f395a883f2a..6ff3899df153 100755
--- a/libgomp/configure
+++ b/libgomp/configure
@@ -649,8 +649,6 @@ OMP_NEST_LOCK_SIZE
 OMP_LOCK_ALIGN
 OMP_LOCK_SIZE
 INTPTR_T_KIND
-USE_FORTRAN_FALSE
-USE_FORTRAN_TRUE
 link_gomp
 tmake_file
 XLDFLAGS
@@ -677,6 +675,8 @@ offload_targets
 offload_plugins
 DL_LIBS
 libtool_VERSION
+USE_FORTRAN_FALSE
+USE_FORTRAN_TRUE
 ac_ct_FC
 FCFLAGS
 FC
@@ -12265,17 +12265,7 @@ FCFLAGS="$FCFLAGS -L."
 # We need gfortran to compile parts of the library
 # We can't use AC_PROG_FC because it expects a fully working gfortran.
 #AC_PROG_FC(gfortran)
-case `echo $GFORTRAN` in
-  -* | no* )
-    FC=no ;;
-  *)
-    set dummy $GFORTRAN; ac_word=$2
-    if test -x "$ac_word"; then
-      FC="$GFORTRAN"
-    else
-      FC=no
-    fi ;;
-esac
+FC="$GFORTRAN"
 ac_ext=${ac_fc_srcext-f}
 ac_compile='$FC -c $FCFLAGS $ac_fcflags_srcext conftest.$ac_ext >&5'
 ac_link='$FC -o conftest$ac_exeext $FCFLAGS $LDFLAGS $ac_fcflags_srcext conftest.$ac_ext $LIBS >&5'
@@ -15241,6 +15231,23 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 FCFLAGS="$FCFLAGS -Wall -L../libgfortran"
 
+case ,${enable_languages}, in
+  *,fortran,* )
+   use_fortran=true
+   ;;
+  * )
+   use_fortran=false
+   ;;
+esac
+ if "$use_fortran"; then
+  USE_FORTRAN_TRUE=
+  USE_FORTRAN_FALSE='#'
+else
+  USE_FORTRAN_TRUE='#'
+  USE_FORTRAN_FALSE=
+fi
+
+
 # For libtool versioning info, format is CURRENT:REVISION:AGE
 libtool_VERSION=1:0:0
 
@@ -17351,15 +17358,6 @@ else
 fi
 
 
- if test "$ac_cv_fc_compiler_gnu" = yes; then
-  USE_FORTRAN_TRUE=
-  USE_FORTRAN_FALSE='#'
-else
-  USE_FORTRAN_TRUE='#'
-  USE_FORTRAN_FALSE=
-fi
-
-
 # ??? 2006-01-24: Paulo committed to asking autoconf folk to document
 # and export AC_COMPUTE_INT.  If that happens, then we'll need to remove
 # the underscore here and update the PREREQ.  If it doesn't, then we'll
@@ -17646,6 +17644,10 @@ if test -z "${MAINTAINER_MODE_TRUE}" && test -z "${MAINTAINER_MODE_FALSE}"; then
   as_fn_error $? "conditional \"MAINTAINER_MODE\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${USE_FORTRAN_TRUE}" && test -z "${USE_FORTRAN_FALSE}"; then
+  as_fn_error $? "conditional \"USE_FORTRAN\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${PLUGIN_NVPTX_TRUE}" && test -z "${PLUGIN_NVPTX_FALSE}"; then
   as_fn_error $? "conditional \"PLUGIN_NVPTX\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
@@ -17666,10 +17668,6 @@ if test -z "${LIBGOMP_BUILD_VERSIONED_SHLIB_SUN_TRUE}" && test -z "${LIBGOMP_BUI
   as_fn_error $? "conditional \"LIBGOMP_BUILD_VERSIONED_SHLIB_SUN\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
-if test -z "${USE_FORTRAN_TRUE}" && test -z "${USE_FORTRAN_FALSE}"; then
-  as_fn_error $? "conditional \"USE_FORTRAN\" was never defined.
-Usually this means the macro was only invoked conditionally." "$LINENO" 5
-fi
 
 : "${CONFIG_STATUS=./config.status}"
 ac_write_fail=0
diff --git a/libgomp/configure.ac b/libgomp/configure.ac
index 057debe92141..9ebac1fc3365 100644
--- a/libgomp/configure.ac
+++ b/libgomp/configure.ac
@@ -159,20 +159,20 @@ FCFLAGS="$FCFLAGS -L."
 # We need gfortran to compile parts of the library
 # We can't use AC_PROG_FC because it expects a fully working gfortran.
 #AC_PROG_FC(gfortran)
-case `echo $GFORTRAN` in
-  -* | no* )
-    FC=no ;;
-  *)
-    set dummy $GFORTRAN; ac_word=$2
-    if test -x "$ac_word"; then
-      FC="$GFORTRAN"
-    else
-      FC=no
-    fi ;;
-esac
+FC="$GFORTRAN"
 AC_PROG_FC(gfortran)
 FCFLAGS="$FCFLAGS -Wall -L../libgfortran"
 
+case ,${enable_languages}, in
+  *,fortran,* )
+   use_fortran=true
+   ;;
+  * )
+   use_fortran=false
+   ;;
+esac
+AM_CONDITIONAL([USE_FORTRAN], ["$use_fortran"])
+
 # For libtool versioning info, format is CURRENT:REVISION:AGE
 libtool_VERSION=1:0:0
 AC_SUBST(libtool_VERSION)
@@ -427,8 +427,6 @@ else
 fi
 AC_SUBST(link_gomp)
 
-AM_CONDITIONAL([USE_FORTRAN], [test "$ac_cv_fc_compiler_gnu" = yes])
-
 # ??? 2006-01-24: Paulo committed to asking autoconf folk to document
 # and export AC_COMPUTE_INT.  If that happens, then we'll need to remove
 # the underscore here and update the PREREQ.  If it doesn't, then we'll