[glibc/azanella/clang] Use -Wl, --undefined-version if linker requires it

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4be2bf2ea45d2ae01f42f74cab64d5f701d01649

commit 4be2bf2ea45d2ae01f42f74cab64d5f701d01649
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Jan 4 13:46:38 2023 -0300

    Use -Wl,--undefined-version if linker requires it
    
    The lld might set --no-undefined-version as default, which triggers
    a lot of error since the Versions files may contain entries not
    exported by all ABI.
    
    The  -Wl,--undefined-version can not be set by default, since binutils
    ld does not support (although gold does).  So it requires to be checked
    at configure if linker requires and enabled it conditionally.

Diff:
---
 Makeconfig   |  9 ++++++++
 configure    | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac | 27 ++++++++++++++++++++++++
 3 files changed, 104 insertions(+)

diff --git a/Makeconfig b/Makeconfig
index acde47e99c..ce19406b88 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -424,6 +424,15 @@ ifndef after-link
 after-link =
 endif
 
+# The Versions file may contain entries not exported by all ABI, which
+# trigger errors if the linker defaults to --no-undefined-version.  The
+# configure checks whether it is the case and adds --undefined-version
+# if required.
+LDFLAGS-rtld += $(config-ldflags-undefined-version)
+LDFLAGS-lib.so += $(config-ldflags-undefined-version)
+LDFLAGS.so += $(config-ldflags-undefined-version)
+link-extra-flags += $(config-ldflags-undefined-version)
+
 # Additional libraries to link into every test.
 link-extra-libs-tests = $(libsupport)
 
diff --git a/configure b/configure
index db058a78b5..9c577b2bbf 100755
--- a/configure
+++ b/configure
@@ -6924,6 +6924,74 @@ printf "%s\n" "$libc_linker_feature" >&6; }
 config_vars="$config_vars
 have-no-dynamic-linker = $libc_cv_no_dynamic_linker"
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether to suppress unused version in version script" >&5
+printf %s "checking whether to suppress unused version in version script... " >&6; }
+if test ${libc_cv_undefined_version+y}
+then :
+  printf %s "(cached) " >&6
+else $as_nop
+  cat > conftest.c <<EOF
+void foo (void) { }
+EOF
+cat > conftest.map <<EOF
+VER_1.0 {
+  global:
+    bar;
+};
+EOF
+libc_cv_undefined_version=""
+if ! { ac_try='${CC-cc} -nostdlib -nostartfiles $no_ssp -fPIC -shared -Wl,--version-script=conftest.map conftest.c -o conftest.so'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; };
+then
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for linker that supports --undefined-version" >&5
+printf %s "checking for linker that supports --undefined-version... " >&6; }
+libc_linker_feature=no
+cat > conftest.c <<EOF
+int _start (void) { return 42; }
+EOF
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
+		  -Wl,--undefined-version -nostdlib -nostartfiles
+		  -fPIC -shared -o conftest.so conftest.c
+		  1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,--undefined-version -nostdlib \
+      -nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \
+      | grep "warning: --undefined-version ignored" > /dev/null 2>&1; then
+    true
+  else
+    libc_linker_feature=yes
+  fi
+fi
+rm -f conftest*
+if test $libc_linker_feature = yes; then
+  libc_cv_support_undefined_version=yes
+else
+  libc_cv_support_undefined_version=no
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5
+printf "%s\n" "$libc_linker_feature" >&6; }
+  if test "$libc_cv_support_undefined_version" = no; then
+    as_fn_error $? "support for -Wl,--undefined-version required" "$LINENO" 5
+  fi
+  libc_cv_undefined_version="-Wl,--undefined-version"
+fi
+rm -f conftest.*t
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_undefined_version" >&5
+printf "%s\n" "$libc_cv_undefined_version" >&6; }
+config_vars="$config_vars
+config-ldflags-undefined-version = $libc_cv_undefined_version"
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for -static-pie" >&5
 printf %s "checking for -static-pie... " >&6; }
 if test ${libc_cv_static_pie+y}
diff --git a/configure.ac b/configure.ac
index d8b1843593..f0ef446df3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1251,6 +1251,33 @@ LIBC_LINKER_FEATURE([--no-dynamic-linker],
 		    [libc_cv_no_dynamic_linker=no])
 LIBC_CONFIG_VAR([have-no-dynamic-linker], [$libc_cv_no_dynamic_linker])
 
+AC_CACHE_CHECK(whether to suppress unused version in version script,
+	       libc_cv_undefined_version, [dnl
+cat > conftest.c <<EOF
+void foo (void) { }
+EOF
+cat > conftest.map <<EOF
+VER_1.0 {
+  global:
+    bar;
+};
+EOF
+libc_cv_undefined_version=""
+if ! AC_TRY_COMMAND([${CC-cc} -nostdlib -nostartfiles $no_ssp -fPIC -shared -Wl,--version-script=conftest.map conftest.c -o conftest.so]);
+then
+  LIBC_LINKER_FEATURE([--undefined-version],
+		      [-Wl,--undefined-version],
+		      [libc_cv_support_undefined_version=yes],
+		      [libc_cv_support_undefined_version=no])
+  if test "$libc_cv_support_undefined_version" = no; then
+    AC_MSG_ERROR([support for -Wl,--undefined-version required])
+  fi
+  libc_cv_undefined_version="-Wl,--undefined-version"
+fi
+rm -f conftest.*t])
+LIBC_CONFIG_VAR([config-ldflags-undefined-version],[$libc_cv_undefined_version])
+
+
 AC_CACHE_CHECK(for -static-pie, libc_cv_static_pie, [dnl
 LIBC_TRY_CC_OPTION([-static-pie],
 		   [libc_cv_static_pie=yes],