[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=f1432adaccce08aa67bec2434f75a0956b94319c

commit f1432adaccce08aa67bec2434f75a0956b94319c
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 a908d3e19d..bf6d610a55 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 965c28a776..f593aeb9fe 100755
--- a/configure
+++ b/configure
@@ -7049,6 +7049,74 @@ 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 ${libc_cv_static_pie+y}
diff --git a/configure.ac b/configure.ac
index 6e9b133110..8782cf8729 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1316,6 +1316,33 @@ LIBC_LINKER_FEATURE([--no-dynamic-linker],
 		    [libc_cv_no_dynamic_linker=no])
 LIBC_CONFIG_VAR([have-no-dynamic-linker], [$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],