[PATCH] ELF: Hide symbols defined in discarded input sections

[H.J. Lu]

When assigning symbol version, we should hide debug symbols defined in
discarded sections from IR objects so that they can be removed later.

bfd/

	PR ld/23818
	* elflink.c (_bfd_elf_link_assign_sym_version): Hide symbols
	defined in discarded input sections.

ld/

	PR ld/23818
	* testsuite/ld-plugin/lto.exp: Run PR ld/23818 test.
	* testsuite/ld-plugin/pr23818.d: New file.
	* testsuite/ld-plugin/pr23818.t: Likewise.
	* testsuite/ld-plugin/pr23818a.c: Likewise.
	* testsuite/ld-plugin/pr23818b.c: Likewise.
---
 bfd/elflink.c                     | 12 ++++++++++--
 ld/testsuite/ld-plugin/lto.exp    |  6 ++++++
 ld/testsuite/ld-plugin/pr23818.d  |  4 ++++
 ld/testsuite/ld-plugin/pr23818.t  |  4 ++++
 ld/testsuite/ld-plugin/pr23818a.c |  4 ++++
 ld/testsuite/ld-plugin/pr23818b.c |  7 +++++++
 6 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 ld/testsuite/ld-plugin/pr23818.d
 create mode 100644 ld/testsuite/ld-plugin/pr23818.t
 create mode 100644 ld/testsuite/ld-plugin/pr23818a.c
 create mode 100644 ld/testsuite/ld-plugin/pr23818b.c

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 87440db960..4eca389bd1 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -2359,13 +2359,21 @@ _bfd_elf_link_assign_sym_version (struct elf_link_hash_entry *h, void *data)
       return FALSE;
     }
 
+  bed = get_elf_backend_data (info->output_bfd);
+
   /* We only need version numbers for symbols defined in regular
      objects.  */
   if (!h->def_regular)
-    return TRUE;
+    {
+      /* Hide symbols defined in discarded input sections.  */
+      if ((h->root.type == bfd_link_hash_defined
+	   || h->root.type == bfd_link_hash_defweak)
+	  && discarded_section (h->root.u.def.section))
+	(*bed->elf_backend_hide_symbol) (info, h, TRUE);
+      return TRUE;
+    }
 
   hide = FALSE;
-  bed = get_elf_backend_data (info->output_bfd);
   p = strchr (h->root.root.string, ELF_VER_CHR);
   if (p != NULL && h->verinfo.vertree == NULL)
     {
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 18829fdd64..008bde79de 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -219,6 +219,12 @@ set lto_link_tests [list \
   [list "Build pr22751.a" \
    "$plug_opt" "-flto $lto_no_fat $INT128_CFLAGS" \
    {pr22751.c} {} "pr22751.a"] \
+  [list "Build libpr23818.so" \
+   "-shared -flto -g -Wl,-version-script,pr23818.t" \
+   "-g -flto $lto_fat" \
+   {pr23818a.c pr23818b.c} \
+   {{"readelf" {-s --wide} "pr23818.d"}} \
+   "libpr23818.so"] \
 ]
 
 if { [at_least_gcc_version 4 7] } {
diff --git a/ld/testsuite/ld-plugin/pr23818.d b/ld/testsuite/ld-plugin/pr23818.d
new file mode 100644
index 0000000000..5753cd64fd
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr23818.d
@@ -0,0 +1,4 @@
+#failif
+#...
+.*0+ +[A-Z]+ +GLOBAL +DEFAULT +ABS foo
+#...
diff --git a/ld/testsuite/ld-plugin/pr23818.t b/ld/testsuite/ld-plugin/pr23818.t
new file mode 100644
index 0000000000..45bca5580e
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr23818.t
@@ -0,0 +1,4 @@
+{
+  global: bar;
+  local: *;
+};
diff --git a/ld/testsuite/ld-plugin/pr23818a.c b/ld/testsuite/ld-plugin/pr23818a.c
new file mode 100644
index 0000000000..5b5ccbf7cb
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr23818a.c
@@ -0,0 +1,4 @@
+void
+foo ()
+{
+}
diff --git a/ld/testsuite/ld-plugin/pr23818b.c b/ld/testsuite/ld-plugin/pr23818b.c
new file mode 100644
index 0000000000..d4be333a39
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr23818b.c
@@ -0,0 +1,7 @@
+void foo (void);
+
+void
+bar (void)
+{
+  foo ();
+}
-- 
2.17.2