[PATCH v2] ar: Add --thin for creating thin archives

[Fangrui Song]

In many ar implementations (FreeBSD, elfutils, etc), ar -T has the
X/Open System Interface specified semantics. Therefore -T for thin
archives is not recommended for portability.

    PR binutils/28759
    * ar.c (long_options): Add --thin.
    (usage) Add --thin. Soft deprecate -T.
    * doc/binutils.texi: Add doc.
    * NEWS: Mention --thin.
    * binutils/testsuite/binutils-all/ar.exp: Add tests.
---
 binutils/NEWS                          |  4 ++++
 binutils/ar.c                          |  4 +++-
 binutils/doc/binutils.texi             | 15 ++++++++++-----
 binutils/testsuite/binutils-all/ar.exp | 17 +++++++++++++++++
 4 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/binutils/NEWS b/binutils/NEWS
index 903f8233b99..d62f019bc82 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -18,6 +18,10 @@
 * Support for efi-app-aarch64, efi-rtdrv-aarch64 and efi-bsdrv-aarch64 has been
   added to objcopy in order to enable UEFI development using binutils.
 
+* ar: Add --thin for creating thin archives. -T is deprecated (no diagnostic)
+  for because in many ar implementations -T has a different meaning from X/Open
+  System Interface.
+
 Changes in 2.37:
 
 * The readelf tool has a new command line option which can be used to specify
diff --git a/binutils/ar.c b/binutils/ar.c
index d7d2fc21dd9..0d4c7cf16a6 100644
--- a/binutils/ar.c
+++ b/binutils/ar.c
@@ -172,6 +172,7 @@ static struct option long_options[] =
   {"version", no_argument, &show_version, 1},
   {"output", required_argument, NULL, OPTION_OUTPUT},
   {"record-libdeps", required_argument, NULL, 'l'},
+  {"thin", no_argument, NULL, 'T'},
   {NULL, no_argument, NULL, 0}
 };
 
@@ -337,13 +338,14 @@ usage (int help)
   fprintf (s, _("  [s]          - create an archive index (cf. ranlib)\n"));
   fprintf (s, _("  [l <text> ]  - specify the dependencies of this library\n"));
   fprintf (s, _("  [S]          - do not build a symbol table\n"));
-  fprintf (s, _("  [T]          - make a thin archive\n"));
+  fprintf (s, _("  [T]          - deprecated, use --thin instead\n"));
   fprintf (s, _("  [v]          - be verbose\n"));
   fprintf (s, _("  [V]          - display the version number\n"));
   fprintf (s, _("  @<file>      - read options from <file>\n"));
   fprintf (s, _("  --target=BFDNAME - specify the target object format as BFDNAME\n"));
   fprintf (s, _("  --output=DIRNAME - specify the output directory for extraction operations\n"));
   fprintf (s, _("  --record-libdeps=<text> - specify the dependencies of this library\n"));
+  fprintf (s, _("  --thin       - make a thin archive\n"));
 #if BFD_SUPPORTS_PLUGINS
   fprintf (s, _(" optional:\n"));
   fprintf (s, _("  --plugin <p> - load the specified plugin\n"));
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 446c275a5db..de1a58e73ad 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -256,7 +256,7 @@ program.
 
 @smallexample
 @c man begin SYNOPSIS ar
-ar [@option{-X32_64}] [@option{-}]@var{p}[@var{mod}] [@option{--plugin} @var{name}] [@option{--target} @var{bfdname}] [@option{--output} @var{dirname}] [@option{--record-libdeps} @var{libdeps}] [@var{relpos}] [@var{count}] @var{archive} [@var{member}@dots{}]
+ar [@option{-X32_64}] [@option{-}]@var{p}[@var{mod}] [@option{--plugin} @var{name}] [@option{--target} @var{bfdname}] [@option{--output} @var{dirname}] [@option{--record-libdeps} @var{libdeps}] [@option{--thin}] [@var{relpos}] [@var{count}] @var{archive} [@var{member}@dots{}]
 @c man end
 @end smallexample
 
@@ -507,10 +507,9 @@ with the linker.  In order to build a symbol table, you must omit the
 @samp{ranlib} on the archive.
 
 @item T
-@cindex creating thin archive
-Make the specified @var{archive} a @emph{thin} archive.  If it already
-exists and is a regular archive, the existing members must be present
-in the same directory as @var{archive}.
+Deprecated alias for @option{--thin}.  @option{T} is not recommended because in
+many ar implementations @option{T} has a different meaning from X/Open System
+Interface.
 
 @item u
 @cindex updating an archive
@@ -603,6 +602,12 @@ line.
 The @option{--record-libdeps} option is identical to the @option{l} modifier,
 just handled in long form.
 
+@item --thin
+@cindex creating thin archive
+Make the specified @var{archive} a @emph{thin} archive.  If it already
+exists and is a regular archive, the existing members must be present
+in the same directory as @var{archive}.
+
 @end table
 @c man end
 
diff --git a/binutils/testsuite/binutils-all/ar.exp b/binutils/testsuite/binutils-all/ar.exp
index 12aa079865b..3b841825f6f 100644
--- a/binutils/testsuite/binutils-all/ar.exp
+++ b/binutils/testsuite/binutils-all/ar.exp
@@ -309,11 +309,13 @@ proc thin_archive_with_nested { bfdtests } {
     if [is_remote host] {
 	set archive artest.a
 	set archive2 artest2.a
+	set archive3 artest3.a
 	set objfile [remote_download host tmpdir/bintest.${obj}]
 	remote_file host delete $archive
     } else {
 	set archive tmpdir/artest.a
 	set archive2 tmpdir/artest2.a
+	set archive3 tmpdir/artest3.a
 	set objfile tmpdir/bintest.${obj}
     }
 
@@ -333,6 +335,14 @@ proc thin_archive_with_nested { bfdtests } {
 	return
     }
 
+    remote_file build delete tmpdir/artest3.a
+
+    set got [binutils_run $AR "rc --thin $archive3 ${archive}"]
+    if ![string match "" $got] {
+	fail $testname
+	return
+    }
+
     foreach bfdtest $bfdtests {
 	set exec_output [binutils_run "$base_dir/$bfdtest" "$archive"]
 	if ![string match "" $exec_output] {
@@ -347,6 +357,13 @@ proc thin_archive_with_nested { bfdtests } {
 	    fail "$testname ($bfdtest)"
 	    return
 	}
+
+	set exec_output [binutils_run "$base_dir/$bfdtest" "$archive3"]
+	if ![string match "" $exec_output] {
+	    verbose -log $exec_output
+	    fail "$testname ($bfdtest)"
+	    return
+	}
     }
 
     set got [binutils_run $NM "--print-armap $archive"]
-- 
2.34.1.575.g55b058a8bb-goog