hadrian: Produce ar archives with L modifier on Windows

Since object files may in fact be archive files, we must ensure that
their contents are merged rather than constructing an
archive-of-an-archive.

See #21068.

1 files changed, 30 insertions, 0 deletions

diff --git a/m4/fp_prog_ar_supports_dash_l.m4 b/m4/fp_prog_ar_supports_dash_l.m4
new file mode 100644
index 0000000000..3ec26db548
--- /dev/null
+++ b/m4/fp_prog_ar_supports_dash_l.m4
@@ -0,0 +1,30 @@
+# FP_PROG_AR_SUPPORTS_DASH_L
+# -----------------
+# Sets fp_prog_ar_supports_dash_l to yes or no, depending on whether
+# or not it supports the llvm-ar's -L flag to merge archives.
+AC_DEFUN([FP_PROG_AR_SUPPORTS_DASH_L],
+[
+  AC_REQUIRE([FP_PROG_AR])
+  AC_REQUIRE([FP_PROG_AR_ARGS])
+  AC_CACHE_CHECK([whether $fp_prog_ar supports -L], [fp_cv_prog_ar_supports_dash_l],
+    [
+      rm -f conftest*
+      touch conftest.file
+      touch conftest.a0 conftest.a1 conftest.b0 conftest.b1
+      dnl Build two archives, merge them, and check that the result contains the
+      dnl original files not the two archives.
+      "$fp_prog_ar" qc conftest-a.a conftest.a0 conftest.a1
+      "$fp_prog_ar" qc conftest-b.a conftest.b0 conftest.b1
+      "$fp_prog_ar" qcL conftest.a conftest-a.a conftest-b.a 2>/dev/null
+      if "$fp_prog_ar" t conftest.a | grep -s "conftest.a1" > /dev/null
+      then
+        fp_cv_prog_ar_supports_dash_l=yes
+      else
+        fp_cv_prog_ar_supports_dash_l=no
+      fi
+      rm -f conftest*
+    ])
+  fp_prog_ar_supports_dash_l=$fp_cv_prog_ar_supports_dash_l
+  AC_SUBST([ArSupportsDashL], [`echo $fp_prog_ar_supports_dash_l | tr 'a-z' 'A-Z'`])
+])# FP_PROG_AR_SUPPORTS_DASH_L
+