From baf65b91c51bb04b09ecc98b94ddd4ba3b446912 Mon Sep 17 00:00:00 2001
From: David Allsopp <david.allsopp@metastack.com>
Date: Sat, 20 Apr 2024 07:33:25 +0100
Subject: [PATCH] Merge pull request #13100 from dra27/zstd-runs

Fix detection of zstd when compiling with musl-gcc

(cherry picked from commit d784a6951fdb97fd7531d1c5efee45f6291447fb)
---
 configure    | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac | 38 ++++++++++++++++++++++++
 2 files changed, 122 insertions(+)

diff --git a/configure b/configure
index d36802ae9823ce36b50ca4733fe4d502a39f0f36..b45d5873a5aafebf58af98a765c22057a6b97d91 100755
--- a/configure
+++ b/configure
@@ -18303,6 +18303,90 @@ fi
 fi
 fi
 
+# When building the mingw-w64 port in Cygwin, it is very easy to have the
+# library available, but not have the DLL in PATH. This then causes the build to
+# fail as soon as ocamlrun is first executed. This check avoids automatically
+# enabling zstd when the resulting executable doesn't actually work.
+case $host in #(
+  *-w64-mingw32*|*-pc-windows) :
+    check_zstd_runs=$host_runnable ;; #(
+  *) :
+    check_zstd_runs=false ;;
+esac
+
+if test x"$zstd_status" = "xok"
+then :
+
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether programs can be linked with zstd" >&5
+printf %s "checking whether programs can be linked with zstd... " >&6; }
+
+  saved_CC="$CC"
+  saved_CFLAGS="$CFLAGS"
+  saved_CPPFLAGS="$CPPFLAGS"
+  saved_LIBS="$LIBS"
+  saved_ac_ext="$ac_ext"
+  saved_ac_compile="$ac_compile"
+  # Move the content of confdefs.h to another file so it does not
+  # get included
+  mv confdefs.h confdefs.h.bak
+  touch confdefs.h
+
+  LIBS="$LIBS $zstd_libs"
+  CFLAGS="$CFLAGS $zstd_flags"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <zstd.h>
+int main(void) {
+  return (ZSTD_versionNumber() == 0);
+}
+
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether programs linked with zstd can execute" >&5
+printf %s "checking whether programs linked with zstd can execute... " >&6; }
+    if $check_zstd_runs
+then :
+  if ac_fn_c_try_run LINENO
+then :
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+        zstd_libs=''
+        zstd_flags=''
+        zstd_status=\
+"programs linked with zstd do not appear to be executable."
+fi
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: skipped" >&5
+printf "%s\n" "skipped" >&6; }
+fi
+else $as_nop
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
+    zstd_libs=''
+    zstd_flags=''
+    zstd_status="zstd found, but programs cannot be linked with it."
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+
+  # Restore the content of confdefs.h
+  mv confdefs.h.bak confdefs.h
+  ac_compile="$saved_ac_compile"
+  ac_ext="$saved_ac_ext"
+  CPPFLAGS="$saved_CPPFLAGS"
+  CFLAGS="$saved_CFLAGS"
+  CC="$saved_CC"
+  LIBS="$saved_LIBS"
+
+fi
+
 if test x"$zstd_status" = "xok"
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: compressed compilation artefacts supported" >&5
diff --git a/configure.ac b/configure.ac
index b81da53c4292f464967575958bb69a00bd7f1907..041885d6deb1ee2de8ff8ec4a2aecb85f6b47bb0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1995,6 +1995,44 @@ AS_IF([test x"$with_zstd" != "xno"],
         [[#include <zstd.h>]])],
       [zstd_status="zstd library not found"])]))
 
+# When building the mingw-w64 port in Cygwin, it is very easy to have the
+# library available, but not have the DLL in PATH. This then causes the build to
+# fail as soon as ocamlrun is first executed. This check avoids automatically
+# enabling zstd when the resulting executable doesn't actually work.
+AS_CASE([$host],
+  [*-w64-mingw32*|*-pc-windows],
+    [check_zstd_runs=$host_runnable],
+  [check_zstd_runs=false])
+
+AS_IF([test x"$zstd_status" = "xok"],[
+  AC_MSG_CHECKING([whether programs can be linked with zstd])
+  OCAML_CC_SAVE_VARIABLES
+  LIBS="$LIBS $zstd_libs"
+  CFLAGS="$CFLAGS $zstd_flags"
+  AC_LINK_IFELSE(
+    [AC_LANG_SOURCE([[
+#include <zstd.h>
+int main(void) {
+  return (ZSTD_versionNumber() == 0);
+}
+    ]])],
+    [AC_MSG_RESULT([yes])
+    AC_MSG_CHECKING([whether programs linked with zstd can execute])
+    AS_IF([$check_zstd_runs],
+      [AS_IF([ac_fn_c_try_run LINENO],
+        [AC_MSG_RESULT([yes])],
+        [AC_MSG_RESULT([no])
+        zstd_libs=''
+        zstd_flags=''
+        zstd_status=\
+"programs linked with zstd do not appear to be executable."])],
+      [AC_MSG_RESULT([skipped])])],
+    [AC_MSG_RESULT([no])
+    zstd_libs=''
+    zstd_flags=''
+    zstd_status="zstd found, but programs cannot be linked with it."])
+  OCAML_CC_RESTORE_VARIABLES])
+
 AS_IF([test x"$zstd_status" = "xok"],
   [AC_MSG_NOTICE([compressed compilation artefacts supported])
    internal_cppflags="$internal_cppflags $zstd_flags"