From da326568ef8b64721f080060aa7f1783bcb8991f Mon Sep 17 00:00:00 2001
From: Adam Turner <9087854+aa-turner@users.noreply.github.com>
Date: Wed, 7 May 2025 10:35:54 +0100
Subject: [PATCH] Restore libzstd fallback detection

---
 configure     | 290 ++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac  |  28 ++++-
 pyconfig.h.in |   6 ++
 3 files changed, 323 insertions(+), 1 deletion(-)

diff --git a/configure b/configure
index c51192f12c8223..a43f1f84d046b8 100755
--- a/configure
+++ b/configure
@@ -22451,11 +22451,301 @@ fi
         # Put the nasty error message in config.log where it belongs
         echo "$LIBZSTD_PKG_ERRORS" >&5
 
+
+  save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+    CPPFLAGS="$CPPFLAGS $LIBZSTD_CFLAGS"
+    CFLAGS="$CFLAGS $LIBZSTD_CFLAGS"
+    LIBS="$LIBS $LIBZSTD_LIBS"
+    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for library containing ZDICT_finalizeDictionary" >&5
+printf %s "checking for library containing ZDICT_finalizeDictionary... " >&6; }
+if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char ZDICT_finalizeDictionary (void);
+int
+main (void)
+{
+return ZDICT_finalizeDictionary ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' zstd
+do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_search_ZDICT_finalizeDictionary=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext
+  if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+  break
+fi
+done
+if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+
+else case e in #(
+  e) ac_cv_search_ZDICT_finalizeDictionary=no ;;
+esac
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_ZDICT_finalizeDictionary" >&5
+printf "%s\n" "$ac_cv_search_ZDICT_finalizeDictionary" >&6; }
+ac_res=$ac_cv_search_ZDICT_finalizeDictionary
+if test "$ac_res" != no
+then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking ZSTD_VERSION_NUMBER >= 1.4.5" >&5
+printf %s "checking ZSTD_VERSION_NUMBER >= 1.4.5... " >&6; }
+      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+        #include "zstd.h"
+int
+main (void)
+{
+
+          #if ZSTD_VERSION_NUMBER < 10405
+          #  error "zstd version is too old"
+          #endif
+
+  ;
+  return 0;
+}
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+               for ac_header in zstd.h zdict.h
+do :
+  as_ac_Header=`printf "%s\n" "ac_cv_header_$ac_header" | sed "$as_sed_sh"`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"
+then :
+  cat >>confdefs.h <<_ACEOF
+#define `printf "%s\n" "HAVE_$ac_header" | sed "$as_sed_cpp"` 1
+_ACEOF
+ have_libzstd=yes
+else case e in #(
+  e) have_libzstd=no ;;
+esac
+fi
+
+done
+
+else case e in #(
+  e)
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
         have_libzstd=no
+       ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+
+else case e in #(
+  e) have_libzstd=no ;;
+esac
+fi
+
+    if test "x$have_libzstd" = xyes
+then :
+
+      LIBZSTD_CFLAGS=${LIBZSTD_CFLAGS-""}
+      LIBZSTD_LIBS=${LIBZSTD_LIBS-"-lzstd"}
+
+fi
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
+
 elif test $pkg_failed = untried; then
         { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
+
+  save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+    CPPFLAGS="$CPPFLAGS $LIBZSTD_CFLAGS"
+    CFLAGS="$CFLAGS $LIBZSTD_CFLAGS"
+    LIBS="$LIBS $LIBZSTD_LIBS"
+    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for library containing ZDICT_finalizeDictionary" >&5
+printf %s "checking for library containing ZDICT_finalizeDictionary... " >&6; }
+if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char ZDICT_finalizeDictionary (void);
+int
+main (void)
+{
+return ZDICT_finalizeDictionary ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' zstd
+do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_search_ZDICT_finalizeDictionary=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext
+  if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+  break
+fi
+done
+if test ${ac_cv_search_ZDICT_finalizeDictionary+y}
+then :
+
+else case e in #(
+  e) ac_cv_search_ZDICT_finalizeDictionary=no ;;
+esac
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_ZDICT_finalizeDictionary" >&5
+printf "%s\n" "$ac_cv_search_ZDICT_finalizeDictionary" >&6; }
+ac_res=$ac_cv_search_ZDICT_finalizeDictionary
+if test "$ac_res" != no
+then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking ZSTD_VERSION_NUMBER >= 1.4.5" >&5
+printf %s "checking ZSTD_VERSION_NUMBER >= 1.4.5... " >&6; }
+      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+        #include "zstd.h"
+int
+main (void)
+{
+
+          #if ZSTD_VERSION_NUMBER < 10405
+          #  error "zstd version is too old"
+          #endif
+
+  ;
+  return 0;
+}
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; }
+               for ac_header in zstd.h zdict.h
+do :
+  as_ac_Header=`printf "%s\n" "ac_cv_header_$ac_header" | sed "$as_sed_sh"`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"
+then :
+  cat >>confdefs.h <<_ACEOF
+#define `printf "%s\n" "HAVE_$ac_header" | sed "$as_sed_cpp"` 1
+_ACEOF
+ have_libzstd=yes
+else case e in #(
+  e) have_libzstd=no ;;
+esac
+fi
+
+done
+
+else case e in #(
+  e)
+        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
+printf "%s\n" "no" >&6; }
         have_libzstd=no
+       ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+
+else case e in #(
+  e) have_libzstd=no ;;
+esac
+fi
+
+    if test "x$have_libzstd" = xyes
+then :
+
+      LIBZSTD_CFLAGS=${LIBZSTD_CFLAGS-""}
+      LIBZSTD_LIBS=${LIBZSTD_LIBS-"-lzstd"}
+
+fi
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
+
 else
         LIBZSTD_CFLAGS=$pkg_cv_LIBZSTD_CFLAGS
         LIBZSTD_LIBS=$pkg_cv_LIBZSTD_LIBS
diff --git a/configure.ac b/configure.ac
index a7b2f62579b0e9..e3f39f19fc23e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5387,7 +5387,33 @@ PKG_CHECK_MODULES([LIBLZMA], [liblzma], [have_liblzma=yes], [
 ])
 
 dnl zstd 1.4.5 stabilised ZDICT_finalizeDictionary
-PKG_CHECK_MODULES([LIBZSTD], [libzstd >= 1.4.5], [have_libzstd=yes], [have_libzstd=no])
+PKG_CHECK_MODULES([LIBZSTD], [libzstd >= 1.4.5], [have_libzstd=yes], [
+  WITH_SAVE_ENV([
+    CPPFLAGS="$CPPFLAGS $LIBZSTD_CFLAGS"
+    CFLAGS="$CFLAGS $LIBZSTD_CFLAGS"
+    LIBS="$LIBS $LIBZSTD_LIBS"
+    AC_SEARCH_LIBS([ZDICT_finalizeDictionary], [zstd], [
+      AC_MSG_CHECKING([ZSTD_VERSION_NUMBER >= 1.4.5])
+      AC_COMPILE_IFELSE([
+        AC_LANG_PROGRAM([@%:@include "zstd.h"], [
+          #if ZSTD_VERSION_NUMBER < 10405
+          #  error "zstd version is too old"
+          #endif
+        ])
+      ], [
+        AC_MSG_RESULT([yes])
+        AC_CHECK_HEADERS([zstd.h zdict.h], [have_libzstd=yes], [have_libzstd=no])
+      ], [
+        AC_MSG_RESULT([no])
+        have_libzstd=no
+      ])
+    ], [have_libzstd=no])
+    AS_VAR_IF([have_libzstd], [yes], [
+      LIBZSTD_CFLAGS=${LIBZSTD_CFLAGS-""}
+      LIBZSTD_LIBS=${LIBZSTD_LIBS-"-lzstd"}
+    ])
+  ])
+])
 
 dnl PY_CHECK_NETDB_FUNC(FUNCTION)
 AC_DEFUN([PY_CHECK_NETDB_FUNC], [PY_CHECK_FUNC([$1], [@%:@include <netdb.h>])])
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 7586ad3f266705..c91facbedf94e5 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -1630,12 +1630,18 @@
 /* Define to 1 if you have the 'writev' function. */
 #undef HAVE_WRITEV
 
+/* Define to 1 if you have the <zdict.h> header file. */
+#undef HAVE_ZDICT_H
+
 /* Define if the zlib library has inflateCopy */
 #undef HAVE_ZLIB_COPY
 
 /* Define to 1 if you have the <zlib.h> header file. */
 #undef HAVE_ZLIB_H
 
+/* Define to 1 if you have the <zstd.h> header file. */
+#undef HAVE_ZSTD_H
+
 /* Define to 1 if you have the '_getpty' function. */
 #undef HAVE__GETPTY