bpo-45847: Don't override user overrides for CFLAGS/LIBS (GH-29967)

3 files changed, 85 insertions, 67 deletions

diff --git a/configure b/configure
index 8ba76bf..444dd67 100755
--- a/configure
+++ b/configure
@@ -10538,8 +10538,8 @@ if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
 _ACEOF
 
     have_uuid=yes
-    LIBUUID_CFLAGS=
-    LIBUUID_LIBS=
+    LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+    LIBUUID_LIBS=${LIBUUID_LIBS-""}
 
 fi
 done
@@ -10612,8 +10612,6 @@ fi
 	echo "$LIBUUID_PKG_ERRORS" >&5
 
 
-      LIBUUID_LIBS="-luuid"
-      LIBUUID_CFLAGS=
       for ac_header in uuid/uuid.h
 do :
   ac_fn_c_check_header_mongrel "$LINENO" "uuid/uuid.h" "ac_cv_header_uuid_uuid_h" "$ac_includes_default"
@@ -10731,6 +10729,12 @@ LDFLAGS=$save_LDFLAGS
 LIBS=$save_LIBS
 
 
+        if test "x$have_uuid" = xyes; then :
+
+          LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+          LIBUUID_LIBS=${LIBUUID_LIBS-"-luuid"}
+
+fi
 
 fi
 
@@ -10742,8 +10746,6 @@ elif test $pkg_failed = untried; then
      	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
-      LIBUUID_LIBS="-luuid"
-      LIBUUID_CFLAGS=
       for ac_header in uuid/uuid.h
 do :
   ac_fn_c_check_header_mongrel "$LINENO" "uuid/uuid.h" "ac_cv_header_uuid_uuid_h" "$ac_includes_default"
@@ -10861,6 +10863,12 @@ LDFLAGS=$save_LDFLAGS
 LIBS=$save_LIBS
 
 
+        if test "x$have_uuid" = xyes; then :
+
+          LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+          LIBUUID_LIBS=${LIBUUID_LIBS-"-luuid"}
+
+fi
 
 fi
 
@@ -10898,8 +10906,8 @@ _ACEOF
 if test "x$ac_cv_func_uuid_generate_time" = xyes; then :
 
       have_uuid=yes
-      LIBUUID_CFLAGS=
-      LIBUUID_LIBS=
+      LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+      LIBUUID_LIBS=${LIBUUID_LIBS-""}
 
 fi
 
@@ -11350,8 +11358,8 @@ $as_echo "$with_system_expat" >&6; }
 
 if test "x$with_system_expat" = xyes; then :
 
-  LIBEXPAT_CFLAGS=""
-  LIBEXPAT_LDFLAGS="-lexpat"
+  LIBEXPAT_CFLAGS=${LIBEXPAT_CFLAGS-""}
+  LIBEXPAT_LDFLAGS=${LIBEXPAT_LDFLAGS-"-lexpat"}
   LIBEXPAT_INTERNAL=
 
 else
@@ -11424,8 +11432,8 @@ $as_echo "$with_system_libmpdec" >&6; }
 
 if test "x$with_system_libmpdec" = xyes; then :
 
-  LIBMPDEC_CFLAGS=""
-  LIBMPDEC_LDFLAGS="-lmpdec"
+  LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
+  LIBMPDEC_LDFLAGS=${LIBMPDEC_LDFLAGS-"-lmpdec"}
   LIBMPDEC_INTERNAL=
 
 else
@@ -11600,7 +11608,7 @@ fi
 	echo "$LIBNSL_PKG_ERRORS" >&5
 
 
-  LIBNSL_CFLAGS=
+  LIBNSL_CFLAGS=${LIBNSL_CFLAGS-""}
   save_CFLAGS=$CFLAGS
 save_CPPFLAGS=$CPPFLAGS
 save_LDFLAGS=$LDFLAGS
@@ -11674,19 +11682,20 @@ LIBS=$save_LIBS
 
   case $ac_cv_search_yp_match in #(
   no) :
-    LIBNSL_LIBS= ;; #(
+    libnsl="" ;; #(
   "none required") :
-    LIBNSL_LIBS= ;; #(
+    libnsl="" ;; #(
   *) :
-    LIBNSL_LIBS=$ac_cv_search_yp_match
+    libnsl="$ac_cv_search_yp_match"
    ;;
 esac
+  LIBNSL_LIBS=${LIBNSL_LIBS-$libnsl}
 
 elif test $pkg_failed = untried; then
      	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
-  LIBNSL_CFLAGS=
+  LIBNSL_CFLAGS=${LIBNSL_CFLAGS-""}
   save_CFLAGS=$CFLAGS
 save_CPPFLAGS=$CPPFLAGS
 save_LDFLAGS=$LDFLAGS
@@ -11760,13 +11769,14 @@ LIBS=$save_LIBS
 
   case $ac_cv_search_yp_match in #(
   no) :
-    LIBNSL_LIBS= ;; #(
+    libnsl="" ;; #(
   "none required") :
-    LIBNSL_LIBS= ;; #(
+    libnsl="" ;; #(
   *) :
-    LIBNSL_LIBS=$ac_cv_search_yp_match
+    libnsl="$ac_cv_search_yp_match"
    ;;
 esac
+  LIBNSL_LIBS=${LIBNSL_LIBS-$libnsl}
 
 else
 	LIBNSL_CFLAGS=$pkg_cv_LIBNSL_CFLAGS
@@ -11867,16 +11877,16 @@ fi
 	echo "$LIBSQLITE3_PKG_ERRORS" >&5
 
 
-    LIBSQLITE3_LIBS="-lsqlite3"
-    LIBSQLITE3_CFLAGS=
+    LIBSQLITE3_CFLAGS=${LIBSQLITE3_CFLAGS-""}
+    LIBSQLITE3_LIBS=${LIBSQLITE3_LIBS-"-lsqlite3"}
 
 
 elif test $pkg_failed = untried; then
      	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
-    LIBSQLITE3_LIBS="-lsqlite3"
-    LIBSQLITE3_CFLAGS=
+    LIBSQLITE3_CFLAGS=${LIBSQLITE3_CFLAGS-""}
+    LIBSQLITE3_LIBS=${LIBSQLITE3_LIBS-"-lsqlite3"}
 
 
 else
@@ -12147,7 +12157,7 @@ $as_echo "$ac_cv_lib_gdbm_gdbm_open" >&6; }
 if test "x$ac_cv_lib_gdbm_gdbm_open" = xyes; then :
 
       have_gdbm=yes
-      GDBM_LIBS="$GDBM_LIBS -lgdbm"
+      GDBM_LIBS=${GDBM_LIBS-"-lgdbm"}
 
 else
   have_gdbm=no
@@ -14619,8 +14629,8 @@ $as_echo "$ac_cv_lib_z_gzread" >&6; }
 if test "x$ac_cv_lib_z_gzread" = xyes; then :
 
         have_zlib=yes
-        ZLIB_CFLAGS=
-        ZLIB_LIBS=-lz
+        ZLIB_CFLAGS=${ZLIB_CFLAGS-""}
+        ZLIB_LIBS=${ZLIB_LIBS-"-lz"}
         { $as_echo "$as_me:${as_lineno-$LINENO}: checking for inflateCopy in -lz" >&5
 $as_echo_n "checking for inflateCopy in -lz... " >&6; }
 if ${ac_cv_lib_z_inflateCopy+:} false; then :
@@ -14741,8 +14751,8 @@ $as_echo "$ac_cv_lib_z_gzread" >&6; }
 if test "x$ac_cv_lib_z_gzread" = xyes; then :
 
         have_zlib=yes
-        ZLIB_CFLAGS=
-        ZLIB_LIBS=-lz
+        ZLIB_CFLAGS=${ZLIB_CFLAGS-""}
+        ZLIB_LIBS=${ZLIB_LIBS-"-lz"}
         { $as_echo "$as_me:${as_lineno-$LINENO}: checking for inflateCopy in -lz" >&5
 $as_echo_n "checking for inflateCopy in -lz... " >&6; }
 if ${ac_cv_lib_z_inflateCopy+:} false; then :
@@ -14938,8 +14948,8 @@ $as_echo "$ac_cv_lib_bz2_BZ2_bzCompress" >&6; }
 if test "x$ac_cv_lib_bz2_BZ2_bzCompress" = xyes; then :
 
         have_bzip2=yes
-        BZIP2_CFLAGS=
-        BZIP2_LIBS=-lbz2
+        BZIP2_CFLAGS=${BZIP2_CFLAGS-""}
+        BZIP2_LIBS=${BZIP2_LIBS-"-lbz2"}
 
 else
   have_bzip2=no
@@ -15017,8 +15027,8 @@ $as_echo "$ac_cv_lib_bz2_BZ2_bzCompress" >&6; }
 if test "x$ac_cv_lib_bz2_BZ2_bzCompress" = xyes; then :
 
         have_bzip2=yes
-        BZIP2_CFLAGS=
-        BZIP2_LIBS=-lbz2
+        BZIP2_CFLAGS=${BZIP2_CFLAGS-""}
+        BZIP2_LIBS=${BZIP2_LIBS-"-lbz2"}
 
 else
   have_bzip2=no
@@ -15160,8 +15170,8 @@ $as_echo "$ac_cv_lib_lzma_lzma_easy_encoder" >&6; }
 if test "x$ac_cv_lib_lzma_lzma_easy_encoder" = xyes; then :
 
         have_liblzma=yes
-        LIBLZMA_CFLAGS=
-        LIBLZMA_LIBS=-llzma
+        LIBLZMA_CFLAGS=${LIBLZMA_CFLAGS-""}
+        LIBLZMA_LIBS=${LIBLZMA_LIBS-"-llzma"}
 
 else
   have_liblzma=no
@@ -15239,8 +15249,8 @@ $as_echo "$ac_cv_lib_lzma_lzma_easy_encoder" >&6; }
 if test "x$ac_cv_lib_lzma_lzma_easy_encoder" = xyes; then :
 
         have_liblzma=yes
-        LIBLZMA_CFLAGS=
-        LIBLZMA_LIBS=-llzma
+        LIBLZMA_CFLAGS=${LIBLZMA_CFLAGS-""}
+        LIBLZMA_LIBS=${LIBLZMA_LIBS-"-llzma"}
 
 else
   have_liblzma=no
@@ -15840,10 +15850,11 @@ if test "$ac_res" != no; then :
       $as_echo "#define HAVE_CRYPT_R 1" >>confdefs.h
 
       if test "$ac_cv_search_crypt_r" = "none required"; then
-        LIBCRYPT_LIBS=
+        libcrypt=
       else
-        LIBCRYPT_LIBS="$ac_cv_search_crypt_r"
+        libcrypt="$ac_cv_search_crypt_r"
       fi
+      LIBCRYPT_LIBS=${LIBCRYPT_LIBS-$libcrypt}
 
 fi
 
@@ -15922,10 +15933,11 @@ if test "$ac_res" != no; then :
       $as_echo "#define HAVE_CRYPT_R 1" >>confdefs.h
 
       if test "$ac_cv_search_crypt_r" = "none required"; then
-        LIBCRYPT_LIBS=
+        libcrypt=
       else
-        LIBCRYPT_LIBS="$ac_cv_search_crypt_r"
+        libcrypt="$ac_cv_search_crypt_r"
       fi
+      LIBCRYPT_LIBS=${LIBCRYPT_LIBS-$libcrypt}
 
 fi
 
diff --git a/configure.ac b/configure.ac
index 0905014..31544dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2947,8 +2947,8 @@ dnl stream in big-endian byte-order
 AC_CHECK_HEADERS([uuid.h], [
   AC_CHECK_FUNCS([uuid_create uuid_enc_be], [
     have_uuid=yes
-    LIBUUID_CFLAGS=
-    LIBUUID_LIBS=
+    LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+    LIBUUID_LIBS=${LIBUUID_LIBS-""}
   ])
 ])
 
@@ -2961,8 +2961,6 @@ AS_VAR_IF([have_uuid], [missing], [
       AC_DEFINE([HAVE_UUID_H], [1])
       AC_DEFINE([HAVE_UUID_GENERATE_TIME_SAFE], [1])
     ], [
-      LIBUUID_LIBS="-luuid"
-      LIBUUID_CFLAGS=
       AC_CHECK_HEADERS([uuid/uuid.h], [
         WITH_SAVE_ENV(
           [AC_CHECK_LIB([uuid], [uuid_generate_time], [have_uuid=yes])
@@ -2973,6 +2971,10 @@ AS_VAR_IF([have_uuid], [missing], [
             AC_DEFINE([HAVE_UUID_GENERATE_TIME_SAFE], [1])
           ])
         ])
+        AS_VAR_IF([have_uuid], [yes], [
+          LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+          LIBUUID_LIBS=${LIBUUID_LIBS-"-luuid"}
+        ])
       ])
     ]
   )
@@ -2983,8 +2985,8 @@ AS_VAR_IF([have_uuid], [missing], [
   AC_CHECK_HEADERS([uuid/uuid.h], [
     AC_CHECK_FUNC([uuid_generate_time], [
       have_uuid=yes
-      LIBUUID_CFLAGS=
-      LIBUUID_LIBS=
+      LIBUUID_CFLAGS=${LIBUUID_CFLAGS-""}
+      LIBUUID_LIBS=${LIBUUID_LIBS-""}
     ])
   ])
 ])
@@ -3147,8 +3149,8 @@ AC_ARG_WITH(system_expat,
 AC_MSG_RESULT($with_system_expat)
 
 AS_VAR_IF([with_system_expat], [yes], [
-  LIBEXPAT_CFLAGS=""
-  LIBEXPAT_LDFLAGS="-lexpat"
+  LIBEXPAT_CFLAGS=${LIBEXPAT_CFLAGS-""}
+  LIBEXPAT_LDFLAGS=${LIBEXPAT_LDFLAGS-"-lexpat"}
   LIBEXPAT_INTERNAL=
 ], [
   LIBEXPAT_CFLAGS="-I\$(srcdir)/Modules/expat"
@@ -3203,8 +3205,8 @@ AC_ARG_WITH(system_libmpdec,
 AC_MSG_RESULT($with_system_libmpdec)
 
 AS_VAR_IF([with_system_libmpdec], [yes], [
-  LIBMPDEC_CFLAGS=""
-  LIBMPDEC_LDFLAGS="-lmpdec"
+  LIBMPDEC_CFLAGS=${LIBMPDEC_CFLAGS-""}
+  LIBMPDEC_LDFLAGS=${LIBMPDEC_LDFLAGS-"-lmpdec"}
   LIBMPDEC_INTERNAL=
 ], [
   LIBMPDEC_CFLAGS="-I\$(srcdir)/Modules/_decimal/libmpdec"
@@ -3293,15 +3295,16 @@ fi
 dnl check for NIS / libnsl dependencies
 dnl libnsl dependencies include tirpc includes and lib
 PKG_CHECK_MODULES([LIBNSL], [libnsl], [have_nis=yes], [
-  LIBNSL_CFLAGS=
+  LIBNSL_CFLAGS=${LIBNSL_CFLAGS-""}
   WITH_SAVE_ENV([
     AC_SEARCH_LIBS([yp_match], [nsl], [have_nis=yes], [have_nis=no])
   ])
   AS_CASE([$ac_cv_search_yp_match],
-    [no], [LIBNSL_LIBS=],
-    ["none required"], [LIBNSL_LIBS=],
-    [LIBNSL_LIBS=$ac_cv_search_yp_match]
+    [no], [libnsl=""],
+    ["none required"], [libnsl=""],
+    [libnsl="$ac_cv_search_yp_match"]
   )
+  LIBNSL_LIBS=${LIBNSL_LIBS-$libnsl}
 ])
 
 AS_VAR_IF([have_nis], [yes], [
@@ -3314,8 +3317,8 @@ AS_VAR_IF([have_nis], [yes], [
 dnl Check for SQLite library. Use pkg-config if available.
 PKG_CHECK_MODULES(
   [LIBSQLITE3], [sqlite3 >= 3.7.15], [], [
-    LIBSQLITE3_LIBS="-lsqlite3"
-    LIBSQLITE3_CFLAGS=
+    LIBSQLITE3_CFLAGS=${LIBSQLITE3_CFLAGS-""}
+    LIBSQLITE3_LIBS=${LIBSQLITE3_LIBS-"-lsqlite3"}
   ]
 )
 AS_VAR_APPEND([LIBSQLITE3_CFLAGS], [' -I$(srcdir)/Modules/_sqlite'])
@@ -3402,7 +3405,7 @@ WITH_SAVE_ENV([
   AC_CHECK_HEADERS([gdbm.h], [
     AC_CHECK_LIB([gdbm], [gdbm_open], [
       have_gdbm=yes
-      GDBM_LIBS="$GDBM_LIBS -lgdbm"
+      GDBM_LIBS=${GDBM_LIBS-"-lgdbm"}
     ], [have_gdbm=no])
   ], [have_gdbm=no])
 ])
@@ -4196,8 +4199,8 @@ PKG_CHECK_MODULES([ZLIB], [zlib >= 1.2.0], [
     WITH_SAVE_ENV([
       AC_CHECK_LIB([z], [gzread], [
         have_zlib=yes
-        ZLIB_CFLAGS=
-        ZLIB_LIBS=-lz
+        ZLIB_CFLAGS=${ZLIB_CFLAGS-""}
+        ZLIB_LIBS=${ZLIB_LIBS-"-lz"}
         AC_CHECK_LIB([z], [inflateCopy], [AC_DEFINE([HAVE_ZLIB_COPY], [1])])
       ], [
         have_zlib=no
@@ -4217,8 +4220,8 @@ PKG_CHECK_MODULES([BZIP2], [bzip2], [have_bzip2=yes], [
     WITH_SAVE_ENV([
       AC_CHECK_LIB([bz2], [BZ2_bzCompress], [
         have_bzip2=yes
-        BZIP2_CFLAGS=
-        BZIP2_LIBS=-lbz2
+        BZIP2_CFLAGS=${BZIP2_CFLAGS-""}
+        BZIP2_LIBS=${BZIP2_LIBS-"-lbz2"}
       ], [have_bzip2=no])
     ])
   ], [have_bzip2=no])
@@ -4229,8 +4232,8 @@ PKG_CHECK_MODULES([LIBLZMA], [liblzma], [have_liblzma=yes], [
     WITH_SAVE_ENV([
       AC_CHECK_LIB([lzma], [lzma_easy_encoder], [
         have_liblzma=yes
-        LIBLZMA_CFLAGS=
-        LIBLZMA_LIBS=-llzma
+        LIBLZMA_CFLAGS=${LIBLZMA_CFLAGS-""}
+        LIBLZMA_LIBS=${LIBLZMA_LIBS-"-llzma"}
       ], [have_liblzma=no])
     ])
   ], [have_liblzma=no])
@@ -4303,10 +4306,11 @@ PKG_CHECK_MODULES([LIBCRYPT], [libxcrypt >= 3.1.1], [
     AC_SEARCH_LIBS([crypt_r], [crypt], [
       AC_DEFINE([HAVE_CRYPT_R], [1])
       if test "$ac_cv_search_crypt_r" = "none required"; then
-        LIBCRYPT_LIBS=
+        libcrypt=
       else
-        LIBCRYPT_LIBS="$ac_cv_search_crypt_r"
+        libcrypt="$ac_cv_search_crypt_r"
       fi
+      LIBCRYPT_LIBS=${LIBCRYPT_LIBS-$libcrypt}
     ])
   ])
 ])
diff --git a/setup.py b/setup.py
index 572f2ac..e30674f 100644
--- a/setup.py
+++ b/setup.py
@@ -665,7 +665,9 @@ class PyBuildExt(build_ext):
                 print("Custom linker flags may require --with-openssl-rpath=auto")
             print()
 
-        if os.environ.get("PYTHONSTRICTEXTENSIONBUILD") and (self.failed or self.failed_on_import):
+        if os.environ.get("PYTHONSTRICTEXTENSIONBUILD") and (
+            self.failed or self.failed_on_import or self.missing
+        ):
             raise RuntimeError("Failed to build some stdlib modules")
 
     def build_extension(self, ext):