bpo-45723: Add --with-pkg-config to configure (GH-29517)

Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>

4 files changed, 210 insertions, 135 deletions

diff --git a/Doc/using/configure.rst b/Doc/using/configure.rst
index 75f572c..f00766d 100644
--- a/Doc/using/configure.rst
+++ b/Doc/using/configure.rst
@@ -116,6 +116,17 @@ General Options
 
    .. versionadded:: 3.10
 
+.. cmdoption:: --with-pkg-config=[check|yes|no]
+
+   Whether configure should use :program:`pkg-config` to detect build
+   dependencies.
+
+   * ``check`` (default): :program:`pkg-config` is optional
+   * ``yes``: :program:`pkg-config` is mandatory
+   * ``no``: configure does not use :program:`pkg-config` even when present
+
+   .. versionadded:: 3.11
+
 
 Install Options
 ---------------
diff --git a/Misc/NEWS.d/next/Build/2021-11-10-16-13-02.bpo-45723.B5gCB1.rst b/Misc/NEWS.d/next/Build/2021-11-10-16-13-02.bpo-45723.B5gCB1.rst
new file mode 100644
index 0000000..4963618
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-11-10-16-13-02.bpo-45723.B5gCB1.rst
@@ -0,0 +1,2 @@
+:program:`configure` has a new option ``--with-pkg-config`` to disable or
+require pkg-config.
diff --git a/configure b/configure
index 2a89703..3c5a5da 100755
--- a/configure
+++ b/configure
@@ -661,9 +661,6 @@ DTRACE
 TCLTK_LIBS
 TCLTK_INCLUDES
 LIBFFI_INCLUDEDIR
-PKG_CONFIG_LIBDIR
-PKG_CONFIG_PATH
-PKG_CONFIG
 TZPATH
 SHLIBS
 CFLAGSFORSHARED
@@ -756,6 +753,9 @@ LIPO_INTEL64_FLAGS
 LIPO_32BIT_FLAGS
 ARCH_RUN_32BIT
 UNIVERSALSDK
+PKG_CONFIG_LIBDIR
+PKG_CONFIG_PATH
+PKG_CONFIG
 CONFIG_ARGS
 SOVERSION
 VERSION
@@ -816,6 +816,7 @@ SHELL'
 ac_subst_files=''
 ac_user_opts='
 enable_option_checking
+with_pkg_config
 enable_universalsdk
 with_universal_archs
 with_framework_name
@@ -869,6 +870,9 @@ enable_test_modules
       ac_precious_vars='build_alias
 host_alias
 target_alias
+PKG_CONFIG
+PKG_CONFIG_PATH
+PKG_CONFIG_LIBDIR
 MACHDEP
 CC
 CFLAGS
@@ -876,10 +880,7 @@ LDFLAGS
 LIBS
 CPPFLAGS
 CPP
-PROFILE_TASK
-PKG_CONFIG
-PKG_CONFIG_PATH
-PKG_CONFIG_LIBDIR'
+PROFILE_TASK'
 
 
 # Initialize some variables set by options.
@@ -1532,6 +1533,8 @@ Optional Features:
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
   --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
+  --with-pkg-config       use pkg-config to detect build options (default is
+                          check)
   --with-universal-archs=ARCH
                           specify the kind of macOS universal binary that
                           should be created. This option is only valid when
@@ -1634,6 +1637,11 @@ Optional Packages:
                           install python.o (default is yes)
 
 Some influential environment variables:
+  PKG_CONFIG  path to pkg-config utility
+  PKG_CONFIG_PATH
+              directories to add to pkg-config's search path
+  PKG_CONFIG_LIBDIR
+              path overriding pkg-config's built-in search path
   MACHDEP     name for machine-dependent library files
   CC          C compiler command
   CFLAGS      C compiler flags
@@ -1645,11 +1653,6 @@ Some influential environment variables:
   CPP         C preprocessor
   PROFILE_TASK
               Python args for PGO generation task
-  PKG_CONFIG  path to pkg-config utility
-  PKG_CONFIG_PATH
-              directories to add to pkg-config's search path
-  PKG_CONFIG_LIBDIR
-              path overriding pkg-config's built-in search path
 
 Use these variables to override the choices made by `configure' or to help
 it to find libraries and programs with nonstandard names/locations.
@@ -3079,6 +3082,158 @@ define_xopen_source=yes
 
 CONFIG_ARGS="$ac_configure_args"
 
+
+# Check whether --with-pkg-config was given.
+if test "${with_pkg_config+set}" = set; then :
+  withval=$with_pkg_config;
+else
+  with_pkg_config=check
+
+fi
+
+case $with_pkg_config in #(
+  yes|check) :
+
+    if test -z "$PKG_CONFIG"; then
+            { PKG_CONFIG=; unset PKG_CONFIG;}
+      { ac_cv_path_ac_pt_PKG_CONFIG=; unset ac_cv_path_ac_pt_PKG_CONFIG;}
+      { ac_cv_prog_ac_ct_PKG_CONFIG=; unset ac_cv_prog_ac_ct_PKG_CONFIG;}
+    fi
+
+
+
+
+
+
+
+if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
+	if test -n "$ac_tool_prefix"; then
+  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
+set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_PKG_CONFIG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $PKG_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac
+fi
+PKG_CONFIG=$ac_cv_path_PKG_CONFIG
+if test -n "$PKG_CONFIG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
+$as_echo "$PKG_CONFIG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+fi
+if test -z "$ac_cv_path_PKG_CONFIG"; then
+  ac_pt_PKG_CONFIG=$PKG_CONFIG
+  # Extract the first word of "pkg-config", so it can be a program name with args.
+set dummy pkg-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $ac_pt_PKG_CONFIG in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  ;;
+esac
+fi
+ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
+if test -n "$ac_pt_PKG_CONFIG"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
+$as_echo "$ac_pt_PKG_CONFIG" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+  if test "x$ac_pt_PKG_CONFIG" = x; then
+    PKG_CONFIG=""
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    PKG_CONFIG=$ac_pt_PKG_CONFIG
+  fi
+else
+  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
+fi
+
+fi
+if test -n "$PKG_CONFIG"; then
+	_pkg_min_version=0.9.0
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
+$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
+	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+	else
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+		PKG_CONFIG=""
+	fi
+fi
+   ;; #(
+  no) :
+
+    PKG_CONFIG=''
+        ac_cv_path_ac_pt_PKG_CONFIG=''
+    ac_cv_prog_ac_ct_PKG_CONFIG=''
+   ;; #(
+  *) :
+    as_fn_error $? "invalid argument --with-pkg-config=$with_pkg_config" "$LINENO" 5
+ ;;
+esac
+if test "$with_pkg_config" = yes -a -z "$PKG_CONFIG"; then
+  as_fn_error $? "pkg-config is required" "$LINENO" 5]
+fi
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --enable-universalsdk" >&5
 $as_echo_n "checking for --enable-universalsdk... " >&6; }
 # Check whether --enable-universalsdk was given.
@@ -10541,127 +10696,6 @@ $as_echo "no" >&6; }
 fi
 
 
-
-
-
-
-
-
-
-if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
-	if test -n "$ac_tool_prefix"; then
-  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
-set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_path_PKG_CONFIG+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  case $PKG_CONFIG in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac
-fi
-PKG_CONFIG=$ac_cv_path_PKG_CONFIG
-if test -n "$PKG_CONFIG"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
-$as_echo "$PKG_CONFIG" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
-fi
-if test -z "$ac_cv_path_PKG_CONFIG"; then
-  ac_pt_PKG_CONFIG=$PKG_CONFIG
-  # Extract the first word of "pkg-config", so it can be a program name with args.
-set dummy pkg-config; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  case $ac_pt_PKG_CONFIG in
-  [\\/]* | ?:[\\/]*)
-  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
-  ;;
-  *)
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
-  IFS=$as_save_IFS
-  test -z "$as_dir" && as_dir=.
-    for ac_exec_ext in '' $ac_executable_extensions; do
-  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
-    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
-    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
-    break 2
-  fi
-done
-  done
-IFS=$as_save_IFS
-
-  ;;
-esac
-fi
-ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
-if test -n "$ac_pt_PKG_CONFIG"; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
-$as_echo "$ac_pt_PKG_CONFIG" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-  if test "x$ac_pt_PKG_CONFIG" = x; then
-    PKG_CONFIG=""
-  else
-    case $cross_compiling:$ac_tool_warned in
-yes:)
-{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
-    PKG_CONFIG=$ac_pt_PKG_CONFIG
-  fi
-else
-  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
-fi
-
-fi
-if test -n "$PKG_CONFIG"; then
-	_pkg_min_version=0.9.0
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
-$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
-	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-	else
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-		PKG_CONFIG=""
-	fi
-fi
-
 # Check for use of the system expat library
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-system-expat" >&5
 $as_echo_n "checking for --with-system-expat... " >&6; }
diff --git a/configure.ac b/configure.ac
index 4817422..898c2ba 100644
--- a/configure.ac
+++ b/configure.ac
@@ -155,6 +155,36 @@ define_xopen_source=yes
 AC_SUBST(CONFIG_ARGS)
 CONFIG_ARGS="$ac_configure_args"
 
+dnl Allow users to disable pkg-config or require pkg-config
+AC_ARG_WITH(
+  [pkg-config],
+  [AS_HELP_STRING([[--with-pkg-config=[yes|no|check]]],
+                  [use pkg-config to detect build options (default is check)])],
+  [],
+  [with_pkg_config=check]
+)
+AS_CASE([$with_pkg_config],
+  [yes|check], [
+    if test -z "$PKG_CONFIG"; then
+      dnl invalidate stale config.cache values
+      AS_UNSET([PKG_CONFIG])
+      AS_UNSET([ac_cv_path_ac_pt_PKG_CONFIG])
+      AS_UNSET([ac_cv_prog_ac_ct_PKG_CONFIG])
+    fi
+    PKG_PROG_PKG_CONFIG
+  ],
+  [no], [
+    PKG_CONFIG=''
+    dnl force AX_CHECK_OPENSSL to ignore pkg-config
+    ac_cv_path_ac_pt_PKG_CONFIG=''
+    ac_cv_prog_ac_ct_PKG_CONFIG=''
+  ],
+  [AC_MSG_ERROR([invalid argument --with-pkg-config=$with_pkg_config])]
+)
+if test "$with_pkg_config" = yes -a -z "$PKG_CONFIG"; then
+  AC_MSG_ERROR([pkg-config is required])]
+fi
+
 AC_MSG_CHECKING([for --enable-universalsdk])
 AC_ARG_ENABLE(universalsdk,
 	AS_HELP_STRING([--enable-universalsdk@<:@=SDKDIR@:>@],
@@ -2978,8 +3008,6 @@ LIBS="$withval $LIBS"
 ],
 [AC_MSG_RESULT(no)])
 
-PKG_PROG_PKG_CONFIG
-
 # Check for use of the system expat library
 AC_MSG_CHECKING(for --with-system-expat)
 AC_ARG_WITH(system_expat,