From d6ddfe87e1e75fc26cb50e2e8be215443460d444 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Wed, 30 Nov 2022 02:18:38 +0100
Subject: [PATCH] Disable build system pkg-config when cross-compiling to
 non-Linux

This restores a modified form of the original commit 893ebbab0c (Disable
use of build system pkg-config files when cross-compiling, 2020-12-13),
thus mostly reverting 6dbf59f34f (Revert "Disable use of build system
pkg-config files when cross-compiling", 2022-10-25) and now disables the
use of build system pkg-config files only when cross-compiling for
non-Linux hosts.

This seems like the best behaviour by default because it avoids
unexpected problems when cross-compiling for MSW or iOS where build
system .pc files should never be used, but still uses these files, if
they are available, when cross-compiling for other Linux systems.

This is Linux-specific currently but should probably be extended to
other Unix systems too. In any case, the default behaviour can always be
overridden by setting PKG_CONFIG_LIBDIR manually.

See #22886.
---
 configure    | 20 ++++++++++++++++++++
 configure.in | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/configure b/configure
index f35f16bc12..0113ad1754 100755
--- a/configure
+++ b/configure
@@ -25051,6 +25051,26 @@ $as_echo "no" >&6; }
 
 fi
 
+if test "$build" != "$host"; then
+    case "${host}" in
+        *-linux-*)
+            ;;
+
+        *)
+            disable_build_system_pkg_config=1
+            ;;
+    esac
+fi
+
+if test "$disable_build_system_pkg_config" = 1; then
+
+
+                if test -z "$PKG_CONFIG_LIBDIR"; then
+        PKG_CONFIG_LIBDIR=/dev/null
+        export PKG_CONFIG_LIBDIR
+    fi
+fi
+
 
 
 if test "$wxUSE_REGEX" != "no"; then
diff --git a/configure.in b/configure.in
index 5e3a8cd147..e5daa36694 100644
--- a/configure.in
+++ b/configure.in
@@ -2093,6 +2093,39 @@ fi
 dnl Find pkg-config outside of any conditional.  Done before any PKG_* call.
 PKG_PROG_PKG_CONFIG
 
+dnl When cross-compiling for another system from Linux, don't use .pc files on
+dnl the build system, they are at best useless and can be harmful (e.g. they
+dnl may define options inappropriate for the cross-build, resulting in the
+dnl failure of all the subsequent tests).
+dnl
+dnl Note that we only do it in this particular case because in other cases we
+dnl may want to use .pc files on the build system, e.g. it's common to have
+dnl them when cross-compiling from x86_64 Linux to ARM Linux.
+if test "$build" != "$host"; then
+    case "${host}" in
+        *-linux-*)
+            ;;
+
+        *)
+            disable_build_system_pkg_config=1
+            ;;
+    esac
+fi
+
+if test "$disable_build_system_pkg_config" = 1; then
+    dnl pkg.m4 forbids the use of PKG_XXX, so undo it here to avoid autoconf
+    dnl errors.
+    m4_pattern_allow([PKG_CONFIG_LIBDIR])
+
+    dnl If pkg-config libdir is already defined, we suppose that they know what
+    dnl they're doing and leave it alone, but if not, set it to a path in which
+    dnl no .pc files will be found.
+    if test -z "$PKG_CONFIG_LIBDIR"; then
+        PKG_CONFIG_LIBDIR=/dev/null
+        export PKG_CONFIG_LIBDIR
+    fi
+fi
+
 dnl ---------------------------------------------------------------------------
 dnl Optional libraries
 dnl