[gimp] meson: fix glib-networking check when cross-compiling.

[Jehan <jehanp src gnome org>]

commit b8c34c41f14015ead639fdeaa77aef1738144c1e
Author: Jehan <jehan girinstud io>
Date:   Sat Sep 21 12:22:57 2019 +0200

    meson: fix glib-networking check when cross-compiling.
    
    3 cases are possible:
    - in native build, the test must succeed and is a fatale error.
    - in cross-compilation, if no `exe_wrapper` binaries were set in the
      toolchain file, we just bypass the check, yet still output a warning
      so that packagers won't forget to add the dependency.
    - in cross-compilation with an `exe_wrapper` (for instance `wine` for a
      win32 target), we run the check. Even if it fails, we don't make it a
      fatale error then simply output a warning as cross-platform execution
      are not always reliable anyway.

 meson.build | 53 +++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 37 insertions(+), 16 deletions(-)
---
diff --git a/meson.build b/meson.build
index 7b04107024..af02771a29 100644
--- a/meson.build
+++ b/meson.build
@@ -355,20 +355,14 @@ conf.set('PANGO_DISABLE_DEPRECATED',pangocairo.version().version_compare('<1.43'
 ################################################################################
 # Check for GLib Networking
 
-glib_networking_works_run = cc.run(
-  '''#include <gio/gio.h>
-  int main() {
-    return !g_tls_backend_supports_tls (g_tls_backend_get_default ());
-  }''',
-  dependencies: gio,
-)
-glib_networking_works =(glib_networking_works_run.compiled()
-                    and glib_networking_works_run.returncode() == 0)
-
-if not glib_networking_works
-  if meson.is_cross_build()
+glib_networking_works_run=false
+if meson.is_cross_build() and not meson.has_exe_wrapper()
+    # Cross-compilation without run capability: we won't be able to
+    # check networking support.
+    glib_networking_works = true
     glib_warning = '''
-      Test for glib-networking cannot be performed while cross-compiling.
+      Test for glib-networking cannot be performed while cross-compiling,
+      unless you set an `exe_wrapper` binary in your toolchain file.
       Make sure glib-networking is installed, otherwise GIMP will not be able
       to display the remote help pages through the help browser, nor will it
       be able to open remote HTTPS (or other protocol using SSL/TLS) files.
@@ -377,9 +371,36 @@ if not glib_networking_works
     '''
     warning(glib_warning)
     warnings += glib_warning
-  else
-    error('Test for glib-networking failed. This is required.')
-  endif
+else # not meson.is_cross_build() or meson.has_exe_wrapper()
+    glib_networking_works_run = cc.run(
+      '''#include <gio/gio.h>
+      int main() {
+        return !g_tls_backend_supports_tls (g_tls_backend_get_default ());
+      }''',
+      dependencies: gio,
+    )
+    glib_networking_works = (glib_networking_works_run.compiled() and
+                             glib_networking_works_run.returncode() == 0)
+    if not glib_networking_works and meson.is_cross_build()
+        # Since cross-platform test runs may be unreliable, let's be
+        # flexible and pass the test with a warning.
+        glib_networking_works = true
+        glib_warning = '''
+      The cross-platform test for glib-networking failed, using the
+      `exe_wrapper` set in your toolchain file.
+      Make sure glib-networking is installed, otherwise GIMP will not be able
+      to display the remote help pages through the help browser, nor will it
+      be able to open remote HTTPS (or other protocol using SSL/TLS) files.
+      HTTPS is becoming the expected standard and should not be considered
+      optional anymore.
+        '''
+        warning(glib_warning)
+        warnings += glib_warning
+    endif
+endif
+
+if not glib_networking_works
+  error('Test for glib-networking failed. This is required.')
 endif
 
 ################################################################################