[gjs/meson.msvc] installed-tests/js/meson.build: Fix building test DLLs

[Chun-wei Fan <fanchunwei src gnome org>]

commit badbfa02ba34d6accf072a5ecc315582226b350b
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Oct 25 17:17:11 2019 +0800

    installed-tests/js/meson.build: Fix building test DLLs
    
    The test DLLs, in which the sources are provided by
    GObject-Introspection, need to be built with _GI_EXTERN properly
    overridden on MSVC builds so that the symbols in those test DLLs are
    exported properly, so that we can build the introspection files for them
    properly when building the minijasmine test program.

 installed-tests/js/meson.build | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
---
diff --git a/installed-tests/js/meson.build b/installed-tests/js/meson.build
index 0d4ba3de..c4a4150b 100644
--- a/installed-tests/js/meson.build
+++ b/installed-tests/js/meson.build
@@ -15,6 +15,13 @@ minijasmine = executable('minijasmine', '../minijasmine.cpp',
 gidatadir = gi.get_pkgconfig_variable('gidatadir')
 gi_tests = gidatadir / 'tests'
 
+test_gir_extra_cpp_args = []
+
+# We need to ensure the symbols in the test DLLs export in MSVC builds
+if cxx.get_id() == 'msvc'
+  test_gir_extra_cpp_args += ['-D_GI_EXTERN=__declspec(dllexport)extern']
+endif
+
 regress_dependencies = [glib, gobject, gio]
 regress_gir_includes = ['Gio-2.0']
 regress_gir_cpp_args = []
@@ -29,7 +36,9 @@ regress_sources = [
     gi_tests / 'regress.c',
     gi_tests / 'regress.h',
 ]
-libregress = library('regress', regress_sources, cpp_args: regress_gir_cpp_args,
+libregress = library('regress', regress_sources,
+    c_args: test_gir_extra_cpp_args,
+    cpp_args: regress_gir_cpp_args,
     dependencies: regress_dependencies, install: get_option('installed_tests'),
     install_dir: pkglibdir)
 regress_gir = gnome.generate_gir(libregress, includes: regress_gir_includes,
@@ -45,6 +54,7 @@ warnlib_sources = [
     gi_tests / 'warnlib.h',
 ]
 libwarnlib = library('warnlib', warnlib_sources,
+    c_args:  test_gir_extra_cpp_args,
     dependencies: [glib, gobject, gio])
 # This should have --warn-all turned off, but there is currently no way to do so
 # in gnome.generate_gir(). See https://github.com/mesonbuild/meson/issues/5876
@@ -61,6 +71,7 @@ gimarshallingtests_sources = [
 ]
 libgimarshallingtests = library('gimarshallingtests',
     gimarshallingtests_sources, dependencies: [glib, gobject, gio],
+    c_args:  test_gir_extra_cpp_args,
     install: get_option('installed_tests'), install_dir: pkglibdir)
 gimarshallingtests_gir = gnome.generate_gir(libgimarshallingtests,
     includes: ['Gio-2.0'], sources: gimarshallingtests_sources,