[gtkmm/use-dllexport-3-24-meson: 18/21] Meson: Fix linking demos and tests on Visual Studio

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

commit 0de82e0febacac30b44fd0fd59e105564c6ba718
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed May 13 17:08:25 2020 +0800

    Meson: Fix linking demos and tests on Visual Studio
    
    GTK (and therefore gtkmm) applications require a linker flag
    '-entry:mainCRTStartup' if building with 'gui_app' is set to be true (which
    means, we are using /subsystem:windows in the linker flags on Visual Studio)
    unless a WinMain() is defined in the individual application's sources.
    
    This fixes the build of such programs by adding this linker flag where it is
    needed.

 demos/gtk-demo/meson.build | 3 ++-
 meson.build                | 9 ++++++++-
 tests/meson.build          | 3 ++-
 3 files changed, 12 insertions(+), 3 deletions(-)
---
diff --git a/demos/gtk-demo/meson.build b/demos/gtk-demo/meson.build
index b80b3069..3faf21a0 100644
--- a/demos/gtk-demo/meson.build
+++ b/demos/gtk-demo/meson.build
@@ -1,6 +1,6 @@
 # demos/gtk-demo
 
-# Input: gtkmm_dep, epoxy_dep, build_demos
+# Input: gtkmm_dep, epoxy_dep, build_demos, gui_app_ldflags
 # Output: -
 
 gtkmm_demo_cc_files = [
@@ -49,6 +49,7 @@ if epoxy_dep.found()
     dependencies: [gtkmm_dep, epoxy_dep],
     gui_app: true,
     build_by_default: build_demos,
+    link_args: gui_app_ldflags,
     install: false,
   )
 endif
diff --git a/meson.build b/meson.build
index b80d1271..e6d9b9f8 100644
--- a/meson.build
+++ b/meson.build
@@ -278,13 +278,20 @@ endif
 warning_flags = cpp_compiler.get_supported_arguments(warning_flags)
 add_project_arguments(warning_flags, language: 'cpp')
 
+gui_app_ldflags = []
+
 # MSVC: Ignore warnings that aren't really harmful, but make those
-#       that should not be overlooked stand out.
+#       that should not be overlooked stand out.  For gtkmm applications
+#       where we do not want a console window to show up with Visual Studio
+#       builds, we must use '-entry:mainCRTStartup' in the linker flags,
+#       otherwise the program will fail to link unless we defined a WinMain()
+#       for them
 if is_msvc
   foreach wd : ['/FImsvc_recommended_pragmas.h', '/wd4267', '/wd4530', '/wd4250', '/wd4251', '/wd4273', 
'/wd4275', '/wd4805']
     disabled_warning = cpp_compiler.get_supported_arguments(wd)
     add_project_arguments(disabled_warning, language: 'cpp')
   endforeach
+  gui_app_ldflags += '-entry:mainCRTStartup'
 endif
 
 subdir('tools/extra_defs_gen')
diff --git a/tests/meson.build b/tests/meson.build
index 07411a27..23f9c32c 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -1,6 +1,6 @@
 # tests
 
-# Input: gdkmm_dep, gtkmm_dep, build_tests
+# Input: gdkmm_dep, gtkmm_dep, build_tests, gui_app_ldflags
 # Output: -
 
 test_programs = [
@@ -37,6 +37,7 @@ foreach ex : test_programs
     dependencies: ex[3] ? gtkmm_dep : gdkmm_dep,
     gui_app: ex[3],
     build_by_default: build_tests,
+    link_args: ex[3] ? gui_app_ldflags : [],
     install: false,
   )