meson: Fix generating static and both libraries under MSVC

Back when I implemented the mesonification of librsvg, I forced the
installable target of rsvg-2 to be a shared library. This was because
Meson and Rust, at link time, differ on the naming convention expected
of static libraries:

rust-lang/rust#122455

https://mesonbuild.com/FAQ.html#why-does-building-my-project-with-msvc-output-static-libraries-called-libfooa

I did not realise at the time that the fix merged in !938 (commit
73d7167) was not aware of this issue,
and so it broke the Cerbero builds targeting Microsoft compilers.
This commit works around the Rust bug by following the Linux convention for
static libraries, and then using a custom target to rename the Rust-generated
library if under MSVC.

All targets that depend on librsvg_lib do so now unconditionally, given
they must link at a time where the file outputs are settled.

Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/957>

gdk-pixbuf-loader/meson.build

@@ -10,6 +10,7 @@ pixbufloader = custom_target(
   console: true,
   install: true,
   install_dir: pixbuf_dep.get_variable(pkgconfig: 'gdk_pixbuf_moduledir'),
+  depends: librsvg_rust_dep,
   depend_files: pixbufloader_sources,
   env: extra_env,
   command: [
@@ -65,6 +66,6 @@ if build_tests.allowed()
       '--packages', 'pixbufloader-svg',
     ],
     env: extra_env,
-    depends: librsvg_lib
+    depends: pixbufloader
   )
 endif

meson.build

@@ -351,8 +351,7 @@ extra_env.set('PKG_CONFIG', pkg_config.full_path())
 
 pkg_config_path = get_option('pkg_config_path')
 if pkg_config_path.length() > 0
-  pathsep = build_machine.system() == 'windows' ? ';' : ':'
-  extra_env.set('PKG_CONFIG_PATH', pathsep.join(pkg_config_path))
+  extra_env.set('PKG_CONFIG_PATH', pkg_config_path)
 endif
 
 # Set up the environment that will be fed to the build
@@ -375,8 +374,8 @@ current_library_path = run_command(
 )
 
 extra_env.set(var, current_library_path.stdout().strip())
+extra_env.prepend(var, meson.project_build_root() / 'rsvg')
 if host_system == 'windows'
-  extra_env.prepend('PATH', meson.project_build_root() / 'rsvg')
   foreach i: library_dependencies_sole
     x = i.get_variable(pkgconfig: 'bindir', default_value: '')
     if x != ''
@@ -391,17 +390,10 @@ includeinc = include_directories('include')
 
 # Set the suffixes up
 if host_system == 'windows'
+  lib_prefix = is_msvc_style ? '' : 'lib'
   ext_dynamic = 'dll'
+  ext_static = is_msvc_style ? 'lib' : 'a'
   ext_exe = '.exe'
-  if is_msvc_style
-    lib_prefix = ''
-    ext_import = 'dll.lib'
-    ext_static = 'lib'
-  else
-    lib_prefix = 'lib'
-    ext_import = 'dll.a'
-    ext_static = 'a'
-  endif
 elif host_system == 'darwin'
   lib_prefix = 'lib'
   ext_dynamic = 'dylib'

rsvg/meson.build

@@ -214,8 +214,13 @@ else
   )
 endif
 
-if get_option('default_library') == 'shared'
-  librsvg_lib = shared_library(
+librsvg_lib = librsvg_c_lib
+
+# Wait on this dependency before trying to build using Rust
+librsvg_rust_dep = rust_artifacts
+
+if get_option('default_library') in ['shared', 'both']
+  librsvg_shared_lib = shared_library(
     rsvg_ver,
     rsvg_dummy,
     link_whole: librsvg_c_lib,
@@ -227,8 +232,30 @@ if get_option('default_library') == 'shared'
     install: true,
     version: meson.project_version() # it's not exact as m4
   )
-else
-  librsvg_lib = librsvg_c_lib
+  if get_option('default_library') == 'shared'
+    librsvg_lib = librsvg_shared_lib
+  endif
+  librsvg_rust_dep = librsvg_shared_lib
+endif
+if get_option('default_library') in ['static', 'both']
+  # Rust cannot yet use import libraries for MSVC which do not end in .lib.
+  # The static library must be manually generated so that it matches Meson's
+  # naming convention.
+  # See https://github.com/rust-lang/rust/issues/122455
+  librsvg_lib = custom_target(
+    'rsvg-2-static',
+    input: librsvg_c_lib,
+    output: '@0@rsvg-@1@.@2@'.format(lib_prefix, librsvg_api_major, 'a'),
+    command: [
+      python,
+      '-c',
+      'import os; import sys; import shutil; shutil.copy(sys.argv[1], sys.argv[2])',
+      '@INPUT0@',
+      '@OUTPUT0@'
+    ]
+  )
+
+  librsvg_rust_dep = librsvg_lib
 endif
 
 # This is the main dependency to use for tests; it means "link to the library we just built"
@@ -340,7 +367,7 @@ if build_tests.allowed()
       '--packages', 'librsvg',
     ] + avif_feature_args,
     env: extra_env,
-    depends: librsvg_lib
+    depends: librsvg_rust_dep
   )
 
   test(
@@ -356,6 +383,6 @@ if build_tests.allowed()
     ] + avif_feature_args
       + pixbuf_feature_args,
     env: extra_env,
-    depends: get_option('default_library') == 'shared' ? librsvg_lib : rust_artifacts
+    depends: librsvg_rust_dep
   )
 endif

rsvg_convert/meson.build

@@ -22,7 +22,7 @@ rsvg_convert = custom_target(
   console: true,
   install: true,
   install_dir: get_option('prefix') / get_option('bindir'),
-  depends: rust_artifacts,
+  depends: librsvg_rust_dep,
   depend_files: rsvg_convert_files,
   env: extra_env,
   command: [