Allow vs_module_defs to use a custom_target

Allow vs_module_defs to use a custom_target
Add a test and update documentation

docs/markdown/Reference-manual.md

@@ -582,7 +582,7 @@ Builds a shared library with the given sources. Positional and keyword arguments
 
 - `version` a string specifying the version of this shared library, such as `1.1.0`. On Linux and OS X, this is used to set the shared library version in the filename, such as `libfoo.so.1.1.0` and `libfoo.1.1.0.dylib`. If this is not specified, `soversion` is used instead (see below).
 - `soversion` a string specifying the soversion of this shared library, such as `0`. On Linux and Windows this is used to set the soversion (or equivalent) in the filename. For example, if `soversion` is `4`, a Windows DLL will be called `foo-4.dll` and one of the aliases of the Linux shared library would be `libfoo.so.4`. If this is not specified, the first part of `version` is used instead. For example, if `version` is `3.6.0` and `soversion` is not defined, it is set to `3`.
-- `vs_module_defs` a string pointing to a file or a File object that is a Microsoft module definition file for controlling symbol exports, etc., on platforms where that is possible (e.g. Windows).
+- `vs_module_defs` a string, a File object, or Custom Target for a Microsoft module definition file for controlling symbol exports, etc., on platforms where that is possible (e.g. Windows).
 
 ### shared_module()
 

mesonbuild/build.py

@@ -1281,6 +1281,8 @@ class SharedLibrary(BuildTarget):
         # Visual Studio module-definitions file
         if 'vs_module_defs' in kwargs:
             path = kwargs['vs_module_defs']
+            if hasattr(path, 'held_object'):
+                path = path.held_object
             if isinstance(path, str):
                 if os.path.isabs(path):
                     self.vs_module_defs = File.from_absolute_file(path)
@@ -1291,10 +1293,15 @@ class SharedLibrary(BuildTarget):
                 # When passing a generated file.
                 self.vs_module_defs = path
                 self.link_depends.append(path)
+            elif hasattr(path, 'get_filename'):
+                # When passing output of a Custom Target
+                path = File.from_built_file(path.subdir, path.get_filename())
+                self.vs_module_defs = path
+                self.link_depends.append(path)
             else:
                 raise InvalidArguments(
                     'Shared library vs_module_defs must be either a string, '
-                    'or a file object')
+                    'a file object or a Custom Target')
 
     def check_unknown_kwargs(self, kwargs):
         self.check_unknown_kwargs_int(kwargs, known_lib_kwargs)

test cases/windows/11 vs module defs generated custom target/meson.build

@@ -0,0 +1,10 @@
+project('generated_dll_module_defs', 'c')
+
+if meson.backend().startswith('vs')
+  # FIXME: Broken on the VS backends
+  error('MESON_SKIP_TEST see https://github.com/mesonbuild/meson/issues/1799')
+endif
+
+subdir('subdir')
+exe = executable('prog', 'prog.c', link_with : shlib)
+test('runtest', exe)

test cases/windows/11 vs module defs generated custom target/prog.c

@@ -0,0 +1,5 @@
+int somedllfunc();
+
+int main(int argc, char **argv) {
+    return somedllfunc() == 42 ? 0 : 1;
+}

test cases/windows/11 vs module defs generated custom target/subdir/make_def.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+import sys
+
+with open(sys.argv[1], 'w') as f:
+    print('EXPORTS', file=f)
+    print('        somedllfunc', file=f)

test cases/windows/11 vs module defs generated custom target/subdir/meson.build

@@ -0,0 +1,7 @@
+make_def = find_program('make_def.py')
+
+def_file = custom_target('gen_def',
+        command: [make_def, '@OUTPUT@'],
+        output: 'somedll.def')
+
+shlib = shared_library('somedll', 'somedll.c', vs_module_defs: def_file)

test cases/windows/11 vs module defs generated custom target/subdir/somedll.c

@@ -0,0 +1,3 @@
+int somedllfunc() {
+    return 42;
+}