pkgconfig: Add a simple version of the generator (#3284)

docs/markdown/Pkgconfig-module.md

@@ -51,3 +51,10 @@ keyword arguments.
 - `version` a string describing the version of this library
 - `d_module_versions` a list of module version flags used when compiling
    D sources referred to by this pkg-config file
+
+Since 0.46 a `StaticLibrary` or `SharedLibrary` object can optionally be passed
+as first positional argument. If one is provided a default value will be
+provided for all required fields of the pc file:
+- `install_dir` is set to `pkgconfig` folder in the same location than the provided library.
+- `description` is set to the project's name followed by the library's name.
+- `name` is set to the library's name.

docs/markdown/snippets/pkgconfig-generator.md

@@ -0,0 +1,14 @@
+## Improvements to pkgconfig module
+
+A `StaticLibrary` or `SharedLibrary` object can optionally be passed
+as first positional argument of the `generate()` method. If one is provided a
+default value will be provided for all required fields of the pc file:
+- `install_dir` is set to `pkgconfig` folder in the same location than the provided library.
+- `description` is set to the project's name followed by the library's name.
+- `name` is set to the library's name.
+
+Generating a .pc file is now as simple as:
+
+```
+pkgconfig.generate(mylib)
+```

mesonbuild/modules/pkgconfig.py

@@ -301,20 +301,34 @@ class PkgConfigModule(ExtensionModule):
                       'subdirs', 'requires', 'requires_private', 'libraries_private',
                       'install_dir', 'extra_cflags', 'variables', 'url', 'd_module_versions'})
     def generate(self, state, args, kwargs):
-        if len(args) > 0:
-            raise mesonlib.MesonException('Pkgconfig_gen takes no positional arguments.')
+        default_version = state.project_version['version']
+        default_install_dir = None
+        default_description = None
+        default_name = None
+        mainlib = None
+        if len(args) == 1:
+            mainlib = getattr(args[0], 'held_object', args[0])
+            if not isinstance(mainlib, (build.StaticLibrary, build.SharedLibrary)):
+                raise mesonlib.MesonException('Pkgconfig_gen first positional argument must be a library object')
+            default_name = mainlib.name
+            default_description = state.project_name + ': ' + mainlib.name
+            install_dir = mainlib.get_custom_install_dir()[0]
+            if isinstance(install_dir, str):
+                default_install_dir = os.path.join(install_dir, 'pkgconfig')
+        elif len(args) > 1:
+            raise mesonlib.MesonException('Too many positional arguments passed to Pkgconfig_gen.')
 
         subdirs = mesonlib.stringlistify(kwargs.get('subdirs', ['.']))
-        version = kwargs.get('version', None)
+        version = kwargs.get('version', default_version)
         if not isinstance(version, str):
             raise mesonlib.MesonException('Version must be specified.')
-        name = kwargs.get('name', None)
+        name = kwargs.get('name', default_name)
         if not isinstance(name, str):
             raise mesonlib.MesonException('Name not specified.')
         filebase = kwargs.get('filebase', name)
         if not isinstance(filebase, str):
             raise mesonlib.MesonException('Filebase must be a string.')
-        description = kwargs.get('description', None)
+        description = kwargs.get('description', default_description)
         if not isinstance(description, str):
             raise mesonlib.MesonException('Description is not a string.')
         url = kwargs.get('url', '')
@@ -323,6 +337,8 @@ class PkgConfigModule(ExtensionModule):
         conflicts = mesonlib.stringlistify(kwargs.get('conflicts', []))
 
         deps = DependenciesHelper(filebase)
+        if mainlib:
+            deps.add_pub_libs(mainlib)
         deps.add_pub_libs(kwargs.get('libraries', []))
         deps.add_priv_libs(kwargs.get('libraries_private', []))
         deps.add_pub_reqs(kwargs.get('requires', []))
@@ -362,7 +378,7 @@ class PkgConfigModule(ExtensionModule):
         variables = parse_variable_list(mesonlib.stringlistify(kwargs.get('variables', [])))
 
         pcfile = filebase + '.pc'
-        pkgroot = kwargs.get('install_dir', None)
+        pkgroot = kwargs.get('install_dir', default_install_dir)
         if pkgroot is None:
             pkgroot = os.path.join(state.environment.coredata.get_builtin_option('libdir'), 'pkgconfig')
         if not isinstance(pkgroot, str):

test cases/common/51 pkgconfig-gen/dependencies/meson.build

@@ -1,4 +1,4 @@
-project('pkgconfig-gen-dependencies', 'c')
+project('pkgconfig-gen-dependencies', 'c', version: '1.0')
 
 pkgg = import('pkgconfig')
 
@@ -7,11 +7,7 @@ exposed_lib = shared_library('libexposed', 'exposed.c')
 internal_lib = shared_library('libinternal', 'internal.c')
 main_lib = static_library('libmain', link_with : [exposed_lib, internal_lib])
 
-pkgg.generate(libraries : exposed_lib,
-  version : '1.0',
-  name : 'libexposed',
-  description : 'An exposed library in dependency test.'
-)
+pkgg.generate(exposed_lib)
 
 # Declare a few different Dependency objects
 pc_dep = dependency('libfoo', version : '>=1.0')