pkgconfig: Generate -uninstalled.pc files

Closes: mesonbuild#3472.

docs/markdown/Pkgconfig-module.md

@@ -51,10 +51,19 @@ 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
+- `uninstalled_variables` used instead of the `variables` keyword argument, when
+  generating the uninstalled pkg-config file. Since *0.49.0*
 
 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.
+
+Since 0.49.0 uninstalled pkg-config files are generated as well. They are
+located in `<build dir>/pkgconfig-uninstalled/*-uninstalled.pc`. It is useful to
+build projects against libraries built by meson without having to install them
+into a prefix. In order to do so, just set `PKG_CONFIG_PATH=<builddir>/pkgconfig-uninstalled`
+before building your application. That will cause pkg-config to use those pc files
+in priority and find libraries and headers from the meson builddir.

docs/markdown/snippets/uninstalled-pkgconfig.md

@@ -0,0 +1,7 @@
+## Uninstalled pkg-config files
+
+The `pkgconfig` module now generates uninstalled pc files as well. For any generated
+`foo.pc` file, an extra `foo-uninstalled.pc` file is placed into
+`<builddir>/pkgconfig-uninstalled`. They can be used to build applications against
+libraries built by meson without installing them, by pointing `PKG_CONFIG_PATH`
+to that directory.

mesonbuild/modules/pkgconfig.py

@@ -231,19 +231,30 @@ def _make_relative(self, prefix, subdir):
         return subdir
 
     def generate_pkgconfig_file(self, state, deps, subdirs, name, description,
-                                url, version, pcfile, conflicts, variables):
+                                url, version, pcfile, conflicts, variables,
+                                uninstalled=False):
         deps.remove_dups()
         coredata = state.environment.get_coredata()
-        outdir = state.environment.scratch_dir
-        fname = os.path.join(outdir, pcfile)
-        prefix = PurePath(coredata.get_builtin_option('prefix'))
-        # These always return paths relative to prefix
-        libdir = PurePath(coredata.get_builtin_option('libdir'))
-        incdir = PurePath(coredata.get_builtin_option('includedir'))
+        if not uninstalled:
+            fname = os.path.join(state.environment.scratch_dir, pcfile)
+        else:
+            outdir = os.path.join(state.environment.build_dir, 'pkgconfig-uninstalled')
+            if not os.path.exists(outdir):
+                os.mkdir(outdir)
+            fname = os.path.join(outdir, pcfile)
         with open(fname, 'w') as ofile:
-            ofile.write('prefix={}\n'.format(self._escape(prefix)))
-            ofile.write('libdir={}\n'.format(self._escape('${prefix}' / libdir)))
-            ofile.write('includedir={}\n'.format(self._escape('${prefix}' / incdir)))
+            if not uninstalled:
+                prefix = PurePath(coredata.get_builtin_option('prefix'))
+                # These always return paths relative to prefix
+                libdir = PurePath(coredata.get_builtin_option('libdir'))
+                incdir = PurePath(coredata.get_builtin_option('includedir'))
+                ofile.write('prefix={}\n'.format(self._escape(prefix)))
+                ofile.write('libdir={}\n'.format(self._escape('${prefix}' / libdir)))
+                ofile.write('includedir={}\n'.format(self._escape('${prefix}' / incdir)))
+            else:
+                ofile.write('prefix=\n')
+                ofile.write('libdir=\n')
+                ofile.write('includedir=\n')
             if variables:
                 ofile.write('\n')
             for k, v in variables:
@@ -276,7 +287,10 @@ def generate_libs_flags(libs):
                         install_dir = l.get_custom_install_dir()[0]
                         if install_dir is False:
                             continue
-                        if isinstance(install_dir, str):
+                        if uninstalled:
+                            path = os.path.dirname(state.backend.get_target_filename_abs(l))
+                            Lflag = '-L%s' % self._escape(path)
+                        elif isinstance(install_dir, str):
                             Lflag = '-L${prefix}/%s ' % self._escape(self._make_relative(prefix, install_dir))
                         else:  # install_dir is True
                             Lflag = '-L${libdir}'
@@ -290,22 +304,42 @@ def generate_libs_flags(libs):
                             mlog.warning(msg.format(l.name, 'name_suffix', lname, pcfile))
                         yield '-l%s' % lname
 
+            def generate_include_flags(libs):
+                Iflags = []
+                for l in libs:
+                    if isinstance(l, str):
+                        continue
+                    for i in l.get_include_dirs():
+                        curdir = i.get_curdir()
+                        for d in i.get_incdirs():
+                            for basedir in [state.environment.get_source_dir(),
+                                            state.environment.get_build_dir()]:
+                                path = os.path.join(basedir, curdir, d)
+                                Iflag = '-I%s' % path
+                                if Iflag not in Iflags:
+                                    Iflags.append(Iflag)
+                                    yield Iflag
+
             if len(deps.pub_libs) > 0:
                 ofile.write('Libs: {}\n'.format(' '.join(generate_libs_flags(deps.pub_libs))))
             if len(deps.priv_libs) > 0:
                 ofile.write('Libs.private: {}\n'.format(' '.join(generate_libs_flags(deps.priv_libs))))
             ofile.write('Cflags:')
-            for h in subdirs:
-                ofile.write(' ')
-                if h == '.':
-                    ofile.write('-I${includedir}')
-                else:
-                    ofile.write(self._escape(PurePath('-I${includedir}') / h))
+            if uninstalled:
+                ofile.write(' '.join(generate_include_flags(deps.pub_libs + deps.priv_libs)))
+            else:
+                for h in subdirs:
+                    ofile.write(' ')
+                    if h == '.':
+                        ofile.write('-I${includedir}')
+                    else:
+                        ofile.write(self._escape(PurePath('-I${includedir}') / h))
             for f in deps.cflags:
                 ofile.write(' ')
                 ofile.write(self._escape(f))
             ofile.write('\n')
 
+    @FeatureNewKwargs('pkgconfig.generate', '0.49.0', ['uninstalled_variables'])
     @FeatureNewKwargs('pkgconfig.generate', '0.42.0', ['extra_cflags'])
     @FeatureNewKwargs('pkgconfig.generate', '0.41.0', ['variables'])
     @permittedKwargs({'libraries', 'version', 'name', 'description', 'filebase',
@@ -400,6 +434,13 @@ def parse_variable_list(stringlist):
         self.generate_pkgconfig_file(state, deps, subdirs, name, description, url,
                                      version, pcfile, conflicts, variables)
         res = build.Data(mesonlib.File(True, state.environment.get_scratch_dir(), pcfile), pkgroot)
+
+        variables = parse_variable_list(mesonlib.stringlistify(kwargs.get('uninstalled_variables', [])))
+        pcfile = filebase + '-uninstalled.pc'
+        self.generate_pkgconfig_file(state, deps, subdirs, name, description, url,
+                                     version, pcfile, conflicts, variables,
+                                     uninstalled=True)
+
         return ModuleReturnValue(res, [res])
 
 def initialize(*args, **kwargs):