pkgconfig: Generate -uninstalled.pc files

Closes: mesonbuild#3472.

docs/markdown/Pkgconfig-module.md

@@ -54,6 +54,8 @@ keyword arguments.
   `Version:` field. Defaults to the project version if unspecified.
 - `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
@@ -62,6 +64,15 @@ provided for all required fields of the pc file:
 - `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>/meson-uninstalled/`. It is sometimes
+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>/meson-uninstalled` before building your
+application. That will cause pkg-config to prefer those `-uninstalled.pc` files
+and find libraries and headers from the meson builddir. This is an experimental
+feature provided on a best-effort basis, it might not work in all use-cases.
+
 ### Implicit dependencies
 
 The exact rules followed to find dependencies that are implicitly added into the

docs/markdown/snippets/uninstalled-pkgconfig.md

@@ -0,0 +1,8 @@
+## 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>/meson-uninstalled`. They can be used to build applications against
+libraries built by meson without installing them, by pointing `PKG_CONFIG_PATH`
+to that directory. This is an experimental feature provided on a best-effort
+basis, it might not work in all use-cases.

mesonbuild/modules/pkgconfig.py

@@ -210,6 +210,9 @@ def _fn(xs, libs=False):
         self.priv_reqs = [i for i in self.priv_reqs if i not in self.pub_reqs]
 
 class PkgConfigModule(ExtensionModule):
+    def __init__(self, interpreter):
+        super().__init__(interpreter)
+        self.uninstalled_info = []
 
     def _get_lname(self, l, msg, pcfile):
         # Nothing special
@@ -251,19 +254,30 @@ 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, 'meson-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:
@@ -292,6 +306,11 @@ def generate_libs_flags(libs):
                 for l in libs:
                     if isinstance(l, str):
                         yield l
+                    elif uninstalled:
+                        path = state.backend.get_target_filename_abs(l)
+                        if path not in Lflags:
+                            Lflags.append(path)
+                            yield path
                     else:
                         install_dir = l.get_custom_install_dir()[0]
                         if install_dir is False:
@@ -317,22 +336,41 @@ def generate_libs_flags(libs):
                         if 'cs' not in l.compilers:
                             yield '-l%s' % lname
 
+            def generate_uninstalled_cflags():
+                result = []
+                for h in state.headers:
+                    if h.subproject != state.subproject:
+                        continue
+                    for f in h.sources:
+                        if not isinstance(f, mesonlib.File):
+                            continue
+                        abspath = f.absolute_path(state.environment.get_source_dir(),
+                                                  state.environment.get_build_dir())
+                        incdir = os.path.dirname(abspath)
+                        if incdir not in result:
+                            result.append(incdir)
+                            yield '-I%s' % self._escape(incdir)
+
             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_uninstalled_cflags()))
+            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',
@@ -427,6 +465,15 @@ 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'
+        # postpone generation of uninstalled pc files because we need the complete list
+        # of installed headers, and user could call install_headers() after generating
+        # the pc file. Keep all needed information into a list that will be processed
+        # when interpreter calls _finish_subproject() method.
+        generate_pkgconfig_file_args = (deps, subdirs, name, description, url,
+                                        version, pcfile, conflicts, variables)
+        self.uninstalled_info.append((state.subproject, generate_pkgconfig_file_args))
         # Associate the main library with this generated pc file. If the library
         # is used in any subsequent call to the generated, it will generate a
         # 'Requires:' or 'Requires.private:'.
@@ -445,5 +492,12 @@ def parse_variable_list(stringlist):
                                                               lineno=state.current_lineno)
         return ModuleReturnValue(res, [res])
 
+    # Called by interpreter when it's done parsing a (sub)project
+    def _finish_subproject(self, state):
+        for info in self.uninstalled_info:
+            subproject, args = info
+            if state.subproject == subproject:
+                self.generate_pkgconfig_file(state, *args, uninstalled=True)
+
 def initialize(*args, **kwargs):
     return PkgConfigModule(*args, **kwargs)

run_unittests.py

@@ -3910,6 +3910,21 @@ def test_pkgconfig_gen_deps(self):
         out = self._run(cmd + ['--print-requires-private']).strip().split('\n')
         self.assertEqual(sorted(out), sorted(['libexposed', 'libfoo >= 1.0', 'libhello']))
 
+    def test_pkgconfig_uninstalled(self):
+        testdir = os.path.join(self.common_test_dir, '48 pkgconfig-gen')
+        self.init(testdir)
+        self.build()
+
+        os.environ['PKG_CONFIG_LIBDIR'] = os.path.join(self.builddir, 'meson-uninstalled')
+        if is_cygwin():
+                os.environ['PATH'] += os.pathsep + self.builddir
+
+        self.new_builddir()
+        testdir = os.path.join(self.common_test_dir, '48 pkgconfig-gen', 'dependencies')
+        self.init(testdir)
+        self.build()
+        self.run_tests()
+
     def test_pkg_unfound(self):
         testdir = os.path.join(self.unit_test_dir, '23 unfound pkgconfig')
         self.init(testdir)

test cases/common/48 pkgconfig-gen/dependencies/main.c

@@ -0,0 +1,6 @@
+#include <simple.h>
+
+int main(int argc, char *argv[])
+{
+  return simple_function() == 42 ? 0 : 1;
+}

test cases/common/48 pkgconfig-gen/dependencies/meson.build

@@ -18,6 +18,9 @@ threads_dep = dependency('threads')
 custom_dep = declare_dependency(link_with : custom_lib, compile_args : ['-DCUSTOM'])
 custom2_dep = declare_dependency(link_args : ['-lcustom2'], compile_args : ['-DCUSTOM2'])
 
+exe = executable('test1', 'main.c', dependencies : [pc_dep])
+test('Test1', exe)
+
 # Generate a PC file:
 # - Having libmain in libraries should pull implicitly libexposed and libinternal in Libs.private
 # - Having libexposed in libraries should remove it from Libs.private

test cases/common/48 pkgconfig-gen/meson.build

@@ -1,7 +1,6 @@
 project('pkgconfig-gen', 'c')
 
 # First check we have pkg-config >= 0.29
-
 pkgconfig = find_program('pkg-config', required: false)
 if not pkgconfig.found()
   error('MESON_SKIP_TEST: pkg-config not found')