pkgconfig: add suppport for custom variables during generation

Usage:
    pkgconfig.generate(
      ...
      description : 'A library with custom variables.',
      variables : ['foo=bar', 'datadir=${prefix}/data']
      )

The variables 'prefix', 'libdir' and 'includedir' are reserved, meson will
fail with an error message.

Variables can reference each other with the pkgconfig notation, e.g.

   variables : ['datadir=${prefix}/data',
                'otherdatadir=${datadir}/other']

meson does not check this for correctness or that the referenced variable
exists, we merely keep the same order as specified.

17 files changed, 159 insertions, 3 deletions

diff --git a/docs/markdown/Pkgconfig-module.md b/docs/markdown/Pkgconfig-module.md
index 51fe6b2..6b9a968 100644
--- a/docs/markdown/Pkgconfig-module.md
+++ b/docs/markdown/Pkgconfig-module.md
@@ -20,3 +20,4 @@ The generated file's properties are specified with the following keyword argumen
 - `requires_private` list of strings to put in the `Requires.private` field
 - `libraries_private` list of strings to put in the `Libraries.private` field
 - `install_dir` the directory to install to, defaults to the value of option `libdir` followed by `/pkgconfig`
+- `variables` a list of strings with custom variables to add to the generated file. The strings must be in the form `name=value` and may reference other pkgconfig variables, e.g. `datadir=${prefix}/share`. The names `prefix`, `libdir` and `installdir` are reserved and may not be used.
diff --git a/docs/markdown/Release-notes-for-0.41.0.md b/docs/markdown/Release-notes-for-0.41.0.md
index a2a64de..8a7f263 100644
--- a/docs/markdown/Release-notes-for-0.41.0.md
+++ b/docs/markdown/Release-notes-for-0.41.0.md
@@ -24,3 +24,17 @@ The ninja backend now quotes special characters that may be interpreted by
 ninja itself, providing better interoperability with custom commands. This
 support may not be perfect; please report any issues found with special
 characters to the issue tracker.
+
+## Pkgconfig support for custom variables
+
+The Pkgconfig module object can add arbitrary variables to the generated .pc
+file with the new `variables` keyword:
+```meson
+pkg.generate(libraries : libs,
+             subdirs : h,
+             version : '1.0',
+             name : 'libsimple',
+             filebase : 'simple',
+             description : 'A simple demo library.',
+             variables : ['datadir=${prefix}/data'])
+```
diff --git a/mesonbuild/modules/pkgconfig.py b/mesonbuild/modules/pkgconfig.py
index e79371f..09c615a 100644
--- a/mesonbuild/modules/pkgconfig.py
+++ b/mesonbuild/modules/pkgconfig.py
@@ -43,7 +43,7 @@ class PkgConfigModule(ExtensionModule):
 
     def generate_pkgconfig_file(self, state, libraries, subdirs, name, description,
                                 url, version, pcfile, pub_reqs, priv_reqs,
-                                conflicts, priv_libs):
+                                conflicts, priv_libs, variables):
         coredata = state.environment.get_coredata()
         outdir = state.environment.scratch_dir
         fname = os.path.join(outdir, pcfile)
@@ -53,6 +53,8 @@ class PkgConfigModule(ExtensionModule):
             # 'os.path.join' for details)
             ofile.write('libdir=%s\n' % os.path.join('${prefix}', coredata.get_builtin_option('libdir')))
             ofile.write('includedir=%s\n' % os.path.join('${prefix}', coredata.get_builtin_option('includedir')))
+            for k, v in variables:
+                ofile.write('%s=%s\n' % (k, v))
             ofile.write('\n')
             ofile.write('Name: %s\n' % name)
             if len(description) > 0:
@@ -136,6 +138,33 @@ class PkgConfigModule(ExtensionModule):
         pub_reqs = mesonlib.stringlistify(kwargs.get('requires', []))
         priv_reqs = mesonlib.stringlistify(kwargs.get('requires_private', []))
         conflicts = mesonlib.stringlistify(kwargs.get('conflicts', []))
+
+        def parse_variable_list(stringlist):
+            reserved = ['prefix', 'libdir', 'includedir']
+            variables = []
+            for var in stringlist:
+                # foo=bar=baz is ('foo', 'bar=baz')
+                l = var.split('=', 1)
+                if len(l) < 2:
+                    raise mesonlib.MesonException('Variables must be in \'name=value\' format')
+
+                name, value = l[0].strip(), l[1].strip()
+                if not name or not value:
+                    raise mesonlib.MesonException('Variables must be in \'name=value\' format')
+
+                # Variable names must not contain whitespaces
+                if any(c.isspace() for c in name):
+                    raise mesonlib.MesonException('Invalid whitespace in assignment "{}"'.format(var))
+
+                if name in reserved:
+                    raise mesonlib.MesonException('Variable "{}" is reserved'.format(name))
+
+                variables.append((name, value))
+
+            return variables
+
+        variables = parse_variable_list(mesonlib.stringlistify(kwargs.get('variables', [])))
+
         pcfile = filebase + '.pc'
         pkgroot = kwargs.get('install_dir', None)
         if pkgroot is None:
@@ -144,7 +173,7 @@ class PkgConfigModule(ExtensionModule):
             raise mesonlib.MesonException('Install_dir must be a string.')
         self.generate_pkgconfig_file(state, libs, subdirs, name, description, url,
                                      version, pcfile, pub_reqs, priv_reqs,
-                                     conflicts, priv_libs)
+                                     conflicts, priv_libs, variables)
         res = build.Data(mesonlib.File(True, state.environment.get_scratch_dir(), pcfile), pkgroot)
         return ModuleReturnValue(res, [res])
 
diff --git a/run_unittests.py b/run_unittests.py
index ed98cad..86e5a98 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -1174,6 +1174,8 @@ class LinuxlikeTests(BasePlatformTests):
         self.assertTrue(simple_dep.found())
         self.assertEqual(simple_dep.get_version(), '1.0')
         self.assertIn('-lfoo', simple_dep.get_link_args())
+        self.assertEqual(simple_dep.get_pkgconfig_variable('foo'), 'bar')
+        self.assertPathEqual(simple_dep.get_pkgconfig_variable('datadir'), '/usr/data')
 
     def test_vala_c_warnings(self):
         '''
diff --git a/test cases/common/51 pkgconfig-gen/meson.build b/test cases/common/51 pkgconfig-gen/meson.build
index e1e41d9..68ee812 100644
--- a/test cases/common/51 pkgconfig-gen/meson.build
+++ b/test cases/common/51 pkgconfig-gen/meson.build
@@ -41,4 +41,6 @@ pkgg.generate(
   libraries : lib2,
   name : 'libfoo',
   version : libver,
-  description : 'A foo library.')
+  description : 'A foo library.',
+  variables : ['foo=bar', 'datadir=${prefix}/data']
+)
diff --git a/test cases/failing/47 pkgconfig variables reserved/meson.build b/test cases/failing/47 pkgconfig variables reserved/meson.build
new file mode 100644
index 0000000..82ae995
--- /dev/null
+++ b/test cases/failing/47 pkgconfig variables reserved/meson.build
@@ -0,0 +1,16 @@
+project('variables-reserved-test', 'c', version : '1.0')
+
+pkgg = import('pkgconfig')
+lib = shared_library('simple', 'simple.c')
+libver = '1.0'
+h = install_headers('simple.h')
+
+pkgg.generate(
+  libraries : [lib, '-lz'],
+  subdirs : '.',
+  version : libver,
+  name : 'libsimple',
+  filebase : 'simple',
+  description : 'A simple demo library.',
+  variables : [ 'prefix=/tmp/' ]
+)
diff --git a/test cases/failing/47 pkgconfig variables reserved/simple.c b/test cases/failing/47 pkgconfig variables reserved/simple.c
new file mode 100644
index 0000000..e8a6d83
--- /dev/null
+++ b/test cases/failing/47 pkgconfig variables reserved/simple.c
@@ -0,0 +1,5 @@
+#include"simple.h"
+
+int simple_function() {
+    return 42;
+}
diff --git a/test cases/failing/47 pkgconfig variables reserved/simple.h b/test cases/failing/47 pkgconfig variables reserved/simple.h
new file mode 100644
index 0000000..bb52e6d
--- /dev/null
+++ b/test cases/failing/47 pkgconfig variables reserved/simple.h
@@ -0,0 +1,6 @@
+#ifndef SIMPLE_H_
+#define SIMPLE_H_
+
+int simple_function();
+
+#endif
diff --git a/test cases/failing/48 pkgconfig variables zero length/meson.build b/test cases/failing/48 pkgconfig variables zero length/meson.build
new file mode 100644
index 0000000..65d3344
--- /dev/null
+++ b/test cases/failing/48 pkgconfig variables zero length/meson.build
@@ -0,0 +1,16 @@
+project('variables-zero-length-test', 'c', version : '1.0')
+
+pkgg = import('pkgconfig')
+lib = shared_library('simple', 'simple.c')
+libver = '1.0'
+h = install_headers('simple.h')
+
+pkgg.generate(
+  libraries : [lib, '-lz'],
+  subdirs : '.',
+  version : libver,
+  name : 'libsimple',
+  filebase : 'simple',
+  description : 'A simple demo library.',
+  variables : [ '=value' ]
+)
diff --git a/test cases/failing/48 pkgconfig variables zero length/simple.c b/test cases/failing/48 pkgconfig variables zero length/simple.c
new file mode 100644
index 0000000..e8a6d83
--- /dev/null
+++ b/test cases/failing/48 pkgconfig variables zero length/simple.c
@@ -0,0 +1,5 @@
+#include"simple.h"
+
+int simple_function() {
+    return 42;
+}
diff --git a/test cases/failing/48 pkgconfig variables zero length/simple.h b/test cases/failing/48 pkgconfig variables zero length/simple.h
new file mode 100644
index 0000000..bb52e6d
--- /dev/null
+++ b/test cases/failing/48 pkgconfig variables zero length/simple.h
@@ -0,0 +1,6 @@
+#ifndef SIMPLE_H_
+#define SIMPLE_H_
+
+int simple_function();
+
+#endif
diff --git a/test cases/failing/49 pkgconfig variables zero length value/meson.build b/test cases/failing/49 pkgconfig variables zero length value/meson.build
new file mode 100644
index 0000000..33977b2
--- /dev/null
+++ b/test cases/failing/49 pkgconfig variables zero length value/meson.build
@@ -0,0 +1,16 @@
+project('variables-zero-length-value-test', 'c', version : '1.0')
+
+pkgg = import('pkgconfig')
+lib = shared_library('simple', 'simple.c')
+libver = '1.0'
+h = install_headers('simple.h')
+
+pkgg.generate(
+  libraries : [lib, '-lz'],
+  subdirs : '.',
+  version : libver,
+  name : 'libsimple',
+  filebase : 'simple',
+  description : 'A simple demo library.',
+  variables : [ 'key=' ]
+)
diff --git a/test cases/failing/49 pkgconfig variables zero length value/simple.c b/test cases/failing/49 pkgconfig variables zero length value/simple.c
new file mode 100644
index 0000000..e8a6d83
--- /dev/null
+++ b/test cases/failing/49 pkgconfig variables zero length value/simple.c
@@ -0,0 +1,5 @@
+#include"simple.h"
+
+int simple_function() {
+    return 42;
+}
diff --git a/test cases/failing/49 pkgconfig variables zero length value/simple.h b/test cases/failing/49 pkgconfig variables zero length value/simple.h
new file mode 100644
index 0000000..bb52e6d
--- /dev/null
+++ b/test cases/failing/49 pkgconfig variables zero length value/simple.h
@@ -0,0 +1,6 @@
+#ifndef SIMPLE_H_
+#define SIMPLE_H_
+
+int simple_function();
+
+#endif
diff --git a/test cases/failing/50 pkgconfig variables not key value/meson.build b/test cases/failing/50 pkgconfig variables not key value/meson.build
new file mode 100644
index 0000000..02fa737
--- /dev/null
+++ b/test cases/failing/50 pkgconfig variables not key value/meson.build
@@ -0,0 +1,16 @@
+project('variables-not-key-value-test', 'c', version : '1.0')
+
+pkgg = import('pkgconfig')
+lib = shared_library('simple', 'simple.c')
+libver = '1.0'
+h = install_headers('simple.h')
+
+pkgg.generate(
+  libraries : [lib, '-lz'],
+  subdirs : '.',
+  version : libver,
+  name : 'libsimple',
+  filebase : 'simple',
+  description : 'A simple demo library.',
+  variables : [ 'this_should_be_key_value' ]
+)
diff --git a/test cases/failing/50 pkgconfig variables not key value/simple.c b/test cases/failing/50 pkgconfig variables not key value/simple.c
new file mode 100644
index 0000000..e8a6d83
--- /dev/null
+++ b/test cases/failing/50 pkgconfig variables not key value/simple.c
@@ -0,0 +1,5 @@
+#include"simple.h"
+
+int simple_function() {
+    return 42;
+}
diff --git a/test cases/failing/50 pkgconfig variables not key value/simple.h b/test cases/failing/50 pkgconfig variables not key value/simple.h
new file mode 100644
index 0000000..bb52e6d
--- /dev/null
+++ b/test cases/failing/50 pkgconfig variables not key value/simple.h
@@ -0,0 +1,6 @@
+#ifndef SIMPLE_H_
+#define SIMPLE_H_
+
+int simple_function();
+
+#endif