machine file: Add @GLOBAL_SOURCE_ROOT@ and @DIRNAME@

6 files changed, 51 insertions, 15 deletions

diff --git a/docs/markdown/Machine-files.md b/docs/markdown/Machine-files.md
index c300769..a3e876d 100644
--- a/docs/markdown/Machine-files.md
+++ b/docs/markdown/Machine-files.md
@@ -128,6 +128,18 @@ b = a + 'World'
 a = 'Hello'
 ```
 
+*Since 1.3.0* Some tokens are replaced in the machine file before parsing it:
+- `@GLOBAL_SOURCE_ROOT@`: the absolute path to the project's source tree
+- `@DIRNAME@`: the absolute path to the machine file's parent directory.
+
+It can be used, for example, to have paths relative to the source directory, or
+relative to toolchain's installation directory.
+```ini
+[binaries]
+c = '@DIRNAME@/toolchain/gcc'
+exe_wrapper = '@GLOBAL_SOURCE_ROOT@' / 'build-aux' / 'my-exe-wrapper.sh'
+```
+
 ### Binaries
 
 The binaries section contains a list of binaries. These can be used
diff --git a/docs/markdown/snippets/machine_file_source_dir.md b/docs/markdown/snippets/machine_file_source_dir.md
new file mode 100644
index 0000000..5af344e
--- /dev/null
+++ b/docs/markdown/snippets/machine_file_source_dir.md
@@ -0,0 +1,13 @@
+## `@GLOBAL_SOURCE_ROOT@` and `@DIRNAME@` in machine files
+
+Some tokens are now replaced in the machine file before parsing it:
+- `@GLOBAL_SOURCE_ROOT@`: the absolute path to the project's source tree
+- `@DIRNAME@`: the absolute path to the machine file's parent directory.
+
+It can be used, for example, to have paths relative to the source directory, or
+relative to toolchain's installation directory.
+```ini
+[binaries]
+c = '@DIRNAME@/toolchain/gcc'
+exe_wrapper = '@GLOBAL_SOURCE_ROOT@' / 'build-aux' / 'my-exe-wrapper.sh'
+```
diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index bb84f72..d59d9b8 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -964,15 +964,20 @@ class CmdLineFileParser(configparser.ConfigParser):
         return optionstr
 
 class MachineFileParser():
-    def __init__(self, filenames: T.List[str]) -> None:
+    def __init__(self, filenames: T.List[str], sourcedir: str) -> None:
         self.parser = CmdLineFileParser()
         self.constants: T.Dict[str, T.Union[str, bool, int, T.List[str]]] = {'True': True, 'False': False}
         self.sections: T.Dict[str, T.Dict[str, T.Union[str, bool, int, T.List[str]]]] = {}
 
-        try:
-            self.parser.read(filenames)
-        except configparser.Error as e:
-            raise EnvironmentException(f'Malformed cross or native file: {e}')
+        for fname in filenames:
+            with open(fname, encoding='utf-8') as f:
+                content = f.read()
+                content = content.replace('@GLOBAL_SOURCE_ROOT@', sourcedir)
+                content = content.replace('@DIRNAME@', os.path.dirname(fname))
+                try:
+                    self.parser.read_string(content, fname)
+                except configparser.Error as e:
+                    raise EnvironmentException(f'Malformed machine file: {e}')
 
         # Parse [constants] first so they can be used in other sections
         if self.parser.has_section('constants'):
@@ -1028,8 +1033,8 @@ class MachineFileParser():
                     return os.path.join(l, r)
         raise EnvironmentException('Unsupported node type')
 
-def parse_machine_files(filenames: T.List[str]):
-    parser = MachineFileParser(filenames)
+def parse_machine_files(filenames: T.List[str], sourcedir: str):
+    parser = MachineFileParser(filenames, sourcedir)
     return parser.sections
 
 def get_cmd_line_file(build_dir: str) -> str:
diff --git a/mesonbuild/environment.py b/mesonbuild/environment.py
index ab6f56c..36106e4 100644
--- a/mesonbuild/environment.py
+++ b/mesonbuild/environment.py
@@ -477,7 +477,7 @@ class Environment:
     log_dir = 'meson-logs'
     info_dir = 'meson-info'
 
-    def __init__(self, source_dir: T.Optional[str], build_dir: T.Optional[str], options: 'argparse.Namespace') -> None:
+    def __init__(self, source_dir: str, build_dir: str, options: 'argparse.Namespace') -> None:
         self.source_dir = source_dir
         self.build_dir = build_dir
         # Do not try to create build directories when build_dir is none.
@@ -550,7 +550,7 @@ class Environment:
         ## Read in native file(s) to override build machine configuration
 
         if self.coredata.config_files is not None:
-            config = coredata.parse_machine_files(self.coredata.config_files)
+            config = coredata.parse_machine_files(self.coredata.config_files, self.source_dir)
             binaries.build = BinaryTable(config.get('binaries', {}))
             properties.build = Properties(config.get('properties', {}))
             cmakevars.build = CMakeVariables(config.get('cmake', {}))
@@ -561,7 +561,7 @@ class Environment:
         ## Read in cross file(s) to override host machine configuration
 
         if self.coredata.cross_files:
-            config = coredata.parse_machine_files(self.coredata.cross_files)
+            config = coredata.parse_machine_files(self.coredata.cross_files, self.source_dir)
             properties.host = Properties(config.get('properties', {}))
             binaries.host = BinaryTable(config.get('binaries', {}))
             cmakevars.host = CMakeVariables(config.get('cmake', {}))
diff --git a/run_project_tests.py b/run_project_tests.py
index acfa284..f279332 100755
--- a/run_project_tests.py
+++ b/run_project_tests.py
@@ -793,7 +793,7 @@ def _skip_keys(test_def: T.Dict) -> T.Tuple[bool, bool]:
 
     # Test is expected to skip if os matches
     if 'skip_on_os' in test_def:
-        mesonenv = environment.Environment(None, None, get_fake_options('/'))
+        mesonenv = environment.Environment('', '', get_fake_options('/'))
         for skip_os in test_def['skip_on_os']:
             if skip_os.startswith('!'):
                 if mesonenv.machines.host.system != skip_os[1:]:
@@ -966,7 +966,7 @@ def have_d_compiler() -> bool:
 
 def have_objc_compiler(use_tmp: bool) -> bool:
     with TemporaryDirectoryWinProof(prefix='b ', dir=None if use_tmp else '.') as build_dir:
-        env = environment.Environment(None, build_dir, get_fake_options('/'))
+        env = environment.Environment('', build_dir, get_fake_options('/'))
         try:
             objc_comp = detect_objc_compiler(env, MachineChoice.HOST)
         except mesonlib.MesonException:
@@ -982,7 +982,7 @@ def have_objc_compiler(use_tmp: bool) -> bool:
 
 def have_objcpp_compiler(use_tmp: bool) -> bool:
     with TemporaryDirectoryWinProof(prefix='b ', dir=None if use_tmp else '.') as build_dir:
-        env = environment.Environment(None, build_dir, get_fake_options('/'))
+        env = environment.Environment('', build_dir, get_fake_options('/'))
         try:
             objcpp_comp = detect_objcpp_compiler(env, MachineChoice.HOST)
         except mesonlib.MesonException:
@@ -1458,7 +1458,7 @@ def detect_system_compiler(options: 'CompilerArgumentType') -> None:
     if options.native_file:
         fake_opts.native_file = [options.native_file]
 
-    env = environment.Environment(None, None, fake_opts)
+    env = environment.Environment('', '', fake_opts)
 
     print_compilers(env, MachineChoice.HOST)
     if options.cross_file:
diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 819cc2e..b5252f7 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -3982,17 +3982,23 @@ class AllPlatformTests(BasePlatformTests):
                     [properties]
                     c_args = common_flags + ['-DSOMETHING']
                     cpp_args = c_args + ['-DSOMETHING_ELSE']
+                    rel_to_src = '@GLOBAL_SOURCE_ROOT@' / 'tool'
+                    rel_to_file = '@DIRNAME@' / 'tool'
+                    no_escaping = '@@DIRNAME@@' / 'tool'
 
                     [binaries]
                     c = toolchain / compiler
                     '''))
 
-            values = mesonbuild.coredata.parse_machine_files([crossfile1, crossfile2])
+            values = mesonbuild.coredata.parse_machine_files([crossfile1, crossfile2], self.builddir)
             self.assertEqual(values['binaries']['c'], '/toolchain/gcc')
             self.assertEqual(values['properties']['c_args'],
                              ['--sysroot=/toolchain/sysroot', '-DSOMETHING'])
             self.assertEqual(values['properties']['cpp_args'],
                              ['--sysroot=/toolchain/sysroot', '-DSOMETHING', '-DSOMETHING_ELSE'])
+            self.assertEqual(values['properties']['rel_to_src'], os.path.join(self.builddir, 'tool'))
+            self.assertEqual(values['properties']['rel_to_file'], os.path.join(os.path.dirname(crossfile2), 'tool'))
+            self.assertEqual(values['properties']['no_escaping'], os.path.join(f'@{os.path.dirname(crossfile2)}@', 'tool'))
 
     @skipIf(is_windows(), 'Directory cleanup fails for some reason')
     def test_wrap_git(self):