Can read project version from a file.

docs/markdown/Reference-manual.md

@@ -1432,7 +1432,9 @@ Project supports the following keyword arguments.
 
 - `version`: which is a free form string describing the version of
   this project. You can access the value in your Meson build files
-  with `meson.project_version()`.
+  with `meson.project_version()`. Since 0.57.0 this can also be a
+  `File` object pointing to a file that contains exactly one line of
+  text.
 
 ### run_command()
 

docs/markdown/snippets/versionfile.md

@@ -0,0 +1,12 @@
+## Project version can be specified with a file
+
+Meson can be instructed to load project's version string from an
+external file like this:
+
+```meson
+project('foo', 'c' version: files('VERSION'))
+```
+
+The version file must contain exactly one line of text and that will
+be set as the project's version. If the line ends in a newline
+character, it is removed.

mesonbuild/interpreter.py

@@ -1,4 +1,4 @@
-# Copyright 2012-2019 The Meson development team
+# Copyright 2012-2021 The Meson development team
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -3181,9 +3181,29 @@ external dependencies (including libraries) must go to "dependencies".''')
         if not self.is_subproject():
             self.build.project_name = proj_name
         self.active_projectname = proj_name
-        self.project_version = kwargs.get('version', 'undefined')
-        if not isinstance(self.project_version, str):
-            raise InvalidCode('The version keyword argument must be a string.')
+        version = kwargs.get('version', 'undefined')
+        if isinstance(version, list):
+            if len(version) != 1:
+                raise InvalidCode('Version argument is an array with more than one entry.')
+            version = version[0]
+        if isinstance(version, mesonlib.File):
+            FeatureNew.single_use('version from file', '0.57.0', self.subproject)
+            self.add_build_def_file(version)
+            ifname = version.absolute_path(self.environment.source_dir,
+                                           self.environment.build_dir)
+            try:
+                ver_data = Path(ifname).read_text(encoding='utf-8').split('\n')
+            except FileNotFoundError:
+                raise InterpreterException('Version file not found.')
+            if len(ver_data) == 2 and ver_data[1] == '':
+                ver_data = ver_data[0:1]
+            if len(ver_data) != 1:
+                raise InterpreterException('Version file must contain exactly one line of text.')
+            self.project_version = ver_data[0]
+        elif isinstance(version, str):
+            self.project_version = version
+        else:
+            raise InvalidCode('The version keyword argument must be a string or a file.')
         if self.build.project_version is None:
             self.build.project_version = self.project_version
         proj_license = mesonlib.stringlistify(kwargs.get('license', 'unknown'))

run_unittests.py

@@ -5212,6 +5212,12 @@ class AllPlatformTests(BasePlatformTests):
             os.utime(str(cmakefile))
         self.assertReconfiguredBuildIsNoop()
 
+    def test_version_file(self):
+        srcdir = os.path.join(self.common_test_dir, '2 cpp')
+        self.init(srcdir)
+        projinfo = self.introspect('--projectinfo')
+        self.assertEqual(projinfo['version'], '1.0.0')
+
 
 class FailureTests(BasePlatformTests):
     '''

test cases/common/2 cpp/VERSION

@@ -0,0 +1 @@
+1.0.0

test cases/common/2 cpp/meson.build

@@ -1,4 +1,4 @@
-project('c++ test', 'cpp')
+project('c++ test', 'cpp', version: files('VERSION'))
 
 cpp = meson.get_compiler('cpp')
 if cpp.get_id() == 'intel'