vcs_tag: document the already supported file arg

docs/yaml/functions/vcs_tag.yaml

@@ -22,7 +22,7 @@ description: |
 
 kwargs:
   command:
-    type: list[str]
+    type: list[str | file]
     description: |
       The command to execute, see [[custom_target]] for details
       on how this command must be specified.
@@ -30,6 +30,8 @@ kwargs:
       This parameter is optional. If it is absent, Meson will try
       its best to find a suitable default command.
 
+      *(since 0.62.0)* [[@file]] is accepted.
+
   input:
     type: str
     required: true

mesonbuild/interpreter/interpreter.py

@@ -1731,6 +1731,8 @@ external dependencies (including libraries) must go to "dependencies".''')
         vcs_cmd = kwargs['command']
         source_dir = os.path.normpath(os.path.join(self.environment.get_source_dir(), self.subdir))
         if vcs_cmd:
+            if isinstance(vcs_cmd[0], mesonlib.File):
+                FeatureNew.single_use('vcs_tag with file as the first argument', '0.62.0', self.subproject, location=node)
             maincmd = self.find_program_impl(vcs_cmd[0], required=False)
             if maincmd.found():
                 vcs_cmd[0] = maincmd

test cases/common/66 vcstag/meson.build

@@ -17,7 +17,12 @@ fallback : '1.0.0')
 version_src_fallback = vcs_tag(input : 'vcstag.c.in',
 output : 'vcstag-fallback.c')
 
+version_src_file = vcs_tag(input : 'vcstag.c.in',
+output : 'vcstag-file.c',
+command : files('version.py'))
+
 executable('tagprog', 'tagprog.c', version_src)
 executable('tagprog-custom', 'tagprog.c', version_src_custom)
 executable('tagprog-fallback', 'tagprog.c', version_src_fallback)
 executable('tagprog-notfound-fallback', 'tagprog.c', version_src_notfound_fallback)
+executable('tagprog-file', 'tagprog.c', version_src_file)

test cases/common/66 vcstag/version.py

@@ -0,0 +1,3 @@
+#!/usr/bin/env python3
+
+print('3.14')