From d31f468ad8733712db5b247299fdd4108adf07a4 Mon Sep 17 00:00:00 2001
From: Eric Engestrom <eric@igalia.com>
Date: Mon, 6 Oct 2025 17:17:51 +0200
Subject: [PATCH] Revert "meson: use vcs_tag() instead of custom script"

This reverts commit e4edf9203b3fb5b7fe27de404c5b4a200b2a3ecc.

Meson is unfortunately not quite ready yet, and prints stderr noise when
_not_ building from a git clone.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37717>
---
 .gitlab-ci.yml      |  1 +
 bin/git_sha1_gen.py | 50 +++++++++++++++++++++++++++++++++++++++++++++
 bin/meson.build     |  1 +
 src/git_sha1.h.in   |  1 -
 src/meson.build     |  9 ++++----
 5 files changed, 57 insertions(+), 5 deletions(-)
 create mode 100644 bin/git_sha1_gen.py
 delete mode 100644 src/git_sha1.h.in

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 71c0c77b559..17784cf9005 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -290,6 +290,7 @@ include:
     - if: *is-merge-attempt
       changes: &all_paths
         - VERSION
+        - bin/git_sha1_gen.py
         - bin/install_megadrivers.py
         - bin/symbols-check.py
         - bin/ci/**/*
diff --git a/bin/git_sha1_gen.py b/bin/git_sha1_gen.py
new file mode 100644
index 00000000000..a457b310d48
--- /dev/null
+++ b/bin/git_sha1_gen.py
@@ -0,0 +1,50 @@
+"""
+Generate the contents of the git_sha1.h file.
+"""
+
+import argparse
+import os
+import os.path
+import subprocess
+import sys
+
+
+def get_git_sha1():
+    """Try to get the git SHA1 with git rev-parse."""
+    git_dir = os.path.join(os.path.dirname(sys.argv[0]), '..', '.git')
+    try:
+        git_sha1 = subprocess.check_output([
+            'git',
+            '--git-dir=' + git_dir,
+            'rev-parse',
+            'HEAD',
+        ], stderr=open(os.devnull, 'w')).decode("ascii")
+    except Exception:
+        # don't print anything if it fails
+        git_sha1 = ''
+    return git_sha1
+
+
+def write_if_different(contents):
+    """
+    Avoid touching the output file if it doesn't need modifications
+    Useful to avoid triggering rebuilds when nothing has changed.
+    """
+    if os.path.isfile(args.output):
+        with open(args.output, 'r') as file:
+            if file.read() == contents:
+                return
+    with open(args.output, 'w') as file:
+        file.write(contents)
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument('--output', help='File to write the #define in',
+                    required=True)
+args = parser.parse_args()
+
+git_sha1 = os.environ.get('MESA_GIT_SHA1_OVERRIDE', get_git_sha1())[:10]
+if git_sha1:
+    write_if_different('#define MESA_GIT_SHA1 " (git-' + git_sha1 + ')"')
+else:
+    write_if_different('#define MESA_GIT_SHA1 ""')
diff --git a/bin/meson.build b/bin/meson.build
index 8749a69c349..e6664d7fe74 100644
--- a/bin/meson.build
+++ b/bin/meson.build
@@ -1,6 +1,7 @@
 # Copyright © 2017 Eric Engestrom
 # SPDX-License-Identifier: MIT
 
+git_sha1_gen_py = files('git_sha1_gen.py')
 gen_vs_module_defs_py = files('gen_vs_module_defs.py')
 gen_vs_module_defs_normal_command = [
   prog_python, gen_vs_module_defs_py,
diff --git a/src/git_sha1.h.in b/src/git_sha1.h.in
deleted file mode 100644
index 1cc80cccb63..00000000000
--- a/src/git_sha1.h.in
+++ /dev/null
@@ -1 +0,0 @@
-#define MESA_GIT_SHA1 @VCS_TAG@
diff --git a/src/meson.build b/src/meson.build
index ae9dcffad6d..fdfb2dc246f 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -33,11 +33,12 @@ glsl_util_files = files(
     'mesa/program/dummy_errors.c',
 )
 
-sha1_h = vcs_tag(
-  input : 'git_sha1.h.in',
+sha1_h = custom_target(
+  'git_sha1.h',
   output : 'git_sha1.h',
-  command : ['git', 'show', '--no-patch', '--abbrev=10', '--format=" (git-%h)"'],
-  fallback : '""',
+  command : [prog_python, git_sha1_gen_py, '--output', '@OUTPUT@'],
+  build_by_default : true,
+  build_always_stale : true, # commit sha1 can change without having touched these files
 )
 
 if cc.get_argument_syntax() == 'msvc'