[libcxx-commits] [libcxx] [libc++] Add a merge driver that can apply clang-format (PR #73712)

[Bruno De Fraine via libcxx-commits]

================
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# This script can be installed in .git/config to allow rebasing old patches across
+# libc++'s clang-format of the whole tree. Most contributors should not require that
+# since they don't have many pre-clang-format patches lying around. This script is to
+# make it easier for contributors that do have such patches.
+#
+# The script is installed by running the following from the root of your repository:
+#
+#   $ git config merge.libcxx-reformat.name "Run clang-format when rebasing libc++ patches"
+#   $ git config merge.libcxx-reformat.driver "libcxx/utils/clang-format-merge-driver.sh %O %A %B %P"
+#   $ git config merge.libcxx-reformat.recursive binary
+#
+# This is based on https://github.com/nico/hack/blob/main/notes/auto_git_rebase_across_mechanical_changes.md.
+# Many thanks to Nico Weber for paving the way here.
+
+# Path to the file's contents at the ancestor's version.
+base=$1
+
+# Path to the file's contents at the current version.
+current=$2
+
+# Path to the file's contents at the other branch's version (for nonlinear histories, there might be multiple other branches).
+other=$3
+
+# The path of the file in the repository.
+path=$4
+
+clang-format --style=file --assume-filename=$path < $base > $base.tmp
+mv $base.tmp $base
+
+clang-format --style=file --assume-filename=$path < $current > $current.tmp
+mv $current.tmp $current
+
+clang-format --style=file --assume-filename=$path < $other > $other.tmp
+mv $other.tmp $other
+
+git merge-file $current $base $other
----------------
brunodf-snps wrote:

I noticed that too, the invocation on Nico's wiki page has the arguments in the wrong order (but the labels are still in the correct order). In your new version where you added the labels, it is all fine.

https://github.com/llvm/llvm-project/pull/73712