[llvm] [DRAFT][clang-format] helper script for resolving downstream reformat… (PR #80462)

[Bruno De Fraine via llvm-commits]

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+#!/usr/bin/env bash
+
+# Usage:
+#     If clang-format is not on PATH:
+#         export CLANG_FORMAT_PATH=/path/to/clang-format
+#     Run this script to resolve the formatting conflicts and leave only
+#     the non-formatting conflicts for you to resolve manually.
+
+# Find the .git directory.
+GIT_DIR=$(git rev-parse --git-dir)
+
+# Are we in the midst of a merge? If not, this is the wrong tool.
+if [ ! -e $GIT_DIR/MERGE_HEAD ]; then
+    echo Not doing a merge?
+    exit -1
+fi
+
+# Find the "current" "other" and "base" commits.
+# The commit we are merging into.
+read CURRENT < $GIT_DIR/ORIG_HEAD
+# The commit being merged into CURRENT.
+read OTHER < $GIT_DIR/MERGE_HEAD
+# Where it all started.
+BASE=$(git merge-base $CURRENT $OTHER)
+
+# Set up a place to keep temp files.
+MYTEMP=$(mktemp -d)
+trap 'rm -rf $MYTEMP' EXIT
+
+# Find clang-format the same way code-format-helper.py does.
+if [ -x "$CLANG_FORMAT_PATH" ]
+then
+    CLANG_FORMAT=$CLANG_FORMAT_PATH
+else
+    CLANG_FORMAT=$(which clang-format)
+    if [ ! $? ]
+    then
+        echo clang-format not found on PATH
+        exit -1
+    fi
+fi
+
+# resolve_one_file will perform formatting-conflict resolution on one file.
+# If any conflicts remain, informs the user, otherwise will git-add the
+# resolved file.
+resolve_one_file() {
+    file=$1
+    echo Resolving "$file"...
+
+    # Get formatted copies of the base, current, and other files.
+    git show "$BASE:$file"    | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/base"
+    git show "$OTHER:$file"   | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/other"
+    git show "$CURRENT:$file" | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/current"
+
+    # Merge the formatted files and report failures.
+    git merge-file -Lcurrent -Lbase -Lother "$MYTEMP/current" "$MYTEMP/base" "$MYTEMP/other"
+    STATUS=$?
+    if [ $STATUS -lt 0 ]
+    then
+        echo git merge-file failed for "$file"
+    else
+        mv "$MYTEMP/current" "$file"
+        if [ $STATUS -eq 0 ]
+        then
+            git add "$file"
+        else
+            echo Conflicts remain in $file
+        fi
+    fi
+}
+
+# Find all the conflicted files, and operate on each one.
+# `git status --porcelain` identifies conflicted files with 'UU ' prefix.
+# No other prefix is relevant here.
+git status --porcelain | grep '^UU ' | cut -c 4- | \
+    while read -r file
+    do
+        resolve_one_file "$file"
+    done
----------------
brunodf-snps wrote:

This will only work if you invoke the script from the top-level directory of the working copy? I think you can in any case get a valid filename by prefixing it with the output `git rev-parse --show-cdup`. But be sure to check if that is sufficient for the other commands inside resolve_one_file. (If too difficult, the script could error out when not in the top-level.)

https://github.com/llvm/llvm-project/pull/80462