[libcxx] [llvm] Add pre-commit hooks and git config for libc++ & git-clang-format. (PR #73798)

[Mark de Wever via llvm-commits]

================
@@ -0,0 +1,88 @@
+#!/bin/bash
+
+
+# Jump up to the root directory of the repository
+FORCE=${LLVM_FORCE_FORMATTING:-0}
+
+for arg in "$@"
+do
+  if [ "$arg" = "--force" ]; then
+    FORCE=1
+  fi
+done
+
+git_repo_path="$(git rev-parse --show-toplevel)"
+cd "$git_repo_path"
+
+# Set up git-clang-format config so that it formats files without extensions as needed by libc++
+function check_formatting_config() {
+  # Set the desired git config key and value
+  CONFIG_KEY=$1
+  CONFIG_VALUE=$2
+  ALLOW_DIFFERENT=$3
+
+  # Get the actual value of the config key
+  ACTUAL_VALUE=$(git config --local --get $CONFIG_KEY)
+
+  # Check if the actual value is the same as the desired value
+  if [[ "$ACTUAL_VALUE" == "$CONFIG_VALUE" ]]; then
+      echo "The git config value for $CONFIG_KEY is correctly set to $CONFIG_VALUE"
+  elif [[ "$ACTION_VALUE" != "" ]] && [[ "$ALLOW_DIFFERENT" -eq 1 ]]; then
+    echo "The git config value for $CONFIG_KEY is set to $ACTUAL_VALUE, but $CONFIG_VALUE is allowed."
+  else
+      echo "Setting up git-clang-format config for libc++..."
+      # Prompt the user to set the git config key to the desired value
+      echo "Git config key $CONFIG_KEY is not set or incorrect."
+      read -p "Would you like to set it to $CONFIG_VALUE [Y/n]? " -n $FORCE -r
+      echo
+      if [[ $REPLY =~ ^[Yy]$ ]]
+      then
+          git config --local $CONFIG_KEY "$CONFIG_VALUE"
+          echo "Git config key $CONFIG_KEY has been set to $CONFIG_VALUE"
+      else
+          echo "No changes were made to the git config."
+      fi
+  fi
+}
+
+# Check for an installation of git-clang-format
+function check_clang_format() {
+  # Check if git-clang-format is installed
+  GIT_CLANG_FORMAT_COMMAND="git-clang-format"
+  if command -v $GIT_CLANG_FORMAT_COMMAND >/dev/null 2>&1; then
+      echo "git-clang-format is installed in your system."
+  else
+      echo "Warning: git-clang-format is not installed in your system."
+  fi
+}
+# ...
+# Existing script here
+# ...
+
+# Check if libcxx-formatting.sh is installed in pre-commit hook
+function check_pre_commit_hooks() {
+  # Check if libcxx-formatting.sh is present in pre-commit hook
+  PRE_COMMIT_FILE=".git/hooks/pre-commit"
+  EXPECTED_COMMIT_SCRIPT=". ./libcxx/utils/formatting/pre-commit-formatting-hook.sh"
+  if grep -q -F "$EXPECTED_COMMIT_SCRIPT" "$PRE_COMMIT_FILE"; then
+      echo "pre-commit-formatting-hook.sh is already installed in pre-commit hook."
+  else
+      # Offer to install it
+      read -p "pre-commit-formatting-hook.sh is not installed. Would you like to install it [Y/n]? " -n $FORCE -r
+      echo
+      if [[ $REPLY =~ ^[Yy]$ ]]
+      then
+          echo "Installing pre-commit-formatting-hook.sh..."
+          echo "$EXPECTED_COMMIT_SCRIPT" >> "$PRE_COMMIT_FILE"
+          chmod +x "$PRE_COMMIT_FILE"
+          echo "Installed pre-commit-formatting-hook.sh to pre-commit hook."
+      else
+          echo "No changes were made to the pre-commit hook."
+      fi
+  fi
+}
+
+check_formatting_config "clangFormat.extensions" "c,h,m,mm,cpp,cxx,hpp,," 0
----------------
mordante wrote:

```suggestion
check_formatting_config "clangFormat.extensions" "c,h,m,mm,cpp,cxx,hpp,inc," 0
```
The extension is used for modules and in under src. 

https://github.com/llvm/llvm-project/pull/73798