build: add formatting targets for c and lua files (#19488)

The targets will only format files that have been changed in current
branch compared to the master branch. This includes unstaged, staged and
committed files.

Add following make and cmake targets:
formatc   - format changed c files
formatlua - format changed lua files
format    - run formatc and formatlua

Remove scripts/uncrustify.sh as this deprecates it.

6 files changed, 95 insertions, 15 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6c54e5749b..caf9658699 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -675,6 +675,19 @@ add_dependencies(lintcommit nvim)
 add_custom_target(lint)
 add_dependencies(lint check-single-includes lintc lintlua lintpy lintsh lintcommit lintuncrustify)
 
+#
+# Format
+#
+add_custom_target(formatlua
+  COMMAND ${CMAKE_COMMAND}
+    -D FORMAT_PRG=${STYLUA_PRG}
+    -D LANG=lua
+    -P ${PROJECT_SOURCE_DIR}/cmake/Format.cmake
+  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+
+add_custom_target(format)
+add_dependencies(format formatc formatlua)
+
 install_helper(
   FILES ${CMAKE_SOURCE_DIR}/src/man/nvim.1
   DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
@@ -797,4 +810,3 @@ add_custom_target(uninstall
 if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
   add_subdirectory(cmake.packaging)
 endif()
-
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e26d0d63c5..17622fa33a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -218,6 +218,11 @@ You can lint a single file (but this will _not_ exclude legacy errors):
 
 ### Style
 
+- You can format files by using:
+```
+  make format
+```
+This will format changed Lua and C files with all appropriate flags set.
 - Style rules are (mostly) defined by `src/uncrustify.cfg` which tries to match
   the [style-guide]. To use the Nvim `gq` command with `uncrustify`:
   ```
diff --git a/Makefile b/Makefile
index e9a59f0941..c071338435 100644
--- a/Makefile
+++ b/Makefile
@@ -137,7 +137,7 @@ helphtml: | nvim build/runtime/doc/tags
 functionaltest functionaltest-lua unittest benchmark: | nvim
 	$(BUILD_TOOL) -C build $@
 
-lintlua lintsh lintpy lintuncrustify lintc lintcfull check-single-includes generated-sources lintcommit lint: | build/.ran-cmake
+lintlua lintsh lintpy lintuncrustify lintc lintcfull check-single-includes generated-sources lintcommit lint formatc formatlua format: | build/.ran-cmake
 	$(CMAKE_PRG) --build build --target $@
 
 test: functionaltest unittest
@@ -174,4 +174,4 @@ $(DEPS_BUILD_DIR)/%: phony_force
 	$(BUILD_TOOL) -C $(DEPS_BUILD_DIR) $(patsubst $(DEPS_BUILD_DIR)/%,%,$@)
 endif
 
-.PHONY: test lintlua lintpy lintsh functionaltest unittest lint lintc clean distclean nvim libnvim cmake deps install appimage checkprefix lintcommit
+.PHONY: test lintlua lintpy lintsh functionaltest unittest lint lintc clean distclean nvim libnvim cmake deps install appimage checkprefix lintcommit formatc formatlua format
diff --git a/cmake/Format.cmake b/cmake/Format.cmake
new file mode 100644
index 0000000000..4115e66705
--- /dev/null
+++ b/cmake/Format.cmake
@@ -0,0 +1,67 @@
+# Returns a list of all files that has been changed in current branch compared
+# to master branch. This includes unstaged, staged and committed files.
+function(get_changed_files outvar)
+  set(default_branch master)
+
+  execute_process(
+    COMMAND git branch --show-current
+    OUTPUT_VARIABLE current_branch
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+  execute_process(
+    COMMAND git merge-base ${default_branch} ${current_branch}
+    OUTPUT_VARIABLE ancestor_commit
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+  # Changed files that have been committed
+  execute_process(
+    COMMAND git diff --name-only ${ancestor_commit}...${current_branch}
+    OUTPUT_VARIABLE committed_files
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  separate_arguments(committed_files NATIVE_COMMAND ${committed_files})
+
+  # Unstaged files
+  execute_process(
+    COMMAND git diff --name-only
+    OUTPUT_VARIABLE unstaged_files
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  separate_arguments(unstaged_files NATIVE_COMMAND ${unstaged_files})
+
+  # Staged files
+  execute_process(
+    COMMAND git diff --cached --name-only
+    OUTPUT_VARIABLE staged_files
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  separate_arguments(staged_files NATIVE_COMMAND ${staged_files})
+
+  set(files ${committed_files} ${unstaged_files} ${staged_files})
+  list(REMOVE_DUPLICATES files)
+
+  set(${outvar} "${files}" PARENT_SCOPE)
+endfunction()
+
+get_changed_files(changed_files)
+
+if(LANG STREQUAL c)
+  list(FILTER changed_files INCLUDE REGEX "\\.[ch]$")
+  list(FILTER changed_files INCLUDE REGEX "^src/nvim/")
+
+  if(changed_files)
+    if(FORMAT_PRG)
+      execute_process(COMMAND ${FORMAT_PRG} -c "src/uncrustify.cfg" --replace --no-backup ${changed_files})
+    else()
+      message(STATUS "Uncrustify not found. Skip formatting C files.")
+    endif()
+  endif()
+elseif(LANG STREQUAL lua)
+  list(FILTER changed_files INCLUDE REGEX "\\.lua$")
+  list(FILTER changed_files INCLUDE REGEX "^runtime/")
+
+  if(changed_files)
+    if(FORMAT_PRG)
+      execute_process(COMMAND ${FORMAT_PRG} ${changed_files})
+    else()
+      message(STATUS "Stylua not found. Skip formatting lua files.")
+    endif()
+  endif()
+endif()
diff --git a/scripts/uncrustify.sh b/scripts/uncrustify.sh
deleted file mode 100755
index ac5d542c29..0000000000
--- a/scripts/uncrustify.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-
-# Check that you have uncrustify
-hash uncrustify
-
-COMMITISH="${1:-master}"
-for file in $(git diff --diff-filter=d --name-only $COMMITISH | grep '\.[ch]$'); do
-    uncrustify -c src/uncrustify.cfg -l C --replace --no-backup "$file"
-done
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index f302f25ad6..017883a913 100755
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -778,9 +778,16 @@ add_glob_targets(
   FLAGS -c "${PROJECT_SOURCE_DIR}/src/uncrustify.cfg" -q --check
   FILES ${LINT_NVIM_SOURCES}
   )
-
 add_dependencies(lintuncrustify uncrustify-version)
 
+add_custom_target(formatc
+  COMMAND ${CMAKE_COMMAND}
+    -D FORMAT_PRG=${UNCRUSTIFY_PRG}
+    -D LANG=c
+    -P ${PROJECT_SOURCE_DIR}/cmake/Format.cmake
+  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
+add_dependencies(formatc uncrustify-version)
+
 add_custom_target(
   lintcfull
   COMMAND