Update .clang-tidy, Makefile, and documentation for improved code quality checks

- Simplified .clang-tidy configuration to enforce one variable per declaration for better readability.
- Updated Makefile to automatically find and use clang-format and clang-tidy from Homebrew's LLVM installation.
- Enhanced CONTRIBUTING.md to clarify installation instructions for clang tools and added guidelines for variable declarations.
- Refactored multiple C files to declare one variable per line, improving code readability.

Author: ohkimur

.clang-tidy

@@ -1,21 +1,10 @@
 ---
+# Minimal checks for K&R C code style
+# Only enforce one variable per declaration for readability 
 Checks: >
   -*,
-  bugprone-*,
-  cert-*,
-  clang-analyzer-*,
-  cppcoreguidelines-*,
-  performance-*,
-  portability-*,
-  readability-*,
-  -readability-magic-numbers,
-  -readability-identifier-length,
-  -cppcoreguidelines-avoid-magic-numbers,
-  -bugprone-easily-swappable-parameters,
-  -readability-function-cognitive-complexity
+  readability-isolate-declaration
 
 WarningsAsErrors: ''
 HeaderFilterRegex: '.*'
-AnalyzeTemporaryDtors: false
 FormatStyle: 'file'
-User: ''

.github/workflows/c.yml

@@ -12,6 +12,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Install clang-tidy
+        run: sudo apt-get update && sudo apt-get install -y clang-tidy
+
       - name: Check formatting
         run: make format-check
 

CONTRIBUTING.md

@@ -15,19 +15,20 @@ Thanks for your interest in contributing! This guide will help you get started.
 
 You'll need:
 - A C compiler (GCC or Clang)
-- `clang-format` for code formatting
 - `make` for building
+- `clang-format` and `clang-tidy` for code quality checks
 
-### Installing clang-format
+### Installing Dependencies
 
 **macOS:**
 ```shell
-brew install clang-format
+brew install llvm
 ```
+> The Makefile automatically finds the tools from Homebrew's LLVM installation - no need to modify your PATH.
 
 **Ubuntu / Debian:**
 ```shell
-sudo apt-get install clang-format
+sudo apt-get install clang-format clang-tidy
 ```
 
 **Arch Linux:**
@@ -69,6 +70,25 @@ The CI will automatically check formatting and linting on your pull request.
 
 We use `clang-format` with minimal configuration (LLVM style, 4-space indentation). Just run `make format` and your code will be properly formatted.
 
+Additional rules enforced by `clang-tidy`:
+
+### One variable per declaration
+
+Declare each variable on its own line for better readability.
+
+```c
+// ✗ Avoid
+int x, y, z;
+float fahr, celsius;
+
+// ✓ Preferred
+int x;
+int y;
+int z;
+float fahr;
+float celsius;
+```
+
 ## What to Contribute
 
 - **Bug fixes** - Found an error in a solution? Please fix it!

Makefile

@@ -6,20 +6,39 @@ EXECS = $(SOURCES:%.c=%)
 LDLIBS = -lm
 CFLAGS = -Wall -Wextra -Wpedantic
 
+# Find clang tools: check PATH first, then Homebrew LLVM location
+LLVM_PREFIX := $(shell brew --prefix llvm 2>/dev/null)
+CLANG_FORMAT := $(or $(shell command -v clang-format 2>/dev/null),$(wildcard $(LLVM_PREFIX)/bin/clang-format))
+CLANG_TIDY := $(or $(shell command -v clang-tidy 2>/dev/null),$(wildcard $(LLVM_PREFIX)/bin/clang-tidy))
+
 all: install-hooks $(EXECS)
 
 lint:
 	@echo "Linting with compiler warnings..."
 	@for f in $(filter %.c, $(SOURCES)); do \
 		$(CC) $(CFLAGS) -fsyntax-only $$f 2>&1 || exit 1; \
 	done
+ifneq ($(CLANG_TIDY),)
+	@echo "Running clang-tidy..."
+	@for f in $(filter %.c, $(SOURCES)); do \
+		$(CLANG_TIDY) $$f -- $(CFLAGS) 2>&1 || exit 1; \
+	done
+else
+	@echo "Skipping clang-tidy (not installed). Install with: brew install llvm"
+endif
 	@echo "Lint passed!"
 
 format:
-	find . \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 clang-format -i
+ifeq ($(CLANG_FORMAT),)
+	$(error clang-format not found. Install with: brew install llvm)
+endif
+	find . \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 $(CLANG_FORMAT) -i
 
 format-check:
-	find . \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 clang-format --dry-run --Werror
+ifeq ($(CLANG_FORMAT),)
+	$(error clang-format not found. Install with: brew install llvm)
+endif
+	find . \( -name '*.c' -o -name '*.h' \) -print0 | xargs -0 $(CLANG_FORMAT) --dry-run --Werror
 
 check: format-check lint
 

chapter_1/exercise_1_03/fahrenheit_celsius.c

@@ -5,8 +5,11 @@
 // floating point version
 
 int main(void) {
-    float fahr, celsius;
-    int lower, upper, step;
+    float fahr;
+    float celsius;
+    int lower;
+    int upper;
+    int step;
 
     lower = 0;
     upper = 300;

chapter_1/exercise_1_04/celsius_fahrenheit.c

@@ -5,8 +5,11 @@
 // floating point version
 
 int main(void) {
-    float celsius, fahr;
-    int lower, upper, step;
+    float celsius;
+    float fahr;
+    int lower;
+    int upper;
+    int step;
 
     lower = 0;
     upper = 300;

chapter_1/exercise_1_05/celsius_fahrenheit.c

@@ -5,8 +5,11 @@
 // floating point version with for loop
 
 int main(void) {
-    float celsius, fahr;
-    int lower, upper, step;
+    float celsius;
+    float fahr;
+    int lower;
+    int upper;
+    int step;
 
     lower = 0;
     upper = 300;

chapter_1/exercise_1_15/temperature_conversion.c

@@ -3,8 +3,11 @@
 float celsius_to_fahrenheit(int celsius);
 
 int main(void) {
-    float celsius, fahr;
-    int lower, upper, step;
+    float celsius;
+    float fahr;
+    int lower;
+    int upper;
+    int step;
 
     lower = 0;
     upper = 300;

chapter_1/exercise_1_16/longest_line.c

@@ -30,7 +30,8 @@ int main(void) {
 }
 
 int get_line(char line[], int maxline) {
-    int c, i;
+    int c;
+    int i;
 
     for (i = 0; i < maxline - 1 && (c = getchar()) != EOF && c != '\n'; ++i) {
         line[i] = c;

chapter_1/exercise_1_17/line_80.c

@@ -19,7 +19,8 @@ int main(void) {
 }
 
 int get_line(char line[], int max_line_len) {
-    int c, i;
+    int c;
+    int i;
 
     for (i = 0; i < max_line_len - 1 && (c = getchar()) != EOF && c != '\n';
          ++i) {