Fix the issue with using available clang-format version in format

.github/workflows/format.yml

@@ -74,4 +74,4 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Run formatter
-        run: ./bin/format --check ./pennylane_lightning/src
+        run: ./bin/format --check --cfversion 12 ./pennylane_lightning/src

Makefile

@@ -19,7 +19,8 @@ help:
 	@echo "  test-cpp           to run the C++ test suite"
 	@echo "  test-python        to run the Python test suite"
 	@echo "  coverage           to generate a coverage report"
-	@echo "  format [check=1]   to apply C++ formatter; use with 'check=1' to check instead of modify (requires clang-format)"
+	@echo "  format [check=1]   to apply C++ and Python formatter; use with 'check=1' to check instead of modify (requires black and clang-format)"
+	@echo "  format [version=?] to apply C++ and Python formatter; use with 'version={version}' to check or modify with clang-format-{version} instead of clang-format"
 	@echo "  check-tidy         to build PennyLane-Lightning with ENABLE_CLANG_TIDY=ON (requires clang-tidy & CMake)"
 
 .PHONY: install
@@ -109,9 +110,9 @@ format: format-cpp format-python
 
 format-cpp:
 ifdef check
-	./bin/format --check ./pennylane_lightning/src
+	./bin/format --check --cfversion $(if $(version:-=),$(version),0) ./pennylane_lightning/src
 else
-	./bin/format ./pennylane_lightning/src
+	./bin/format --cfversion $(if $(version:-=),$(version),0) ./pennylane_lightning/src
 endif
 
 format-python:

bin/format

@@ -20,36 +20,28 @@ IGNORE_PATTERNS = ["external"]
 
 DEFAULT_CLANG_FORMAT_VERSION=12
 
-BASE_ARGS = [f"-style={json.dumps(CLANG_FMT_STYLE_CFG)}"]
-
+BASE_ARGS = f"-style={json.dumps(CLANG_FMT_STYLE_CFG)}"
 
 def parse_version(version_string):
     version_rgx = "version (\d+)"
 
     m = re.search(version_rgx, version_string)
     return int(m.group(1))
 
-def clang_format_command():
-    command = f"clang-format-{DEFAULT_CLANG_FORMAT_VERSION}"
-
-    if shutil.which(command) is None:
-        print(f"{command} is not found. Find default clang-format instead.")
-        command = "clang-format"
-        if shutil.which(command) is None:
-            print(f"Default clang-format is not found.")
-            raise FileNotFoundError("clang-format is not installed or is not in PATH.")
-        else:
-            p = subprocess.run([command, "--version"], stdout=subprocess.PIPE,
-                    stderr=subprocess.STDOUT, universal_newlines=True)
-            version = parse_version(p.stdout)
-
-            if version < DEFAULT_CLANG_FORMAT_VERSION:
-                print(f"Using clang-format version {version}. \
-                        As this is lower than the version used for the CI, \
-                        the CI may fail even after formatting.")
-
-    return command
-
+def check_bin(command):
+    try:
+        p = subprocess.run([command, "--version"], 
+        stdout=subprocess.PIPE, stderr=subprocess.STDOUT, universal_newlines=True)
+        version = parse_version(p.stdout)
+
+        if version < DEFAULT_CLANG_FORMAT_VERSION:
+            print(f"Using clang-format version {version}. \
+                    As this is lower than the version used for the CI, \
+                    the CI may fail even after formatting.")
+    except FileNotFoundError as exc:
+        raise FileNotFoundError(
+            f"{command} is not installed or is not in PATH."
+        ) from exc
 
 def parse_args():
     parser = argparse.ArgumentParser(
@@ -71,14 +63,21 @@ def parse_args():
         action="store_true",
         help="print detailed information about format violations",
     )
-
+    parser.add_argument(
+        "-f",
+        "--cfversion",
+        type=int,
+        default=0,
+        action="store",
+        help="set a version number for clang-format",
+    )
     return parser.parse_args()
 
-def fmt(command, paths) -> int:
-    files = get_cpp_files(paths)
-    cmd = (command, *BASE_ARGS, "-i", *files)
+def fmt(args, command) -> int:
+    files = get_cpp_files(args.paths)
+    cmd = (command, BASE_ARGS, "-i", *files)
 
-    sys.stderr.write(f"Formatting {len(files)} files in {paths}.\n")
+    sys.stderr.write(f"Formatting {len(files)} files in {args.paths}.\n")
 
     ret = subprocess.run(cmd, capture_output=True, universal_newlines=True)
     if ret.returncode != 0:
@@ -88,11 +87,11 @@ def fmt(command, paths) -> int:
     return 0
 
 
-def check(command, paths, is_verbose) -> int:
-    cmd = (command, *BASE_ARGS, "--dry-run", "-Werror")
+def check(args, command) -> int:
+    cmd = (command, BASE_ARGS, "--dry-run", "-Werror")
 
     needs_reformatted_ct = 0
-    files = get_cpp_files(paths)
+    files = get_cpp_files(args.paths)
 
     for src_file in files:
         ret = subprocess.run(
@@ -101,7 +100,7 @@ def check(command, paths, is_verbose) -> int:
 
         if ret.returncode != 0:
             sys.stderr.write(f"Error: {src_file} would be reformatted.\n")
-            if is_verbose:
+            if args.verbose:
                 sys.stderr.write(ret.stderr)
 
             needs_reformatted_ct += 1
@@ -112,12 +111,19 @@ def check(command, paths, is_verbose) -> int:
     return needs_reformatted_ct
 
 if __name__ == "__main__":
-    command = clang_format_command()
     args = parse_args()
 
+    cf_version = args.cfversion
+    cf_cmd = "clang-format"
+
+    if cf_version:
+        cf_cmd += f"-{cf_version}"
+
+    check_bin(cf_cmd)
+
     if args.check:
-        ret = check(command, args.paths, args.verbose)
+        ret = check(args, cf_cmd)
     else:
-        ret = fmt(command, args.paths)
+        ret = fmt(args, cf_cmd)
 
     sys.exit(int(ret > 0))

pennylane_lightning/_version.py

@@ -16,4 +16,4 @@
    Version number (major.minor.patch[-label])
 """
 
-__version__ = "0.24.0-dev2"
+__version__ = "0.24.0-dev3"