From 63c1f3114c351c76848308d30d2d9c37a41a9165 Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Thu, 25 Oct 2018 12:06:26 +0200
Subject: gcc-check: clang-check compatible wrapper

Perform syntax-only checks using a compilation database as produced by
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON, similar to clang-check.
---
 gcc-check | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100755 gcc-check

diff --git a/gcc-check b/gcc-check
new file mode 100755
index 0000000..8a233cf
--- /dev/null
+++ b/gcc-check
@@ -0,0 +1,134 @@
+#!/usr/bin/env python3
+"""
+Analogous to clang-check, but for use with GCC. Intended use:
+
+    cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=1 $srcdir
+    gcc-check path/to/source1.c path/to/source2.c
+
+Like clang-check, you can also add extra compiler options:
+
+    gcc-check -extra-arg=-Wno-missing-prototypes path/to/source.c
+"""
+import argparse
+import json
+import os
+import shlex
+import subprocess
+import sys
+
+
+def llvm_abspath(path):
+    # Deliberately preserves ".." in path="../x" for LLVM compatibility.
+    return os.path.join(os.getcwd(), path)
+
+
+# Make paths absolute (simplifying "a/../b" to "b")
+#canonicalize_path = os.path.abspath
+canonicalize_path = os.path.realpath
+
+
+def locate_compilation_database(path):
+    path = llvm_abspath(path)
+    if not os.path.isdir(path):
+        path = os.path.dirname(path)
+    while True:
+        db_path = os.path.join(path, 'compile_commands.json')
+        if os.path.exists(db_path):
+            return db_path
+        if path == '/':
+            break
+        path = os.path.dirname(path)
+    print('Could not auto-detect compilation database', file=sys.stderr)
+
+
+class DbEntry(object):
+    def __init__(self, obj):
+        def readstr(key):
+            value = obj.get(key)
+            if type(value) != str:
+                raise RuntimeError('Key %s not found' % key)
+            return value
+        self.directory = readstr('directory')
+        self.file = readstr('file')
+        self.command = readstr('command')
+        self.filepath = canonicalize_path(self.file)
+
+    def __str__(self):
+        return '{"directory": %r, "command": %r, "file": %r}' % \
+            (self.directory, self.command, self.file)
+
+    def check(self, extra_arg_before=[], extra_arg=[]):
+        args = shlex.split(self.command)
+        is_cpp = args[0].endswith('++')
+        args[0] = ['gcc', 'g++'][is_cpp]
+        args += extra_arg_before
+        args = [arg for arg in args if self._filter_cc_arg(arg, is_cpp)]
+        args += extra_arg
+        args += ['-fsyntax-only']
+        #print("Command: is_cpp=%r %r" % (is_cpp, args), file=sys.stderr)
+        subprocess.run(args, cwd=self.directory)
+
+    def _filter_cc_arg(self, arg, is_cpp):
+        # List of Clang-specific options that are not supported by GCC.
+        # (as added by Wireshark)
+        common_args = [
+            '-Qunused-arguments',
+            '-Wheader-guard',
+            '-Wcomma',
+            '-Wshorten-64-to-32',
+            '-Weverything',
+            '-Wno-documentation-unknown-command',
+            '-Wno-reserved-id-macro',
+        ]
+        c_args = [
+        ]
+        cpp_args = [
+            '-Wextra-semi',
+        ]
+        return arg not in common_args + (cpp_args if not is_cpp else c_args)
+
+
+def parse_db(entries, db_path):
+    with open(db_path) as f:
+        arr = json.load(f)
+        if type(arr) != list:
+            raise RuntimeError('Parse Error: expected array')
+        for obj in arr:
+            entry = DbEntry(obj)
+            entries[entry.filepath] = entry
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument('-p', metavar='string', dest='build_path',
+                    help='Build path')
+parser.add_argument('-extra-arg', metavar='string', dest='extra_arg',
+                    action='append', default=[],
+                    help='Additional argument to append to the compiler command line')
+parser.add_argument('-extra-arg-before', metavar='string',
+                    dest='extra_arg_before',
+                    action='append', default=[],
+                    help='Additional argument to prepend to the compiler command line')
+parser.add_argument('sources', nargs='+')
+
+
+def main():
+    args = parser.parse_args()
+    sources = [canonicalize_path(path) for path in args.sources]
+    build_path = args.build_path
+    if not build_path or not os.path.exists(build_path):
+        build_path = llvm_abspath(args.sources[0])
+    db_path = locate_compilation_database(build_path)
+    db = {}
+    if db_path:
+        parse_db(db, db_path)
+    for source_path in sources:
+        entry = db.get(source_path)
+        if entry is None:
+            print('Skipping %s. Compile command not found.' % source_path,
+                  file=sys.stderr)
+            continue
+        entry.check(args.extra_arg_before, args.extra_arg)
+
+
+if __name__ == '__main__':
+    main()
-- 
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