Revert "scripts: gcc-wrapper: Use wrapper to check compiler warnings"

gcc-wrapper simulates building with -Werror, but with a few hardcoded
file:line combinations that don't get promoted to errors.

We're already building with -Werror anyway without issue, so this script
is redundant and just adds a dependency on Python 2.

This reverts commit ca2dc1f081b0a15d28b5b0d3f032b89aa819b65c.

Change-Id: Id4a75ff16fb75e7d621c532a37ddcbe0efa01040
Signed-off-by: Greg Hackmann <ghackmann@google.com>

Makefile

@@ -385,7 +385,7 @@ READELF		= llvm-readelf
 OBJSIZE		= llvm-size
 STRIP		= llvm-strip
 else
-REAL_CC		= $(CROSS_COMPILE)gcc
+CC		= $(CROSS_COMPILE)gcc
 LD		= $(CROSS_COMPILE)ld
 AR		= $(CROSS_COMPILE)ar
 NM		= $(CROSS_COMPILE)nm
@@ -407,10 +407,6 @@ PYTHON2		= python2
 PYTHON3		= python3
 CHECK		= sparse
 
-# Use the wrapper for the compiler.  This wrapper scans for new
-# warnings and causes the build to stop upon encountering them
-CC		= $(PYTHON) $(srctree)/scripts/gcc-wrapper.py $(REAL_CC)
-
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
 		  -Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
 NOSTDINC_FLAGS  =

scripts/gcc-wrapper.py

@@ -1,75 +0,0 @@
-#! /usr/bin/env python2
-# SPDX-License-Identifier: GPL-2.0-only
-# Copyright (c) 2011-2017, 2018 The Linux Foundation. All rights reserved.
-
-# -*- coding: utf-8 -*-
-
-# Invoke gcc, looking for warnings, and causing a failure if there are
-# non-whitelisted warnings.
-
-import errno
-import re
-import os
-import sys
-import subprocess
-
-# Note that gcc uses unicode, which may depend on the locale.  TODO:
-# force LANG to be set to en_US.UTF-8 to get consistent warnings.
-
-allowed_warnings = set([
-    "umid.c:138",
-    "umid.c:213",
-    "umid.c:388",
- ])
-
-# Capture the name of the object file, can find it.
-ofile = None
-
-warning_re = re.compile(r'''(.*/|)([^/]+\.[a-z]+:\d+):(\d+:)? warning:''')
-def interpret_warning(line):
-    """Decode the message from gcc.  The messages we care about have a filename, and a warning"""
-    line = line.rstrip('\n')
-    m = warning_re.match(line)
-    if m and m.group(2) not in allowed_warnings:
-        print "error, forbidden warning:", m.group(2)
-
-        # If there is a warning, remove any object if it exists.
-        if ofile:
-            try:
-                os.remove(ofile)
-            except OSError:
-                pass
-        sys.exit(1)
-
-def run_gcc():
-    args = sys.argv[1:]
-    # Look for -o
-    try:
-        i = args.index('-o')
-        global ofile
-        ofile = args[i+1]
-    except (ValueError, IndexError):
-        pass
-
-    compiler = sys.argv[0]
-
-    try:
-        proc = subprocess.Popen(args, stderr=subprocess.PIPE)
-        for line in proc.stderr:
-            print line,
-            interpret_warning(line)
-
-        result = proc.wait()
-    except OSError as e:
-        result = e.errno
-        if result == errno.ENOENT:
-            print args[0] + ':',e.strerror
-            print 'Is your PATH set correctly?'
-        else:
-            print ' '.join(args), str(e)
-
-    return result
-
-if __name__ == '__main__':
-    status = run_gcc()
-    sys.exit(status)