[pygobject] setup.py: Add default compiler warnings like with autotools

[Christoph Reiter <creiter src gnome org>]

commit f3864132405bf5124db77e6dc9fbccfc52dea7b1
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Fri Mar 16 11:08:15 2018 +0100

    setup.py: Add default compiler warnings like with autotools
    
    With clang we could pass a flag to ignore unknown warning flags but
    gcc errors out so we have to check if each flag is supported.
    Turns out we can do this reasonably fast if we try to remove the
    flags mentioned in stderr first.

 setup.py | 128 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 123 insertions(+), 5 deletions(-)
---
diff --git a/setup.py b/setup.py
index 1620c4a7..aa4cfc66 100755
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,7 @@ from setuptools import setup, find_packages
 from distutils.core import Extension, Distribution, Command
 from distutils.errors import DistutilsSetupError, DistutilsOptionError
 from distutils.ccompiler import new_compiler
-from distutils.sysconfig import get_python_lib
+from distutils.sysconfig import get_python_lib, customize_compiler
 from distutils import dir_util, log
 
 
@@ -139,6 +139,59 @@ def pkg_config_parse(opt, pkg):
     return [x.lstrip(opt) for x in output.split()]
 
 
+def filter_compiler_arguments(compiler, args):
+    """Given a compiler instance and a list of compiler warning flags
+    returns the list of supported flags.
+    """
+
+    if compiler.compiler_type == "msvc":
+        # TODO
+        return []
+
+    extra = []
+
+    def check_arguments(compiler, args):
+        p = subprocess.Popen(
+            [compiler.compiler[0]] + args + extra + ["-x", "c", "-E", "-"],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+        stdout, stderr = p.communicate(b"int i;\n")
+        if p.returncode != 0:
+            text = stderr.decode("ascii", "replace")
+            return False, [a for a in args if a in text]
+        else:
+            return True, []
+
+    def check_argument(compiler, arg):
+        return check_arguments(compiler, [arg])[0]
+
+    # clang doesn't error out for unknown options, force it to
+    if check_argument(compiler, '-Werror=unknown-warning-option'):
+        extra += ['-Werror=unknown-warning-option']
+    if check_argument(compiler, '-Werror=unused-command-line-argument'):
+        extra += ['-Werror=unused-command-line-argument']
+
+    # first try to remove all arguments contained in the error message
+    supported = list(args)
+    while 1:
+        ok, maybe_unknown = check_arguments(compiler, supported)
+        if ok:
+            return supported
+        elif not maybe_unknown:
+            break
+        for unknown in maybe_unknown:
+            if not check_argument(compiler, unknown):
+                supported.remove(unknown)
+
+    # hm, didn't work, try each argument one by one
+    supported = []
+    for arg in args:
+        if check_argument(compiler, arg):
+            supported.append(arg)
+    return supported
+
+
 du_sdist = get_command_class("sdist")
 
 
@@ -247,9 +300,6 @@ class build_tests(Command):
         cmd.ensure_finalized()
         cmd.run()
 
-        from distutils.ccompiler import new_compiler
-        from distutils.sysconfig import customize_compiler
-
         gidatadir = pkg_config_parse(
             "--variable=gidatadir", "gobject-introspection-1.0")[0]
         g_ir_scanner = pkg_config_parse(
@@ -432,10 +482,12 @@ class build_tests(Command):
         add_ext_pkg_config_dep(ext, compiler.compiler_type, "glib-2.0")
         add_ext_pkg_config_dep(ext, compiler.compiler_type, "gio-2.0")
         add_ext_pkg_config_dep(ext, compiler.compiler_type, "cairo")
+        add_ext_warn_flags(ext, compiler)
 
         dist = Distribution({"ext_modules": [ext]})
         cmd = dist.get_command_obj("build_ext")
         cmd.inplace = True
+        cmd.force = self.force
         cmd.ensure_finalized()
         cmd.run()
 
@@ -656,6 +708,67 @@ def add_ext_pkg_config_dep(ext, compiler_type, name):
         ext.libraries += pkg_config_parse("--libs-only-l", name)
 
 
+def add_ext_warn_flags(ext, compiler, _cache={}):
+    cache_key = compiler.compiler[0]
+    if cache_key not in _cache:
+
+        args = [
+            "-Wall",
+            "-Warray-bounds",
+            # "-Wcast-align",
+            # "-Wdeclaration-after-statement",
+            # "-Wdouble-promotion",
+            "-Wduplicated-branches",
+            # "-Wduplicated-cond",
+            "-Wextra",
+            "-Wformat=2",
+            "-Wformat-nonliteral",
+            "-Wformat-security",
+            "-Wimplicit-function-declaration",
+            "-Winit-self",
+            "-Winline",
+            # "-Wjump-misses-init",
+            # "-Wlogical-op",
+            "-Wmissing-declarations",
+            "-Wmissing-format-attribute",
+            "-Wmissing-include-dirs",
+            "-Wmissing-noreturn",
+            "-Wmissing-prototypes",
+            "-Wnested-externs",
+            # "-Wnull-dereference",
+            "-Wold-style-definition",
+            "-Wpacked",
+            "-Wpointer-arith",
+            "-Wredundant-decls",
+            "-Wrestrict",
+            "-Wreturn-type",
+            "-Wshadow",
+            "-Wsign-compare",
+            "-Wstrict-aliasing",
+            "-Wstrict-prototypes",
+            "-Wswitch-default",
+            "-Wundef",
+            "-Wunused-but-set-variable",
+            "-Wwrite-strings",
+        ]
+
+        args += [
+            "-Wno-incompatible-pointer-types-discards-qualifiers",
+            "-Wno-missing-field-initializers",
+            "-Wno-unused-parameter",
+            "-Wno-discarded-qualifiers",
+        ]
+
+        # silence clang for unused gcc CFLAGS added by Debian
+        args += [
+            "-Wno-unused-command-line-argument",
+        ]
+
+        _cache[cache_key] = filter_compiler_arguments(compiler, args)
+
+    ext.extra_compile_args += _cache[cache_key]
+
+
 du_build_ext = get_command_class("build_ext")
 
 
@@ -690,8 +803,11 @@ class build_ext(du_build_ext):
     def _setup_extensions(self):
         ext = {e.name: e for e in self.extensions}
 
+        compiler = new_compiler(compiler=self.compiler)
+        customize_compiler(compiler)
+
         def add_dependency(ext, name):
-            add_ext_pkg_config_dep(ext, self.compiler_type, name)
+            add_ext_pkg_config_dep(ext, compiler.compiler_type, name)
 
         def add_pycairo(ext):
             ext.include_dirs += [get_pycairo_include_dir()]
@@ -701,6 +817,7 @@ class build_ext(du_build_ext):
         add_dependency(gi_ext, "gio-2.0")
         add_dependency(gi_ext, "gobject-introspection-1.0")
         add_dependency(gi_ext, "libffi")
+        add_ext_warn_flags(gi_ext, compiler)
 
         gi_cairo_ext = ext["gi._gi_cairo"]
         add_dependency(gi_cairo_ext, "glib-2.0")
@@ -710,6 +827,7 @@ class build_ext(du_build_ext):
         add_dependency(gi_cairo_ext, "cairo")
         add_dependency(gi_cairo_ext, "cairo-gobject")
         add_pycairo(gi_cairo_ext)
+        add_ext_warn_flags(gi_cairo_ext, compiler)
 
     def run(self):
         self._write_config_h()