configure.py: add check header targets

Our guidelines dictate that each header is self-sufficient, i.e.
after including it into an empty .cc file, the .cc file can be compiled
without having to include any other header file.
Currently we don't have any tool to check that a header is self
sufficient. This patch aims to remedy that by adding a target to check
each header, as well as a target to check all the headers.
For each header a target is generated that does the equivalent of
including the header into an empty .cc file, then compiling the
resulting .cc file.This targetis called {header_name}.o, so for
given the header `myheader.hh` this will be `build/dev/myheader.hh.o`
(if the dev build-mode is used).
Also a target, `checkheaders` is added which validates all headers in
the project. This currently fails as we have many headers that are not
self-sufficient.

Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <fdf550dc71203417252f1d8144e7a540eec074a1.1552636812.git.bdenes@scylladb.com>

configure.py

@@ -215,6 +215,28 @@ class Antlr3Grammar(object):
         return self.source.endswith(end)
 
 
+def find_headers(repodir, excluded_dirs):
+    walker = os.walk(repodir)
+
+    _, dirs, files = next(walker)
+    for excl_dir in excluded_dirs:
+        try:
+            dirs.remove(excl_dir)
+        except ValueError:
+            # Ignore complaints about excl_dir not being in dirs
+            pass
+
+    is_hh = lambda f: f.endswith('.hh')
+    headers = list(filter(is_hh, files))
+
+    for dirpath, _, files in walker:
+        if dirpath.startswith('./'):
+            dirpath = dirpath[2:]
+        headers += [os.path.join(dirpath, hh) for hh in filter(is_hh, files)]
+
+    return headers
+
+
 modes = {
     'debug': {
         'sanitize': '-fsanitize=address -fsanitize=leak -fsanitize=undefined',
@@ -768,6 +790,8 @@ idls = ['idl/gossip_digest.idl.hh',
         'idl/view.idl.hh',
         ]
 
+headers = find_headers('.', excluded_dirs=['idl', 'build', 'seastar', '.git'])
+
 scylla_tests_dependencies = scylla_core + idls + [
     'tests/cql_test_env.cc',
     'tests/cql_assertions.cc',
@@ -1187,6 +1211,10 @@ with open(buildfile, 'w') as f:
                             s/exceptions::syntax_exception e/exceptions::syntax_exception\& e/' $
                         build/{mode}/gen/${{stem}}Parser.cpp
                 description = ANTLR3 $in
+            rule checkhh.{mode}
+              command = $cxx -MD -MT $out -MF $out.d {sanitize} {seastar_cflags} $cxxflags $cxxflags_{mode} $obj_cxxflags -x c++ --include=$in -c -o $out /dev/null
+              description = CHECKHH $in
+              depfile = $out.d
             ''').format(mode=mode, antlr3_exec=antlr3_exec, fmt_lib=fmt_lib, **modeval))
         f.write(
             'build {mode}: phony {artifacts}\n'.format(
@@ -1273,16 +1301,19 @@ with open(buildfile, 'w') as f:
             )
         )
 
+
+        gen_headers = []
+        for th in thrifts:
+            gen_headers += th.headers('$builddir/{}/gen'.format(mode))
+        for g in antlr3_grammars:
+            gen_headers += g.headers('$builddir/{}/gen'.format(mode))
+        gen_headers += list(swaggers.keys())
+        gen_headers += list(serializers.keys())
+        gen_headers_dep = ' '.join(gen_headers)
+
         for obj in compiles:
             src = compiles[obj]
-            gen_headers = []
-            for th in thrifts:
-                gen_headers += th.headers('$builddir/{}/gen'.format(mode))
-            for g in antlr3_grammars:
-                gen_headers += g.headers('$builddir/{}/gen'.format(mode))
-            gen_headers += list(swaggers.keys())
-            gen_headers += list(serializers.keys())
-            f.write('build {}: cxx.{} {} || {} {}\n'.format(obj, mode, src, seastar_dep, ' '.join(gen_headers)))
+            f.write('build {}: cxx.{} {} || {} {}\n'.format(obj, mode, src, seastar_dep, gen_headers_dep))
             if src in extra_cxxflags:
                 f.write('    cxxflags = {seastar_cflags} $cxxflags $cxxflags_{mode} {extra_cxxflags}\n'.format(mode=mode, extra_cxxflags=extra_cxxflags[src], **modeval))
         for hh in swaggers:
@@ -1307,6 +1338,10 @@ with open(buildfile, 'w') as f:
                 if cc.endswith('Parser.cpp') and has_sanitize_address_use_after_scope:
                     # Parsers end up using huge amounts of stack space and overflowing their stack
                     f.write('  obj_cxxflags = -fno-sanitize-address-use-after-scope\n')
+        for hh in headers:
+            f.write('build $builddir/{mode}/{hh}.o: checkhh.{mode} {hh} || {gen_headers_dep}\n'.format(
+                    mode=mode, hh=hh, gen_headers_dep=gen_headers_dep))
+
         f.write('build seastar/build/{mode}/libseastar.a seastar/build/{mode}/apps/iotune/iotune: ninja | always\n'
                 .format(**locals()))
         f.write('  pool = seastar_pool\n')
@@ -1321,6 +1356,9 @@ with open(buildfile, 'w') as f:
         f.write('    command = make -C libdeflate BUILD_DIR=../build/{mode}/libdeflate/ CFLAGS="{libdeflate_cflags}" CC={args.cc} ../build/{mode}/libdeflate//libdeflate.a\n'.format(**locals()))
         f.write('build build/{mode}/libdeflate/libdeflate.a: libdeflate.{mode}\n'.format(**locals()))
 
+    mode = 'dev' if 'dev' in modes else modes[0]
+    f.write('build checkheaders: phony || {}\n'.format(' '.join(['$builddir/{}/{}.o'.format(mode, hh) for hh in headers])))
+
     f.write(textwrap.dedent('''\
         rule configure
           command = {python} configure.py $configure_args