SERVER-12166: Promote struct/class mismatch warning to error with GCC/Clang

SConstruct

@@ -80,6 +80,7 @@ else:
 nix = not windows
 
 # --- options ----
+use_clang = False
 
 options = {}
 
@@ -1049,6 +1050,9 @@ def doConfigure(myenv):
 
     myenv = conf.Finish()
 
+    global use_clang
+    use_clang = using_clang()
+
     # Figure out what our minimum windows version is. If the user has specified, then use
     # that. Otherwise, if they have explicitly selected between 32 bit or 64 bit, choose XP or
     # Vista respectively. Finally, if they haven't done either of these, try invoking the
@@ -1125,7 +1129,7 @@ def doConfigure(myenv):
         test_mutation = mutation
         if using_gcc():
             test_mutation = copy.deepcopy(mutation)
-            # GCC helpfully doesn't issue a diagnostic on unkown flags of the form -Wno-xxx
+            # GCC helpfully doesn't issue a diagnostic on unknown flags of the form -Wno-xxx
             # unless other diagnostics are triggered. That makes it tough to check for support
             # for -Wno-xxx. To work around, if we see that we are testing for a flag of the
             # form -Wno-xxx (but not -Wno-error=xxx), we also add -Wxxx to the flags. GCC does
@@ -1180,12 +1184,6 @@ def doConfigure(myenv):
         # libraries have such things.
         AddToCCFLAGSIfSupported(myenv, '-Wno-unused-private-field')
 
-        # Clang warns about struct/class tag mismatch, but most people think that that is not
-        # really an issue, see
-        # http://stackoverflow.com/questions/4866425/mixing-class-and-struct. We disable the
-        # warning so it doesn't become an error.
-        AddToCCFLAGSIfSupported(myenv, '-Wno-mismatched-tags')
-
         # Prevents warning about using deprecated features (such as auto_ptr in c++11)
         # Using -Wno-error=deprecated-declarations does not seem to work on some compilers,
         # including at least g++-4.6.
@@ -1691,6 +1689,7 @@ Export('module_sconscripts')
 Export("debugBuild optBuild")
 Export("enforce_glibc")
 Export("s3push")
+Export("use_clang")
 
 env.SConscript('src/SConscript', variant_dir='$BUILD_DIR', duplicate=False)
 env.SConscript('src/SConscript.client', variant_dir='$BUILD_DIR/client_build', duplicate=False)

src/mongo/db/geo/s2.h

@@ -0,0 +1,45 @@
+/**
+*    Copyright (C) 2008-2012 10gen Inc.
+*
+*    This program is free software: you can redistribute it and/or  modify
+*    it under the terms of the GNU Affero General Public License, version 3,
+*    as published by the Free Software Foundation.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU Affero General Public License for more details.
+*
+*    You should have received a copy of the GNU Affero General Public License
+*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+*    As a special exception, the copyright holders give permission to link the
+*    code of portions of this program with the OpenSSL library under certain
+*    conditions as described in each individual source file and distribute
+*    linked combinations including the program with the OpenSSL library. You
+*    must comply with the GNU Affero General Public License in all respects for
+*    all of the code used other than as permitted herein. If you modify file(s)
+*    with this exception, you may extend this exception to your version of the
+*    file(s), but you are not obligated to do so. If you do not wish to do so,
+*    delete this exception statement from your version. If you delete this
+*    exception statement from all source files in the program, then also delete
+*    it in the license file.
+*/
+
+#pragma once
+
+/*
+ * This file's purpose is to confine the suppression of the Clang warning for mismatched-tags (struct vs class)
+ * in only the s2.h file
+ */
+
+#ifdef __clang__
+#pragma GCC diagnostic ignored "-Wmismatched-tags"
+#endif
+
+#include "third_party/s2/s2.h"
+
+#ifdef __clang__
+#pragma GCC diagnostic pop
+#endif
+

src/mongo/db/geo/s2common.cpp

@@ -31,7 +31,7 @@
 #include "mongo/db/geo/geoconstants.h"
 #include "mongo/db/geo/geoparser.h"
 #include "mongo/db/geo/geoquery.h"
-#include "third_party/s2/s2.h"
+#include "mongo/db/geo/s2.h"
 #include "third_party/s2/s2cell.h"
 #include "third_party/s2/s2regioncoverer.h"
 

src/mongo/db/geo/s2common.h

@@ -28,7 +28,7 @@
 
 #include "mongo/db/geo/geoparser.h"
 #include "mongo/db/geo/geoconstants.h"
-#include "third_party/s2/s2.h"
+#include "mongo/db/geo/s2.h"
 #include "third_party/s2/s2regioncoverer.h"
 #include "third_party/s2/s2cell.h"
 #include "third_party/s2/s2polyline.h"

src/mongo/db/geo/shapes.h

@@ -33,7 +33,7 @@
 
 #include "mongo/base/owned_pointer_vector.h"
 #include "mongo/db/jsobj.h"
-#include "third_party/s2/s2.h"
+#include "mongo/db/geo/s2.h"
 #include "third_party/s2/s2cap.h"
 #include "third_party/s2/s2cell.h"
 #include "third_party/s2/s2latlng.h"

src/mongo/db/query/index_bounds_builder.cpp

@@ -36,7 +36,7 @@
 #include "mongo/db/query/indexability.h"
 #include "mongo/db/query/qlog.h"
 #include "mongo/util/mongoutils/str.h"
-#include "third_party/s2/s2.h"
+#include "mongo/db/geo/s2.h"
 #include "third_party/s2/s2cell.h"
 #include "third_party/s2/s2regioncoverer.h"
 

src/third_party/s2/SConscript

@@ -1,6 +1,6 @@
 # -*- mode: python -*-
 
-Import("env windows linux darwin solaris")
+Import("env windows linux darwin solaris use_clang")
 
 env = env.Clone()
 
@@ -14,6 +14,13 @@ env.SConscript( [
 env.Append(CCFLAGS=['-Isrc/third_party/s2'])
 env.Append(CCFLAGS=['-DDEBUG_MODE=false'])
 
+# Clang warns about struct/class tag mismatch, but as long as this is
+# not a problem on Windows, these mismatches can be ignored
+# http://stackoverflow.com/questions/4866425/mixing-class-and-struct. W
+# warning so it doesn't become an error.
+if use_clang:
+    env.Append(CCFLAGS=['-Wno-mismatched-tags'])
+
 env.StaticLibrary( "s2",
     [ 
 	"s1angle.cc",