update to use scons compile db tool

SConstruct

@@ -310,9 +310,10 @@ if selected_platform in platform_list:
     from SCons import __version__ as scons_raw_version
 
     scons_ver = env._get_major_minor_revision(scons_raw_version)
-    if scons_ver >= (3, 1, 1):
-        env.Tool("compilation_db", toolpath=["misc/scons"])
-        env.Alias("compiledb", env.CompilationDatabase("compile_commands.json"))
+
+    if scons_ver >= (4, 0, 0):
+        env.Tool("compilation_db")
+        env.Alias("compiledb", env.CompilationDatabase())
 
     if env["dev"]:
         env["verbose"] = True

misc/scons/compilation_db.py

@@ -1,177 +0,0 @@
-# Copyright 2015 MongoDB Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-import json
-import SCons
-import itertools
-
-# Implements the ability for SCons to emit a compilation database for the MongoDB project. See
-# http://clang.llvm.org/docs/JSONCompilationDatabase.html for details on what a compilation
-# database is, and why you might want one. The only user visible entry point here is
-# 'env.CompilationDatabase'. This method takes an optional 'target' to name the file that
-# should hold the compilation database, otherwise, the file defaults to compile_commands.json,
-# which is the name that most clang tools search for by default.
-
-# TODO: Is there a better way to do this than this global? Right now this exists so that the
-# emitter we add can record all of the things it emits, so that the scanner for the top level
-# compilation database can access the complete list, and also so that the writer has easy
-# access to write all of the files. But it seems clunky. How can the emitter and the scanner
-# communicate more gracefully?
-__COMPILATION_DB_ENTRIES = []
-
-# We make no effort to avoid rebuilding the entries. Someday, perhaps we could and even
-# integrate with the cache, but there doesn't seem to be much call for it.
-class __CompilationDbNode(SCons.Node.Python.Value):
-    def __init__(self, value):
-        SCons.Node.Python.Value.__init__(self, value)
-        self.Decider(changed_since_last_build_node)
-
-
-def changed_since_last_build_node(child, target, prev_ni, node):
-    """ Dummy decider to force always building"""
-    return True
-
-
-def makeEmitCompilationDbEntry(comstr):
-    """
-    Effectively this creates a lambda function to capture:
-    * command line
-    * source
-    * target
-    :param comstr: unevaluated command line
-    :return: an emitter which has captured the above
-    """
-    user_action = SCons.Action.Action(comstr)
-
-    def EmitCompilationDbEntry(target, source, env):
-        """
-        This emitter will be added to each c/c++ object build to capture the info needed
-        for clang tools
-        :param target: target node(s)
-        :param source: source node(s)
-        :param env: Environment for use building this node
-        :return: target(s), source(s)
-        """
-
-        dbtarget = __CompilationDbNode(source)
-
-        entry = env.__COMPILATIONDB_Entry(
-            target=dbtarget,
-            source=[],
-            __COMPILATIONDB_UTARGET=target,
-            __COMPILATIONDB_USOURCE=source,
-            __COMPILATIONDB_UACTION=user_action,
-            __COMPILATIONDB_ENV=env,
-        )
-
-        # TODO: Technically, these next two lines should not be required: it should be fine to
-        # cache the entries. However, they don't seem to update properly. Since they are quick
-        # to re-generate disable caching and sidestep this problem.
-        env.AlwaysBuild(entry)
-        env.NoCache(entry)
-
-        __COMPILATION_DB_ENTRIES.append(dbtarget)
-
-        return target, source
-
-    return EmitCompilationDbEntry
-
-
-def CompilationDbEntryAction(target, source, env, **kw):
-    """
-    Create a dictionary with evaluated command line, target, source
-    and store that info as an attribute on the target
-    (Which has been stored in __COMPILATION_DB_ENTRIES array
-    :param target: target node(s)
-    :param source: source node(s)
-    :param env: Environment for use building this node
-    :param kw:
-    :return: None
-    """
-
-    command = env["__COMPILATIONDB_UACTION"].strfunction(
-        target=env["__COMPILATIONDB_UTARGET"], source=env["__COMPILATIONDB_USOURCE"], env=env["__COMPILATIONDB_ENV"],
-    )
-
-    entry = {
-        "directory": env.Dir("#").abspath,
-        "command": command,
-        "file": str(env["__COMPILATIONDB_USOURCE"][0]),
-    }
-
-    target[0].write(entry)
-
-
-def WriteCompilationDb(target, source, env):
-    entries = []
-
-    for s in __COMPILATION_DB_ENTRIES:
-        entries.append(s.read())
-
-    with open(str(target[0]), "w") as target_file:
-        json.dump(entries, target_file, sort_keys=True, indent=4, separators=(",", ": "))
-
-
-def ScanCompilationDb(node, env, path):
-    return __COMPILATION_DB_ENTRIES
-
-
-def generate(env, **kwargs):
-
-    static_obj, shared_obj = SCons.Tool.createObjBuilders(env)
-
-    env["COMPILATIONDB_COMSTR"] = kwargs.get("COMPILATIONDB_COMSTR", "Building compilation database $TARGET")
-
-    components_by_suffix = itertools.chain(
-        itertools.product(
-            env["CPPSUFFIXES"],
-            [
-                (static_obj, SCons.Defaults.StaticObjectEmitter, "$CXXCOM"),
-                (shared_obj, SCons.Defaults.SharedObjectEmitter, "$SHCXXCOM"),
-            ],
-        ),
-    )
-
-    for entry in components_by_suffix:
-        suffix = entry[0]
-        builder, base_emitter, command = entry[1]
-
-        # Ensure we have a valid entry
-        # used to auto ignore header files
-        if suffix in builder.emitter:
-            emitter = builder.emitter[suffix]
-            builder.emitter[suffix] = SCons.Builder.ListEmitter([emitter, makeEmitCompilationDbEntry(command),])
-
-    env["BUILDERS"]["__COMPILATIONDB_Entry"] = SCons.Builder.Builder(
-        action=SCons.Action.Action(CompilationDbEntryAction, None),
-    )
-
-    env["BUILDERS"]["__COMPILATIONDB_Database"] = SCons.Builder.Builder(
-        action=SCons.Action.Action(WriteCompilationDb, "$COMPILATIONDB_COMSTR"),
-        target_scanner=SCons.Scanner.Scanner(function=ScanCompilationDb, node_class=None),
-    )
-
-    def CompilationDatabase(env, target):
-        result = env.__COMPILATIONDB_Database(target=target, source=[])
-
-        env.AlwaysBuild(result)
-        env.NoCache(result)
-
-        return result
-
-    env.AddMethod(CompilationDatabase, "CompilationDatabase")
-
-
-def exists(env):
-    return True