Produce compile_commands.json.

1 files changed, 197 insertions, 0 deletions

diff --git a/build/compile_commands.py b/build/compile_commands.py
new file mode 100644
index 0000000000..161ac6061e
--- /dev/null
+++ b/build/compile_commands.py
@@ -0,0 +1,197 @@
+# 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=[]
+
+# Cribbed from Tool/cc.py and Tool/c++.py. It would be better if
+# we could obtain this from SCons.
+_CSuffixes = ['.c']
+if not SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CSuffixes.append('.C')
+
+_CXXSuffixes = ['.cpp', '.cc', '.cxx', '.c++', '.C++']
+if SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CXXSuffixes.append('.C')
+
+# 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(node, target, prev_ni):
+    """ Dummy decider to force alwasy 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 $TARGET')
+
+    components_by_suffix = itertools.chain(
+        itertools.product(_CSuffixes, [
+            (static_obj, SCons.Defaults.StaticObjectEmitter, '$CCCOM'),
+            (shared_obj, SCons.Defaults.SharedObjectEmitter, '$SHCCCOM'),
+        ]),
+        itertools.product(_CXXSuffixes, [
+            (static_obj, SCons.Defaults.StaticObjectEmitter, '$CXXCOM'),
+            (shared_obj, SCons.Defaults.SharedObjectEmitter, '$SHCXXCOM'),
+        ]),
+    )
+
+    for entry in components_by_suffix:
+        suffix = entry[0]
+        builder, base_emitter, command = entry[1]
+
+        # Assumes a dictionary emitter
+        emitter = builder.emitter[suffix]
+        builder.emitter[suffix] = SCons.Builder.ListEmitter(
+            [
+                emitter,
+                makeEmitCompilationDbEntry(command),
+            ]
+        )
+
+    env['BUILDERS']['__COMPILATIONDB_Entry'] = SCons.Builder.Builder(
+        action=SCons.Action.Action(CompilationDbEntryAction, None),
+    )
+
+    env['BUILDERS']['__COMPILATIONDB_Database'] = SCons.Builder.Builder(
+        action=SCons.Action.Action(WriteCompilationDb, "$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