SERVER-55833 Add a tool to implement forced includes

1 files changed, 83 insertions, 0 deletions

diff --git a/site_scons/site_tools/forceincludes.py b/site_scons/site_tools/forceincludes.py
new file mode 100644
index 00000000000..7238a54f0e3
--- /dev/null
+++ b/site_scons/site_tools/forceincludes.py
@@ -0,0 +1,83 @@
+# Copyright 2021 MongoDB Inc.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+import SCons
+
+def _add_scanner(builder):
+    # We are taking over the target scanner here. If we want to not do
+    # that we need to invent a ListScanner concept to inject. What if
+    # the other scanner wants a different path_function?
+    assert builder.target_scanner is None
+
+    def new_scanner(node, env, path, argument):
+        # Use the path information that FindPathDirs gave us to resolve
+        # the forced includes into nodes given the search path.
+        fis = [env.FindFile(f, path) for f in env.get('FORCEINCLUDES', [])]
+
+        # Use the nodes *source* scanner, which was provided to us as
+        # `argument` when we created this scanner, to scan the forced
+        # includes for transitive includes.
+        node.get_executor().scan(scanner=argument, node_list=fis)
+
+        # The forced includes will be added as implicit dependencies
+        # for us when we return them.
+        return fis
+
+    # The 'builder.builder' here is because we need to reach inside
+    # the CompositeBuilder that wraps the object builders that come
+    # back from createObjBuilders.
+    builder.builder.target_scanner = SCons.Scanner.Scanner(
+        function=new_scanner,
+        path_function=SCons.Script.FindPathDirs('CPPPATH'),
+        argument=builder.source_scanner,
+    )
+
+def generate(env, **kwargs):
+    if not 'FORCEINCLUDEPREFIX' in env:
+        if 'msvc' in env.get('TOOLS', []):
+            env['FORCEINCLUDEPREFIX'] = '/FI'
+        else:
+            env['FORCEINCLUDEPREFIX'] = '-include '
+
+    if not 'FORCEINCLUDESUFFIX' in env:
+        env['FORCEINCLUDESUFFIX'] = ''
+
+    # Expand FORCEINCLUDES with the indicated prefixes and suffixes.
+    env['_FORCEINCLUDES'] = '${_concat(FORCEINCLUDEPREFIX, FORCEINCLUDES, FORCEINCLUDESUFFIX, __env__, lambda x: x, TARGET, SOURCE)}'
+
+    env.Append(
+        # It might be better if this went in _CPPINCFLAGS, but it
+        # breaks the MSVC RC builder because the `rc` tool doesn't
+        # honor /FI.  It should be OK to put it in CCFLAGS, unless
+        # there is a compiler that requires that an forced include
+        # only come after the include file search path arguments that
+        # would enable discovery.
+        CCFLAGS=[
+            '$_FORCEINCLUDES',
+        ]
+    )
+
+    for object_builder in SCons.Tool.createObjBuilders(env):
+        _add_scanner(object_builder)
+
+def exists(env):
+    return True