Hi, I've been spending a bit of time with the distcc include_server trying to
get a handle on issue #16. I'm making progress but not quite got a fix just
yet. Here's what I've got so far.
Firstly I think the ## substitution in macro_eval.py is not quite right because
it doesn't support whitespace around the ## operator. This is used in boost and
is at least part of the problem with issue #16. Fortunately it's an easy fix:
=== modified file 'include_server/macro_eval.py'
--- include_server/macro_eval.py 2009-01-30 17:27:30 +0000
+++ include_server/macro_eval.py 2011-02-13 10:23:12 +0000
@@ -142,7 +142,7 @@
# REGULAR EXPRESSIONS
SINGLE_POUND_RE = re.compile(r"\B#\s*(\S*)") # \B = here: not at end of word
-DOUBLE_POUND_RE = re.compile(r"##")
+DOUBLE_POUND_RE = re.compile(r"\s*##\s*")
SYMBOL_RE = re.compile(r"\b\w+\b") # \b = word boundary \w = word constituent
Secondly I want to question the decision to include the unsubstituted macro
call in the set of possible values for expansion. I understand the
justification for this for non-function-like macros, and for the preprocessor
in general, but for the limited cases of macro expansion that the
include_server needs (ie pretty much just calculated includes), it doesn't seem
to add a lot of value.
I guess in theory there could be include files which look like macro
invocations to the parser but are in fact real files. I'm not sure if there are
any real examples of this happening, but it seems to me the cost of handling
these things could be quite high. At least, the proliferation of unexpanded
macros into the value_set contributes to a combinatorial explosion which I
believe is at the heart of issue #16.
In the interest of clarity, the following test case diff should explain what I
think is correct behaviour from macro_eval.py:
=== modified file 'include_server/macro_eval_test.py'
--- include_server/macro_eval_test.py 2008-07-29 21:19:10 +0000
+++ include_server/macro_eval_test.py 2011-02-13 10:53:30 +0000
@@ -102,26 +102,33 @@
self.assertEqual(
macro_eval.EvalExpression("max(2, 4)",
{ 'max': [ ( ['x', 'y'], "x < y? y: x") ] }),
- set(['max(2, 4)', '2 < 4? 4: 2']))
+ set(['2 < 4? 4: 2']))
self.assertEqual(
macro_eval.EvalExpression("F(2, 4)",
{ 'F': ['max'],
'max': [ ( ['x', 'y'], "x < y? y: x") ] }),
- set(['max(2, 4)', 'F(2, 4)', '2 < 4? 4: 2']))
+ set(['2 < 4? 4: 2']))
self.assertEqual(
macro_eval.EvalExpression("max(max(1,2), 3)",
{ 'max': [ ( ['x', 'y'], "(x < y? y: x)") ] }),
- set(['((1 < 2? 2: 1) < 3? 3: (1 < 2? 2: 1))',
- 'max(max(1,2), 3)',
- '(max(1,2) < 3? 3: max(1,2))',
- 'max((1 < 2? 2: 1), 3)']))
+ set(['((1 < 2? 2: 1) < 3? 3: (1 < 2? 2: 1))']))
self.assertEqual(
Hoping that there are still people interested in working on distcc, it seems to
have gone a bit quiet of late!
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