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Fix a longstanding bug uncovered by bro-0.9a9/src/parse.y, which I

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got from <http://bro-ids.org/download.html>.  The bug is that
when two actions appeared in succession, the second one was
scanned before the first one was added to the grammar rule
as a midrule action.  Bison then output the incorrect warning
"parse.y:905.17-906.36: warning: unused value: $3".
* src/parse-gram.y (BRACED_CODE, action): These are no longer
associated with a value.
(rhs): Don't invoke grammar_current_rule_action_append.
(action): Invoke it here instead.
* src/reader.c (grammar_midrule_action): Now extern.
(grammar_current_rule_action_append): Don't invoke
grammar_midrule_action; that is now the scanner's job.
* src/reader.h (last_string, last_braced_code_loc):
(grammar_midrule_action): New decls.
* src/scan-gram.l (last_string): Now extern, sigh.
(last_braced_code_loc): New extern variable.
(<INITIAL>"{"): Invoke grammar_midrule_action if the current
rule already has an action.
(<SC_BRACED_CODE>"}"): Set last_braced_code_loc before returning.
* tests/input.at (AT_CHECK_UNUSED_VALUES):
Add some tests to check that the above changes fixed the bug.
This commit is contained in:
Paul Eggert
2006-01-30 07:26:00 +00:00
parent d40ba6c272
commit 6b7022680e
6 changed files with 68 additions and 19 deletions
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17
src/parse-gram.y
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@@ -176,7 +176,6 @@ static int current_prec = 0;
"%parse-param {...}"
"%printer {...}"
"%union {...}"
BRACED_CODE action
PROLOGUE EPILOGUE
%printer { fprintf (stderr, "\"%s\"", $$); }
STRING string_content
@@ -187,7 +186,6 @@ static int current_prec = 0;
"%parse-param {...}"
"%printer {...}"
"%union {...}"
BRACED_CODE action
PROLOGUE EPILOGUE
%type <uniqstr> TYPE
%printer { fprintf (stderr, "<%s>", $$); } TYPE
@@ -430,7 +428,6 @@ rhs:
| rhs symbol
{ grammar_current_rule_symbol_append ($2, @2); }
| rhs action
{ grammar_current_rule_action_append ($2, @2); }
| rhs "%prec" symbol
{ grammar_current_rule_prec_set ($3, @3); }
| rhs "%dprec" INT
@@ -444,9 +441,21 @@ symbol:
| string_as_id { $$ = $1; }
;
/* Handle the semantics of an action specially, with a mid-rule
action, so that grammar_current_rule_action_append is invoked
immediately after the braced code is read by the scanner.
This implementation relies on the LALR(1) parsing algorithm.
If grammar_current_rule_action_append were executed in a normal
action for this rule, then when the input grammar contains two
successive actions, the scanner would have to read both actions
before reducing this rule. That wouldn't work, since the scanner
relies on all preceding input actions being processed by
grammar_current_rule_action_append before it scans the next
action. */
action:
{ grammar_current_rule_action_append (last_string, last_braced_code_loc); }
BRACED_CODE
{ $$ = $1; }
;
/* A string used as an ID: quote it. */