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lalr1.cc: don't discard non-existent lookahead on syntax error.

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* data/lalr1.cc (parser::parse): Check yyempty first.
* tests/c++.at (Syntax error discarding no lookahead): New test
group.
This commit is contained in:
Joel E. Denny
2009-12-18 23:57:18 -05:00
parent 387b4d5047
commit d59beda068
3 changed files with 85 additions and 3 deletions
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79
tests/c++.at
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@@ -286,8 +286,6 @@ AT_CHECK_DOXYGEN([Public])
AT_CHECK_DOXYGEN([Private])
## ------------ ##
## Namespaces. ##
## ------------ ##
@@ -369,3 +367,80 @@ AT_CHECK_NAMESPACE([[foo[3]::bar::baz]], [[-]])
AT_CHECK_NAMESPACE([[foo::bar,baz]], [[-]])
AT_CHECK_NAMESPACE([[foo::bar::(baz /* Pacify Emacs ) */]], [[-]])
AT_CLEANUP
## -------------------------------------- ##
## Syntax error discarding no lookahead. ##
## -------------------------------------- ##
# After a syntax error, lalr1.cc used to not check whether there
# actually is a lookahead before discarding the lookahead. As a result,
# it mistakenly invoked the destructor for the previous lookahead.
AT_SETUP([[Syntax error discarding no lookahead]])
AT_DATA_GRAMMAR([[input.yy]],
[[%skeleton "lalr1.cc"
%code {
#include <string>
int yylex (yy::parser::semantic_type *, yy::location *);
#define USE(Args)
}
%defines
%locations
%define parse.error verbose
%nonassoc 'a' ;
%destructor {
std::cerr << "Discarding 'a'." << std::endl;
} 'a'
%%
start: error-reduce consistent-error 'a' { USE ($3); };
error-reduce:
'a' 'a' consistent-error 'a' { USE (($1, $2, $4)); }
| 'a' error { std::cerr << "Reducing 'a'." << std::endl; USE ($1); }
;
consistent-error:
'a'
| /*empty*/ %prec 'a'
;
%%
int
yylex (yy::parser::semantic_type *, yy::location *)
{
static char const *input = "aa";
return *input++;
}
void
yy::parser::error (const location_type &, const std::string &m)
{
std::cerr << m << std::endl;
}
int
main (void)
{
yy::parser parser;
return parser.parse ();
}
]])
AT_BISON_CHECK([[-o input.cc input.yy]], [[0]], [[]], [[ignore-nolog]])
AT_COMPILE_CXX([[input]])
# This used to print "Discarding 'a'." again at the end.
AT_PARSER_CHECK([[./input]], [[1]], [[]],
[[syntax error
Discarding 'a'.
Reducing 'a'.
]])
AT_CLEANUP