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bison -v sql_yacc.yy reports some conflicts caused by the fact that SOUNDS_SYM, ESCAPE_SYM, USER_SYM are not given any precedence.
Summary:
- SOUNDS_SYM should have the same precedence with LIKE and REGEXP (i.e. should be in the same %left directive with LIKE). It seems it was just forgotten.
- ESCAPE_SYM should have its own %left directive with a very low precedence, and the empty branch in the opt_escape rule should have even lower precedence than ESCAPE_SYM. The current parser default behavior is to hungry scan all possible expressions between LIKE and the optional ESCAPE clause. Adding precedence as described for empty and non-empty ESCAPE clauses will preserve this behavior and remove conflicts.
- The "| USER_SYM" line in keyword_sp_var_and_label should have its %prec directive, to treat "USER" as a identifier only if it's not followed by a TEXT_STRING. Similar conflicts were earlier addressed for TRANSACTION_SYM, TIMESTAMP, PERIOD_SYM, SYSTEM (they can also be identifiers, or can have a special meaning).
The relevant bison -v output pieces:
State 1019
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...
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1482 | bit_expr . SOUNDS_SYM LIKE bit_expr
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...
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SOUNDS_SYM shift, and go to state 1548
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SOUNDS_SYM [reduce using rule 1487 (predicate)]
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State 1963
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1612 function_call_keyword: USER_SYM . '(' ')'
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2366 kill_expr: USER_SYM . user
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2952 keyword_sp_var_and_label: USER_SYM .
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USER_SYM shift, and go to state 557
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SOUNDS_SYM [reduce using rule 2952 (keyword_sp_var_and_label)]
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State 2183
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1483 predicate: bit_expr LIKE mysql_concatenation_expr . opt_escape
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1591 mysql_concatenation_expr: mysql_concatenation_expr . MYSQL_CONCAT_SYM simple_expr
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MYSQL_CONCAT_SYM shift, and go to state 1560
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ESCAPE_SYM shift, and go to state 2827
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MYSQL_CONCAT_SYM [reduce using rule 1923 (opt_escape)]
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ESCAPE_SYM [reduce using rule 1923 (opt_escape)]
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$default reduce using rule 1923 (opt_escape)
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opt_escape go to state 2828
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State 2834
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1484 predicate: bit_expr not LIKE mysql_concatenation_expr . opt_escape
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1591 mysql_concatenation_expr: mysql_concatenation_expr . MYSQL_CONCAT_SYM simple_expr
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MYSQL_CONCAT_SYM shift, and go to state 1560
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ESCAPE_SYM shift, and go to state 2827
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MYSQL_CONCAT_SYM [reduce using rule 1923 (opt_escape)]
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ESCAPE_SYM [reduce using rule 1923 (opt_escape)]
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$default reduce using rule 1923 (opt_escape)
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opt_escape go to state 3407
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