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symbol: use the first occurrence as an LHS as defining location

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Currently on the following grammar:

    %type <foo> foo
    %%
    start: foo | bar | "baz"
    foo: foo
    bar: bar

bison reports:

    warning: 2 nonterminals useless in grammar [-Wother]
    warning: 4 rules useless in grammar [-Wother]
    1.13-15: warning: nonterminal useless in grammar: foo [-Wother]
     %type <foo> foo
                 ^^^
    3.14-16: warning: nonterminal useless in grammar: bar [-Wother]
     start: foo | bar | "baz"
                  ^^^
    [...]

i.e., the location of the first occurrence of a symbol is taken as its
definition point.  In the case of nonterminals, the first occurrence
as a left-hand side of a rule makes more sense:

    warning: 2 nonterminals useless in grammar [-Wother]
    warning: 4 rules useless in grammar [-Wother]
    4.1-3: warning: nonterminal useless in grammar: foo [-Wother]
     foo: foo
     ^^^
    5.1-3: warning: nonterminal useless in grammar: bar [-Wother]
     bar: bar
     ^^^
    [...]

* src/symtab.h, src/symtab.c (symbol::location_of_lhs): New.
(symbol_location_as_lhs_set): New.
* src/parse-gram.y (current_lhs): Use it.
* tests/reduce.at: Update locations.
This commit is contained in:
Akim Demaille
2015-01-14 13:41:32 +01:00
parent 650af77812
commit 875ef1b90c
7 changed files with 46 additions and 17 deletions
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19
src/symtab.h
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@@ -87,10 +87,19 @@ struct symbol
{
/** The key, name of the symbol. */
uniqstr tag;
/** The location of its first occurrence. */
/** The "defining" location. */
location location;
/* Points to the other in the symbol-string pair for an alias. */
/** Whether \a location is about the first uses as left-hand side
symbol of a rule (true), or simply the first occurrence (e.g.,
in a %type, or as a rhs symbol of a rule). The former type of
location is more natural in error messages. This Boolean helps
moving from location of the first occurrence to first use as
lhs. */
bool location_of_lhs;
/** Points to the other in the symbol-string pair for an alias. */
symbol *alias;
/** Whether this symbol is the alias of another or not. */
@@ -177,6 +186,12 @@ uniqstr symbol_id_get (symbol const *sym);
*/
void symbol_make_alias (symbol *sym, symbol *str, location loc);
/**
* This symbol is used as the lhs of a rule. Record this location
* as definition point, if not already done.
*/
void symbol_location_as_lhs_set (symbol *sym, location loc);
/** Set the \c type_name associated with \c sym.
Do nothing if passed 0 as \c type_name. */