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master: improve accuracy of locations in error messages about nontermina
From: |
Akim Demaille |
Subject: |
master: improve accuracy of locations in error messages about nonterminals |
Date: |
Wed, 14 Jan 2015 17:06:08 +0100 |
commit 875ef1b90c4cbdc637b6944d4d6eb5b2b7bb7eef
Author: Akim Demaille <address@hidden>
Date: Wed Jan 14 13:41:32 2015 +0100
symbol: use the first occurrence as an LHS as defining location
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.
diff --git a/NEWS b/NEWS
index e64c6e8..bba0f5f 100644
--- a/NEWS
+++ b/NEWS
@@ -33,13 +33,14 @@ GNU Bison NEWS
^^^^^^^^^^^
Now, rules whose left-hand side symbol is useless are no longer reported
- as useless.
+ as useless. The locations of the errors have also been adjusted to point
+ to the first use of the nonterminal as a left-hand side of a rule:
warning: 1 nonterminal useless in grammar [-Wother]
warning: 4 rules useless in grammar [-Wother]
- 2.14-16: warning: nonterminal useless in grammar: exp [-Wother]
- input: '0' | exp
- ^^^
+ 3.1-3: warning: nonterminal useless in grammar: exp [-Wother]
+ exp: exp '+' exp | exp '-' exp | '(' exp ')'
+ ^^^
2.14-16: warning: rule useless in grammar [-Wother]
input: '0' | exp
^^^
diff --git a/src/parse-gram.c b/src/parse-gram.c
index 825e2b0..43eeaeb 100644
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 3.0.2.13-975bb-dirty. */
+/* A Bison parser, made by GNU Bison 3.0.2.29-9a91e. */
/* Bison implementation for Yacc-like parsers in C
@@ -44,7 +44,7 @@
#define YYBISON 1
/* Bison version. */
-#define YYBISON_VERSION "3.0.2.13-975bb-dirty"
+#define YYBISON_VERSION "3.0.2.29-9a91e"
/* Skeleton name. */
#define YYSKELETON_NAME "yacc.c"
@@ -3118,6 +3118,8 @@ current_lhs (symbol *sym, location loc, named_ref *ref)
{
current_lhs_symbol = sym;
current_lhs_location = loc;
+ if (sym)
+ symbol_location_as_lhs_set (sym, loc);
/* In order to simplify memory management, named references for lhs
are always assigned by deep copy into the current symbol_list
node. This is because a single named-ref in the grammar may
diff --git a/src/parse-gram.h b/src/parse-gram.h
index c40151d..26bb3c5 100644
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -1,4 +1,4 @@
-/* A Bison parser, made by GNU Bison 3.0.2.13-975bb-dirty. */
+/* A Bison parser, made by GNU Bison 3.0.2.29-9a91e. */
/* Bison interface for Yacc-like parsers in C
diff --git a/src/parse-gram.y b/src/parse-gram.y
index 9184d5f..5a0b200 100644
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -865,6 +865,8 @@ current_lhs (symbol *sym, location loc, named_ref *ref)
{
current_lhs_symbol = sym;
current_lhs_location = loc;
+ if (sym)
+ symbol_location_as_lhs_set (sym, loc);
/* In order to simplify memory management, named references for lhs
are always assigned by deep copy into the current symbol_list
node. This is because a single named-ref in the grammar may
diff --git a/src/symtab.c b/src/symtab.c
index 02b3eae..9524773 100644
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -105,6 +105,7 @@ symbol_new (uniqstr tag, location loc)
res->tag = tag;
res->location = loc;
+ res->location_of_lhs = false;
res->alias = NULL;
res->content = sym_content_new (res);
res->is_alias = false;
@@ -189,6 +190,7 @@ code_props_type_string (code_props_type kind)
assert (0);
}
+
/*----------------------------------------.
| Create a new semantic type, named TAG. |
`----------------------------------------*/
@@ -307,6 +309,13 @@ semantic_type_redeclaration (semantic_type *s, const char
*what, location first,
}
+void
+symbol_location_as_lhs_set (symbol *sym, location loc)
+{
+ if (!sym->location_of_lhs)
+ sym->location = loc;
+}
+
/*-----------------------------------------------------------------.
| Set the TYPE_NAME associated with SYM. Does nothing if passed 0 |
diff --git a/src/symtab.h b/src/symtab.h
index 9719cd3..42d479c 100644
--- a/src/symtab.h
+++ b/src/symtab.h
@@ -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. */
diff --git a/tests/reduce.at b/tests/reduce.at
index c7edb10..d197dc6 100644
--- a/tests/reduce.at
+++ b/tests/reduce.at
@@ -254,9 +254,9 @@ not-reduced.y: warning: 3 rules useless in grammar [-Wother]
not-reduced.y:14.1-13: warning: nonterminal useless in grammar: not_reachable
[-Wother]
not_reachable: useful { /* A not reachable action. */ }
^^^^^^^^^^^^^
-not-reduced.y:11.6-19: warning: nonterminal useless in grammar: non_productive
[-Wother]
- | non_productive { /* A non productive action. */ }
- ^^^^^^^^^^^^^^
+not-reduced.y:17.1-14: warning: nonterminal useless in grammar: non_productive
[-Wother]
+ non_productive: non_productive useless_token
+ ^^^^^^^^^^^^^^
not-reduced.y:11.6-57: warning: rule useless in grammar [-Wother]
| non_productive { /* A non productive action. */ }
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -330,12 +330,12 @@ indirection: underivable;
AT_BISON_CHECK([[-fcaret input.y]], 0, [],
[[input.y: warning: 2 nonterminals useless in grammar [-Wother]
input.y: warning: 3 rules useless in grammar [-Wother]
-input.y:5.15-25: warning: nonterminal useless in grammar: underivable [-Wother]
- exp: useful | underivable;
- ^^^^^^^^^^^
-input.y:6.14-24: warning: nonterminal useless in grammar: indirection [-Wother]
+input.y:6.1-11: warning: nonterminal useless in grammar: underivable [-Wother]
underivable: indirection;
- ^^^^^^^^^^^
+ ^^^^^^^^^^^
+input.y:7.1-11: warning: nonterminal useless in grammar: indirection [-Wother]
+ indirection: underivable;
+ ^^^^^^^^^^^
input.y:5.15-25: warning: rule useless in grammar [-Wother]
exp: useful | underivable;
^^^^^^^^^^^
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