Improve error messages for `$' or `@' followed by `.' or `-'.

Previously, for this special case of an invalid reference, the
usual "symbol not found in production:" was printed.  However,
because the symbol name was parsed as the empty string, that
message was followed immediately by a newline instead of a symbol
name.  In reality, this is a syntax error, so the reference is
invalid regardless of the symbols actually appearing in the
production.  Discussed at
<http://lists.gnu.org/archive/html/bison-patches/2011-01/msg00012.html>.
* src/scan-code.l (parse_ref): Report the above case as a syntax
error.  Other than that, continue to handle this case like any
other invalid reference that Bison manages to parse because
"possibly meant" messages can still be helpful to the user.
* tests/named-refs.at ($ or @ followed by . or -): New test group.
(cherry picked from commit 5c9efc755e61e47011a71b022ad232e28af67bd0)

diff --git a/ChangeLog b/ChangeLog
index 26610a7c054d9ebc8ba7cfe06c84b90cf1549fdc..1ff0f09dce5fc44061447d1702a747f98e157340 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2011-01-09  Joel E. Denny  <joeldenny@joeldenny.org>
+
+       Improve error messages for `$' or `@' followed by `.' or `-'.
+       Previously, for this special case of an invalid reference, the
+       usual "symbol not found in production:" was printed.  However,
+       because the symbol name was parsed as the empty string, that
+       message was followed immediately by a newline instead of a symbol
+       name.  In reality, this is a syntax error, so the reference is
+       invalid regardless of the symbols actually appearing in the
+       production.  Discussed at
+       <http://lists.gnu.org/archive/html/bison-patches/2011-01/msg00012.html>.
+       * src/scan-code.l (parse_ref): Report the above case as a syntax
+       error.  Other than that, continue to handle this case like any
+       other invalid reference that Bison manages to parse because
+       "possibly meant" messages can still be helpful to the user.
+       * tests/named-refs.at ($ or @ followed by . or -): New test group.
+
 2011-01-08  Joel E. Denny  <joeldenny@joeldenny.org>
 
        doc: don't use @acronym.

diff --git a/src/scan-code.l b/src/scan-code.l
index e3e6b6536e93417ce043d1a36537ed06070e57c4..0158e7c02dbac2a48c79f32ec8497b2687dd66f1 100644 (file)
--- a/src/scan-code.l
+++ b/src/scan-code.l
@@ -620,7 +620,17 @@ parse_ref (char *cp, symbol_list *rule, int rule_length,
         complain_at_indent (text_loc, &indent, _("invalid reference: %s"),
                             quote (text));
         indent += SUB_INDENT;
-        if (midrule_rhs_index)
+        if (len == 0)
+          {
+            location sym_loc = text_loc;
+            sym_loc.start.column += 1;
+            sym_loc.end = sym_loc.start;
+            const char *format =
+              _("syntax error after `%c', expecting integer, letter,"
+                " `_', `[', or `$'");
+            complain_at_indent (sym_loc, &indent, format, dollar_or_at);
+          }
+        else if (midrule_rhs_index)
           {
             const char *format =
               _("symbol not found in production before $%d: %.*s");

diff --git a/tests/named-refs.at b/tests/named-refs.at
index 25af97de3fae417598eeeb6b33a327556a085834..f818e0944be2d5462470ec92f811c58d021c8092 100644 (file)
--- a/tests/named-refs.at
+++ b/tests/named-refs.at
@@ -561,3 +561,32 @@ test.y:57.8-17: invalid reference: `$<aa>[sym]'
 test.y:54.1-57.21:  symbol not found in production: sym
 ]])
 AT_CLEANUP
+
+#######################################################################
+
+AT_SETUP([[$ or @ followed by . or -]])
+AT_DATA([[test.y]],
+[[
+%%
+start:
+  .field { $.field; }
+| -field { @-field; }
+| 'a'    { @.field; }
+| 'a'    { $-field; }
+;
+.field: ;
+-field: ;
+]])
+AT_BISON_CHECK([[test.y]], [[1]], [],
+[[test.y:4.12-18: invalid reference: `$.field'
+test.y:4.13:        syntax error after `$', expecting integer, letter, `_', `@<:@', or `$'
+test.y:4.3-8:       possibly meant: $[.field] at $1
+test.y:5.12-18: invalid reference: `@-field'
+test.y:5.13:        syntax error after `@', expecting integer, letter, `_', `@<:@', or `$'
+test.y:5.3-8:       possibly meant: @[-field] at $1
+test.y:6.12-18: invalid reference: `@.field'
+test.y:6.13:        syntax error after `@', expecting integer, letter, `_', `@<:@', or `$'
+test.y:7.12-18: invalid reference: `$-field'
+test.y:7.13:        syntax error after `$', expecting integer, letter, `_', `@<:@', or `$'
+]])
+AT_CLEANUP