Issue 3554: Avoid empty grammar rules using @$ for getting a source location

Several rules use @$ for getting the source position from an empty
rule, but Bison does not even provide a source position for empty
rules.

This patch fixes most cases by letting different non-empty rules
assign the respective source positions.  The case of #{ #} cannot be
fixed in that manner since there is not a single token providing a
source position in the whole production.  Fixing this particular case
would require a different technique.

diff --git a/lily/parser.yy b/lily/parser.yy
index 11d8d17125991e7a2eb3510ec3592b49f2335cc3..dd0f09fb93cca4c0fb085d1ffac748f1d0228103 100644 (file)
--- a/lily/parser.yy
+++ b/lily/parser.yy
@@ -523,6 +523,10 @@ scm_function_call:
 embedded_lilypond:
        /* empty */
        {
+               // FIXME: @$ does not contain a useful source location
+               // for empty rules, and the only token in the whole
+               // production, EMBEDDED_LILY, is synthetic and also
+               // contains no source location.
                $$ = MAKE_SYNTAX ("void-music", @$);
        }
        | identifier_init
@@ -622,6 +626,7 @@ context_def_spec_block:
        CONTEXT '{' context_def_spec_body '}'
                {
                $$ = $3;
+               unsmob_context_def ($$)->origin ()->set_spot (@$);
        }
        ;
 
@@ -659,11 +664,9 @@ context_mod_embedded:
 context_def_spec_body:
        /**/ {
                $$ = Context_def::make_scm ();
-               unsmob_context_def ($$)->origin ()->set_spot (@$);
        }
        | CONTEXT_DEF_IDENTIFIER {
                $$ = $1;
-               unsmob_context_def ($$)->origin ()->set_spot (@$);
        }
        | context_def_spec_body context_mod {
                if (!SCM_UNBNDP ($2))
@@ -690,6 +693,7 @@ context_def_spec_body:
 book_block:
        BOOK '{' book_body '}'  {
                $$ = $3;
+               unsmob_book ($$)->origin ()->set_spot (@$);
                pop_paper (parser);
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-book"), SCM_BOOL_F);
        }
@@ -702,7 +706,6 @@ book_body:
        {
                Book *book = new Book;
                init_papers (parser);
-               book->origin ()->set_spot (@$);
                book->paper_ = dynamic_cast<Output_def*> (unsmob_output_def (parser->lexer_->lookup_identifier ("$defaultpaper"))->clone ());
                book->paper_->unprotect ();
                push_paper (parser, book->paper_);
@@ -711,7 +714,6 @@ book_body:
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-book"), $$);
        }
        | BOOK_IDENTIFIER {
-               unsmob_book ($1)->origin ()->set_spot (@$);
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-book"), $1);
        }
        | book_body paper_block {
@@ -771,6 +773,7 @@ book_body:
 bookpart_block:
        BOOKPART '{' bookpart_body '}' {
                $$ = $3;
+               unsmob_book ($$)->origin ()->set_spot (@$);
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-bookpart"), SCM_BOOL_F);
        }
        ;
@@ -778,12 +781,10 @@ bookpart_block:
 bookpart_body:
        {
                Book *book = new Book;
-               book->origin ()->set_spot (@$);
                 $$ = book->unprotect ();
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-bookpart"), $$);
        }
        | BOOK_IDENTIFIER {
-               unsmob_book ($1)->origin ()->set_spot (@$);
                parser->lexer_->set_identifier (ly_symbol2scm ("$current-bookpart"), $1);
        }
        | bookpart_body paper_block {
@@ -955,6 +956,7 @@ music_or_context_def:
        } '{' context_def_spec_body '}'
        {
                $$ = $4;
+               unsmob_context_def ($$)->origin ()->set_spot (@$);
        }
        ;