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Support block labels shadowing type identifiers 

SystemVerilog allows a named block label in an inner scope to use the same
name as a visible type identifier from an outer scope. The lexer reports such
names as `TYPE_IDENTIFIER` before the label has been installed, which made
constructs such as:

    typedef int T;
    module test;
      initial begin
        begin : T
        end : T
      end
    endmodule

fail in the block label grammar.

The affected grammar positions are label names, not declarations with an
adjacent type/name ambiguity. Use `identifier_name` for `label_opt` and for the
anachronistic named generate begin form so a token returned as `TYPE_IDENTIFIER`
can still be accepted as the label name. With `label_opt` able to handle
`TYPE_IDENTIFIER`, the separate class end-label rule is no longer needed.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
This commit is contained in:
Lars-Peter Clausen 2026-07-04 12:22:18 -07:00
parent 15277c9fa4
commit 06740d0dda
1 changed files with 4 additions and 12 deletions
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parse.y
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@ -879,7 +879,7 @@ Module::port_t *module_declare_interface_port(const YYLTYPE&loc, char *type,
%type <wires> udp_port_decl udp_port_decls
%type <statement> udp_initial udp_init_opt
%type <text> event_variable label_opt class_declaration_endlabel_opt
%type <text> event_variable label_opt
%type <text> block_identifier_opt
%type <text> identifier_name
%type <identifiers> event_variable_list
@ -1126,7 +1126,7 @@ class_declaration /* IEEE1800-2005: A.1.2 */
{ // Process a class.
pform_end_class_declaration(@9);
}
class_declaration_endlabel_opt
label_opt
{ // Wrap up the class.
check_end_label(@11, "class", $4, $11);
delete[] $4;
@ -1145,14 +1145,6 @@ identifier_name
| TYPE_IDENTIFIER { $$ = $1.text; }
;
/* The endlabel after a class declaration is a little tricky because
the class name is detected by the lexor as a TYPE_IDENTIFIER if it
does indeed match a name. */
class_declaration_endlabel_opt
: ':' identifier_name { $$ = $2; }
| { $$ = 0; }
;
/* This rule implements [ extends class_type ] in the
class_declaration. It is not a rule of its own in the LRM.
@ -5217,7 +5209,7 @@ module_end
;
label_opt
: ':' IDENTIFIER { $$ = $2; }
: ':' identifier_name { $$ = $2; }
| { $$ = 0; }
;
@ -5787,7 +5779,7 @@ generate_item
cerr << @1 << ": warning: Anachronistic use of begin/end to surround generate schemes." << endl;
}
}
| K_begin ':' IDENTIFIER
| K_begin ':' identifier_name
{ pform_start_generate_nblock(@1, $3); }
generate_item_list_opt K_end
{ /* Detect and warn about anachronistic named begin/end use */