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Fix #1112: Report error for invalid $bits argument 

When $bits() is called with an undefined identifier, the compiler now
properly reports an error instead of silently returning 0.

The fix checks if the argument expression has type IVL_VT_NO_TYPE after
test_width() processing (indicating the identifier couldn't be resolved),
and triggers elaboration to produce a proper error message.

Includes regression test: br_gh1112

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Andrew Pullin 2026-01-23 10:56:13 -08:00
parent f040d513a5
commit 5b8fac5441
4 changed files with 18 additions and 0 deletions
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9
elab_expr.cc
View File

@ -1983,6 +1983,15 @@ NetExpr* PECallFunction::elaborate_sfunc_(Design*des, NetScope*scope,
}
} else {
// Check if the expression could be resolved. If test_width
// failed to find the identifier, expr_type will be NO_TYPE.
if (expr->expr_type() == IVL_VT_NO_TYPE) {
// Try to elaborate the expression to get a proper error
// message about the undefined identifier.
NetExpr *tmp = expr->elaborate_expr(des, scope, (unsigned)1, flags);
if (tmp) delete tmp;
return 0;
}
use_width = expr->expr_width();
if (debug_elaborate) {
cerr << get_fileline() << ": PECallFunction::elaborate_sfunc_: "

2
ivtest/gold/br_gh1112.gold Normal file
View File

@ -0,0 +1,2 @@
./ivltests/br_gh1112.v:4: error: Unable to bind parameter `value' in `top'
1 error(s) during elaboration.

6
ivtest/ivltests/br_gh1112.v Normal file
View File

@ -0,0 +1,6 @@
// Test for GitHub issue #1112
// $bits() with non-existent identifier should produce an error
module top;
localparam width = $bits(value); // 'value' doesn't exist - should error
initial $display(width);
endmodule

1
ivtest/regress-sv.list
View File

@ -989,3 +989,4 @@ partsel_real_idx CE,-g2012 ivltests gold=partsel_real_idx.gold
ipsdownsel_real_idx CE,-g2012 ivltests gold=ipsdownsel_real_idx.gold
ipsupsel_real_idx CE,-g2012 ivltests gold=ipsupsel_real_idx.gold
real_edges CE,-g2012 ivltests gold=real_edges.gold
br_gh1112 CE,-g2009 ivltests gold=br_gh1112.gold