From 0471e2780fe528dae8b67ea3448e8ab641e8510e Mon Sep 17 00:00:00 2001 From: Yiming Lei Date: Tue, 9 Aug 2022 11:27:04 -0700 Subject: when there are 3 or more return statements in the loop emit the first 3 errors and duplicated diagnostic information using take of iterator for the first third return modified: compiler/rustc_typeck/src/check/coercion.rs new file: src/test/ui/typeck/issue-100285.rs new file: src/test/ui/typeck/issue-100285.stderr --- compiler/rustc_typeck/src/check/coercion.rs | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'compiler') diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs index 540a8c3a83d..cc400e1ed75 100644 --- a/compiler/rustc_typeck/src/check/coercion.rs +++ b/compiler/rustc_typeck/src/check/coercion.rs @@ -1590,7 +1590,9 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { let hir::ExprKind::Loop(_, _, _, loop_span) = expr.kind else { return;}; let mut span: MultiSpan = vec![loop_span].into(); span.push_span_label(loop_span, "this might have zero elements to iterate on"); - for ret_expr in ret_exprs { + const MAXITER: usize = 3; + let iter = ret_exprs.iter().take(MAXITER); + for ret_expr in iter { span.push_span_label( ret_expr.span, "if the loop doesn't execute, this value would never get returned", @@ -1600,6 +1602,12 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { span, "the function expects a value to always be returned, but loops might run zero times", ); + if MAXITER < ret_exprs.len() { + err.note(&format!( + "if the loop doesn't execute, {} other values would never get returned", + ret_exprs.len() - MAXITER + )); + } err.help( "return a value for the case when the loop has zero elements to iterate on, or \ consider changing the return type to account for that possibility", -- cgit 1.4.1-3-g733a5