diff options
| -rw-r--r-- | compiler/rustc_typeck/src/check/coercion.rs | 10 | ||||
| -rw-r--r-- | src/test/ui/typeck/issue-100285.rs | 22 | ||||
| -rw-r--r-- | src/test/ui/typeck/issue-100285.stderr | 34 |
3 files changed, 65 insertions, 1 deletions
diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs index 6c6bbfa22e3..da575cb1367 100644 --- a/compiler/rustc_typeck/src/check/coercion.rs +++ b/compiler/rustc_typeck/src/check/coercion.rs @@ -1594,7 +1594,9 @@ 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", @@ -1604,6 +1606,12 @@ 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", diff --git a/src/test/ui/typeck/issue-100285.rs b/src/test/ui/typeck/issue-100285.rs new file mode 100644 index 00000000000..e206469b85f --- /dev/null +++ b/src/test/ui/typeck/issue-100285.rs @@ -0,0 +1,22 @@ +fn foo(n: i32) -> i32 { + for i in 0..0 { + //~^ ERROR: mismatched types [E0308] + if n < 0 { + return i; + } else if n < 10 { + return 1; + } else if n < 20 { + return 2; + } else if n < 30 { + return 3; + } else if n < 40 { + return 4; + } else { + return 5; + } + + } + //~| 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 +} + +fn main() {} diff --git a/src/test/ui/typeck/issue-100285.stderr b/src/test/ui/typeck/issue-100285.stderr new file mode 100644 index 00000000000..42c64b03918 --- /dev/null +++ b/src/test/ui/typeck/issue-100285.stderr @@ -0,0 +1,34 @@ +error[E0308]: mismatched types + --> $DIR/issue-100285.rs:2:5 + | +LL | fn foo(n: i32) -> i32 { + | --- expected `i32` because of return type +LL | / for i in 0..0 { +LL | | +LL | | if n < 0 { +LL | | return i; +... | +LL | | +LL | | } + | |_____^ expected `i32`, found `()` + | +note: the function expects a value to always be returned, but loops might run zero times + --> $DIR/issue-100285.rs:2:5 + | +LL | for i in 0..0 { + | ^^^^^^^^^^^^^ this might have zero elements to iterate on +... +LL | return i; + | -------- if the loop doesn't execute, this value would never get returned +LL | } else if n < 10 { +LL | return 1; + | -------- if the loop doesn't execute, this value would never get returned +LL | } else if n < 20 { +LL | return 2; + | -------- if the loop doesn't execute, this value would never get returned + = note: if the loop doesn't execute, 3 other values would never get returned + = 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 + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0308`. |