diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs index 71521abb538..84532e718e5 100644 --- a/src/comp/middle/ty.rs +++ b/src/comp/middle/ty.rs @@ -2004,8 +2004,11 @@ mod unify { (ures_err(terr_mode_mismatch(expected_input.mode, actual_input.mode))); } else { expected_input.mode }; + // The variance changes (flips basically) when descending + // into arguments of function types let result = unify_step( - cx, expected_input.ty, actual_input.ty, variance); + cx, expected_input.ty, actual_input.ty, + variance_transform(variance, contravariant)); alt result { ures_ok(rty) { result_ins += [{mode: result_mode, ty: rty}]; } _ { ret fn_common_res_err(result); } diff --git a/src/test/compile-fail/block-coerce-no-2.rs b/src/test/compile-fail/block-coerce-no-2.rs new file mode 100644 index 00000000000..926e39529ea --- /dev/null +++ b/src/test/compile-fail/block-coerce-no-2.rs @@ -0,0 +1,14 @@ +// error-pattern: mismatched types + +// Make sure that fn-to-block coercion isn't incorrectly lifted over +// other tycons. + +fn main() { + fn f(f: fn(fn(fn()))) { + } + + fn g(f: fn(block())) { + } + + f(g); +}