From 702ea7169cc20f3e572576e68339edc0b8fc5939 Mon Sep 17 00:00:00 2001 From: Alex Burka Date: Sun, 21 Aug 2016 22:45:25 +0000 Subject: [PATCH] typeck: use NoExpectation to check return type of diverging fn This fixes #35849, a regression introduced by the typeck refactoring around TyNever/!. --- src/librustc/middle/liveness.rs | 8 +++++++- src/librustc_typeck/check/mod.rs | 8 +++++++- .../compile-fail/diverging-fn-tail-35849.rs | 16 ++++++++++++++++ src/test/run-fail/call-fn-never-arg.rs | 1 + src/test/run-pass/diverging-fn-tail-35849.rs | 18 ++++++++++++++++++ 5 files changed, 49 insertions(+), 2 deletions(-) create mode 100644 src/test/compile-fail/diverging-fn-tail-35849.rs create mode 100644 src/test/run-pass/diverging-fn-tail-35849.rs diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs index 74d29b273ff2b..b83826de26dd6 100644 --- a/src/librustc/middle/liveness.rs +++ b/src/librustc/middle/liveness.rs @@ -1479,7 +1479,13 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { self.ir.tcx.region_maps.call_site_extent(id, body.id), &self.fn_ret(id)); - if self.live_on_entry(entry_ln, self.s.no_ret_var).is_some() { + if fn_ret.is_never() { + // FIXME(durka) this rejects code like `fn foo(x: !) -> ! { x }` + if self.live_on_entry(entry_ln, self.s.clean_exit_var).is_some() { + span_err!(self.ir.tcx.sess, sp, E0270, + "computation may converge in a function marked as diverging"); + } + } else if self.live_on_entry(entry_ln, self.s.no_ret_var).is_some() { let param_env = ParameterEnvironment::for_item(self.ir.tcx, id); let t_ret_subst = fn_ret.subst(self.ir.tcx, ¶m_env.free_substs); let is_nil = self.ir.tcx.infer_ctxt(None, Some(param_env), diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs index 3d51da02b874d..16300d869abf5 100644 --- a/src/librustc_typeck/check/mod.rs +++ b/src/librustc_typeck/check/mod.rs @@ -708,7 +708,13 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>, inherited.tables.borrow_mut().liberated_fn_sigs.insert(fn_id, fn_sig); - fcx.check_block_with_expected(body, ExpectHasType(fcx.ret_ty)); + // FIXME(aburka) do we need this special case? and should it be is_uninhabited? + let expected = if fcx.ret_ty.is_never() { + NoExpectation + } else { + ExpectHasType(fcx.ret_ty) + }; + fcx.check_block_with_expected(body, expected); fcx } diff --git a/src/test/compile-fail/diverging-fn-tail-35849.rs b/src/test/compile-fail/diverging-fn-tail-35849.rs new file mode 100644 index 0000000000000..6dc447b4dc887 --- /dev/null +++ b/src/test/compile-fail/diverging-fn-tail-35849.rs @@ -0,0 +1,16 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +fn _converge() -> ! { //~ ERROR computation may converge + 42 +} + +fn main() { } + diff --git a/src/test/run-fail/call-fn-never-arg.rs b/src/test/run-fail/call-fn-never-arg.rs index 95101e70db951..b1aa76cd9bfe5 100644 --- a/src/test/run-fail/call-fn-never-arg.rs +++ b/src/test/run-fail/call-fn-never-arg.rs @@ -10,6 +10,7 @@ // Test that we can use a ! for an argument of type ! +// ignore-test FIXME(durka) can't be done with the current liveness code // error-pattern:wowzers! #![feature(never_type)] diff --git a/src/test/run-pass/diverging-fn-tail-35849.rs b/src/test/run-pass/diverging-fn-tail-35849.rs new file mode 100644 index 0000000000000..6c05a02e7183c --- /dev/null +++ b/src/test/run-pass/diverging-fn-tail-35849.rs @@ -0,0 +1,18 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +fn assert_sizeof() -> ! { + unsafe { + ::std::mem::transmute::(panic!()) + } +} + +fn main() { } +