debug ice: needless_return suggestion removes code which isnt there inside macro

[matthiaskrgr]

Summary

// run-pass

macro_rules! overly_complicated {
    ($fnname:ident, $arg:ident, $ty:ty, $body:block, $val:expr, $pat:pat, $res:path) =>
    ({
        fn $fnname($arg: $ty) -> Option<$ty> $body
        match $fnname($val) {
          Some($pat) => {
            $res
          }
          _ => { panic!(); }
        }
    })

}

macro_rules! qpath {
    (path, <$type:ty as $trait:path>::$name:ident) => {
        <$type as $trait>::$name
    };

    (ty, <$type:ty as $trait:ty>::$name:ident) => {
        <$type as $trait>::$name
    };
}

pub fn main() {
    let _: qpath!(path, <str as ToOwned>::Owned);
    let _: qpath!(ty, <str as ToOwned>::Owned);

    assert!(overly_complicated!(f, x, Option<usize>, { return Some(x); },
                               Some(8), Some(y), y) == 8)
}

see the first "help" hint:

warning: unneeded `return` statement
  --> /home/matthias/vcs/github/rust_debug_assertions/tests/ui/macros/macro-interpolation.rs:31:56
   |
31 |     assert!(overly_complicated!(f, x, Option<usize>, { return Some(x); },
   |                                                        ^^^^^^^^^^^^^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
   = note: `#[warn(clippy::needless_return)]` on by default
help: remove `return`
   |
6  ~         fn $fnname($arg: $ty) -> Option<$ty> $body
7  |         match $fnname($val) {
 ...
30 |
31 ~     assert!(overly_complicated!(f, x, Option<usize>, { Some(x); },
   |

warning: 1 warning emitted

Version

425726d46b637f94995ca1c95f4f16cdb903d30e

Error output

Backtrace

thread 'rustc' panicked at 'assertion failed: `(left == right)`
left: `Some(SubstitutionPart { span: /home/matthias/vcs/github/rust_debug_assertions/tests/ui/macros/macro-interpolation.rs:6:51: 6:51 (#0), snippet: "" })`,
right: `None`: Span must not be empty and have no suggestion', /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_errors/src/diagnostic.rs:623:9
stack backtrace:
 0:     0x7f4c852c3836 - std::backtrace_rs::backtrace::libunwind::trace::h30fa42aa2db88158
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
 1:     0x7f4c852c3836 - std::backtrace_rs::backtrace::trace_unsynchronized::h2b9cc808f86f85f7
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
 2:     0x7f4c852c3836 - std::sys_common::backtrace::_print_fmt::h268804fe13f30210
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/sys_common/backtrace.rs:65:5
 3:     0x7f4c852c3836 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h692ee2dd29cb6a32
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/sys_common/backtrace.rs:44:22
 4:     0x7f4c85356617 - core::fmt::rt::Argument::fmt::h1dc8855cf0be02de
                             at /home/matthias/vcs/github/rust_debug_assertions/library/core/src/fmt/rt.rs:138:9
 5:     0x7f4c85356617 - core::fmt::write::h35c6f281391d7802
                             at /home/matthias/vcs/github/rust_debug_assertions/library/core/src/fmt/mod.rs:1094:21
 6:     0x7f4c852d2445 - std::io::Write::write_fmt::h5f9eeb8695999550
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/io/mod.rs:1714:15
 7:     0x7f4c852c3635 - std::sys_common::backtrace::_print::h0b343769d5ca97ef
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/sys_common/backtrace.rs:47:5
 8:     0x7f4c852c3635 - std::sys_common::backtrace::print::h1a9dcf70c9d72f51
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/sys_common/backtrace.rs:34:9
 9:     0x7f4c852cce3c - std::panicking::default_hook::{{closure}}::h84517d6843a8b8eb
10:     0x7f4c852ccb0c - std::panicking::default_hook::h9d050be456d2e865
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/panicking.rs:288:9
11:     0x7f4c8712cd7b - <alloc[86fc1011f0da8be9]::boxed::Box<dyn for<'a, 'b> core[1cc32ee8b476061a]::ops::function::Fn<(&'a core[1cc32ee8b476061a]::panic::panic_info::PanicInfo<'b>,), Output = ()> + core[1cc32ee8b476061a]::marker::Sync + core[1cc32ee8b476061a]::marker::Send> as core[1cc32ee8b476061a]::ops::function::Fn<(&core[1cc32ee8b476061a]::panic::panic_info::PanicInfo,)>>::call
                             at /home/matthias/vcs/github/rust_debug_assertions/library/alloc/src/boxed.rs:2021:9
12:     0x7f4c8712cd7b - rustc_driver_impl[f08193399333356b]::install_ice_hook::{closure#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_driver_impl/src/lib.rs:1342:13
13:     0x7f4c852cd625 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h9913b6eac17b3933
                             at /home/matthias/vcs/github/rust_debug_assertions/library/alloc/src/boxed.rs:2021:9
14:     0x7f4c852cd625 - std::panicking::rust_panic_with_hook::hd3dcfd82aa6687cf
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/panicking.rs:709:13
15:     0x7f4c852c41c7 - std::panicking::begin_panic_handler::{{closure}}::h30ada8e3083a8d7e
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/panicking.rs:597:13
16:     0x7f4c852c3a96 - std::sys_common::backtrace::__rust_end_short_backtrace::hc69fe69b4cacc2af
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/sys_common/backtrace.rs:151:18
17:     0x7f4c852cd192 - rust_begin_unwind
                             at /home/matthias/vcs/github/rust_debug_assertions/library/std/src/panicking.rs:593:5
18:     0x7f4c8527a303 - core::panicking::panic_fmt::h2aa9ff874ea77c22
                             at /home/matthias/vcs/github/rust_debug_assertions/library/core/src/panicking.rs:67:14
19:     0x7f4c8527a83b - core::panicking::assert_failed_inner::h4ebd8a79193f4ada
20:     0x563da0f3b9bf - core[1cc32ee8b476061a]::panicking::assert_failed::<core[1cc32ee8b476061a]::option::Option<&rustc_errors[4a72a762f26cae1d]::SubstitutionPart>, core[1cc32ee8b476061a]::option::Option<&rustc_errors[4a72a762f26cae1d]::SubstitutionPart>>
                             at /home/matthias/vcs/github/rust_debug_assertions/library/core/src/panicking.rs:229:5
21:     0x563da11d8576 - <rustc_errors[4a72a762f26cae1d]::diagnostic::Diagnostic>::multipart_suggestion_with_style::<&str>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_errors/src/diagnostic.rs:623:9
22:     0x563da116160b - <rustc_errors[4a72a762f26cae1d]::diagnostic::Diagnostic>::multipart_suggestion_verbose::<&str>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_errors/src/diagnostic.rs:600:9
23:     0x563da116160b - clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_lints/src/returns.rs:326:14
24:     0x563da116160b - clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then::<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_utils/src/diagnostics.rs:149:9
25:     0x563da116160b - <clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0} as core[1cc32ee8b476061a]::ops::function::FnOnce<(&mut rustc_errors[4a72a762f26cae1d]::diagnostic_builder::DiagnosticBuilder<()>,)>>::call_once::{shim:vtable#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/library/core/src/ops/function.rs:250:5
26:     0x563da11513e8 - <alloc[86fc1011f0da8be9]::boxed::Box<dyn for<'a, 'b> core[1cc32ee8b476061a]::ops::function::FnOnce<(&'a mut rustc_errors[4a72a762f26cae1d]::diagnostic_builder::DiagnosticBuilder<'b, ()>,), Output = &'a mut rustc_errors[4a72a762f26cae1d]::diagnostic_builder::DiagnosticBuilder<'b, ()>>> as core[1cc32ee8b476061a]::ops::function::FnOnce<(&mut rustc_errors[4a72a762f26cae1d]::diagnostic_builder::DiagnosticBuilder<()>,)>>::call_once
                             at /home/matthias/vcs/github/rust_debug_assertions/library/alloc/src/boxed.rs:2007:9
27:     0x563da11513e8 - rustc_middle[6d3884defc02ee9d]::lint::struct_lint_level::struct_lint_level_impl::<alloc[86fc1011f0da8be9]::string::String>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_middle/src/lint.rs:438:9
28:     0x563da114e60b - rustc_middle[6d3884defc02ee9d]::lint::struct_lint_level::<alloc[86fc1011f0da8be9]::string::String, clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_middle/src/lint.rs:442:5
29:     0x563da12ba88e - <rustc_middle[6d3884defc02ee9d]::ty::context::TyCtxt>::struct_span_lint_hir::<rustc_span[8fc2bc2477ece13]::span_encoding::Span, alloc[86fc1011f0da8be9]::string::String, clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_middle/src/ty/context.rs:1894:9
30:     0x563da1084238 - <rustc_lint[cbe75d113ae0540b]::context::LateContext as rustc_lint[cbe75d113ae0540b]::context::LintContext>::lookup::<rustc_span[8fc2bc2477ece13]::span_encoding::Span, alloc[86fc1011f0da8be9]::string::String, clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/context.rs:1115:24
31:     0x563da1084238 - <rustc_lint[cbe75d113ae0540b]::context::LateContext as rustc_lint[cbe75d113ae0540b]::context::LintContext>::struct_span_lint::<rustc_span[8fc2bc2477ece13]::span_encoding::Span, alloc[86fc1011f0da8be9]::string::String, clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/context.rs:1017:9
32:     0x563da1084238 - clippy_utils[589fb9e96ed0da48]::diagnostics::span_lint_and_then::<rustc_lint[cbe75d113ae0540b]::context::LateContext, rustc_span[8fc2bc2477ece13]::span_encoding::Span, clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_utils/src/diagnostics.rs:148:5
33:     0x563da13628f8 - clippy_lints[6ca63caa9e712f41]::returns::emit_return_lint
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_lints/src/returns.rs:321:5
34:     0x563da13628f8 - clippy_lints[6ca63caa9e712f41]::returns::check_final_expr
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_lints/src/returns.rs:281:13
35:     0x563da1361bb0 - clippy_lints[6ca63caa9e712f41]::returns::check_block_return
36:     0x563da1361b14 - <clippy_lints[6ca63caa9e712f41]::returns::Return as rustc_lint[cbe75d113ae0540b]::passes::LateLintPass>::check_fn
                             at /home/matthias/vcs/github/rust_debug_assertions/src/tools/clippy/clippy_lints/src/returns.rs:188:17
37:     0x7f4c87c3ba46 - <rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass as rustc_lint[cbe75d113ae0540b]::passes::LateLintPass>::check_fn
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:330:21
38:     0x7f4c87c3ba46 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_fn
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:192:9
39:     0x7f4c87c3ba46 - rustc_hir[8fe631a716458333]::intravisit::walk_item::<rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass>>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_hir/src/intravisit.rs:477:13
40:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_item::{closure#0}::{closure#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:137:17
41:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass>>::with_param_env::<<rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_item::{closure#0}::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:76:9
42:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_item::{closure#0}
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:135:13
43:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass>>::with_lint_attrs::<<rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_item::{closure#0}>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:64:9
44:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_item
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_lint/src/late.rs:134:9
45:     0x7f4c87cdd886 - <rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass> as rustc_hir[8fe631a716458333]::intravisit::Visitor>::visit_nested_item
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_hir/src/intravisit.rs:239:13
46:     0x7f4c87cd8bb7 - rustc_hir[8fe631a716458333]::intravisit::walk_stmt::<rustc_lint[cbe75d113ae0540b]::late::LateContextAndPass<rustc_lint[cbe75d113ae0540b]::late::RuntimeCombinedLateLintPass>>
                             at /home/matthias/vcs/github/rust_debug_assertions/compiler/rustc_hir/src/intravisit.rs:607:33
...
...
...