ICE/Panic in clippy_lints::functions::Functions

[martinsp]

When running cargo clippy on https://github.com/Marwes/combine commit: d102591
Clippy fails with an error: "error: internal compiler error: unexpected panic"

rustc 1.34.0-nightly (4b1e39b 2019-02-05)
cargo 1.34.0-nightly (245818076 2019-01-27)
clippy 0.0.212 (3bda548 2019-02-03)

RUST_BACKTRACE=full cargo clippy --verbose

thread 'rustc' panicked at 'begin <= end (599 <= 288) when slicing `pub)
            $(#[$derive])*
            struct $type_name;
            type PartialState = (());
            $(#[$attr])*
            fn $name [$($type_params)*]($($arg : $arg_type),*)($input_type) -> $output_type
                where [$($where_clause`[...]', src/libcore/str/mod.rs:2030:5
stack backtrace:
   0:        0x112160ab3 - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::ha1ab82cbb4d6f11c
   1:        0x1121598a2 - std::sys_common::backtrace::_print::h47aa5266c1122f38
   2:        0x11215d0a6 - std::panicking::default_hook::{{closure}}::h6025bf67340fffb6
   3:        0x11215cdb1 - std::panicking::default_hook::hd2ffbd67b944c8bd
   4:        0x1107950f1 - rustc::util::common::panic_hook::hd849485fe2261c61
   5:        0x11215d8f6 - std::panicking::rust_panic_with_hook::h7a5caae104289559
   6:        0x11215d34c - std::panicking::continue_panic_fmt::hc28906cb7d739d65
   7:        0x11215d238 - rust_begin_unwind
   8:        0x112185581 - core::panicking::panic_fmt::h602d6010de239117
   9:        0x112187a80 - core::str::slice_error_fail::h0a6327d8f0dedf0c
  10:        0x10df08b63 - core::str::traits::<impl core::slice::SliceIndex<str> for core::ops::range::RangeFrom<usize>>::index::{{closure}}::h117fd6feb2ac7996
  11:        0x10df190a8 - <clippy_lints::functions::Functions as rustc::lint::LateLintPass<'a, 'tcx>>::check_fn::h34c461502c97d641
  12:        0x11044ca1d - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_fn::hab73580c424b9152
  13:        0x11079fe4a - rustc::hir::intravisit::walk_item::h90f74b5c6bc09e29
  14:        0x11044b8c0 - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item::h03734fcaf896086f
  15:        0x11044de6e - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_mod::hf8703dff7658a9c7
  16:        0x11079fb6b - rustc::hir::intravisit::walk_item::h90f74b5c6bc09e29
  17:        0x11044b8c0 - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item::h03734fcaf896086f
  18:        0x11044de6e - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_mod::hf8703dff7658a9c7
  19:        0x11079fb6b - rustc::hir::intravisit::walk_item::h90f74b5c6bc09e29
  20:        0x11044b8c0 - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item::h03734fcaf896086f
  21:        0x11044de6e - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_mod::hf8703dff7658a9c7
  22:        0x11079a730 - rustc::hir::intravisit::walk_crate::h57b0d5e573659763
  23:        0x110450646 - rustc::lint::context::check_crate::h442ccfb7bca93304
  24:        0x10e411c26 - rustc::util::common::time::h668ff82752432600
  25:        0x10e3fc533 - <std::thread::local::LocalKey<T>>::with::h3871b7c8edad0c47
  26:        0x10e3a2cae - rustc::ty::context::TyCtxt::create_and_enter::h1e37fb2793e7410a
  27:        0x10e46e243 - rustc_driver::driver::compile_input::h7031c7b83d4fdee0
  28:        0x10e41af36 - rustc_driver::run_compiler_with_pool::h3638dc7dc27c0a19
  29:        0x10e3b639e - <scoped_tls::ScopedKey<T>>::set::h78384758c2378251
  30:        0x10e419ea8 - rustc_driver::run_compiler::h09bc4bbb4983c6f9
  31:        0x10dd8eb9b - <scoped_tls::ScopedKey<T>>::set::h4f9f78ea9739d6be
  32:        0x10dd80f6d - std::sys_common::backtrace::__rust_begin_short_backtrace::he6028cd38f2f7ad6
  33:        0x11216d33e - __rust_maybe_catch_panic
  34:        0x10dd8259d - <F as alloc::boxed::FnBox<A>>::call_box::h49377575077b31ed
  35:        0x11216c2ab - std::sys::unix::thread::Thread::new::thread_start::hda92a3e89ce02644
  36:     0x7fff65034304 - _pthread_body
  37:     0x7fff6503726e - _pthread_start
query stack during panic:
end of query stack

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.34.0-nightly (4b1e39b7b 2019-02-05) running on x86_64-apple-darwin

note: compiler flags: -C debuginfo=2 -C incremental --crate-type lib

note: some of the compiler flags provided by cargo are hidden

error: Could not compile `combine`.

I have created a reduced test case (I think it triggers the same bug)

Test case

macro_rules! prepend_2 {
    (
        ( $($pub_: tt)* )
        $(#[$derive:meta])*
        struct $type_name: ident;
        $(#[$attr:meta])*
        fn $name: ident ()
        $parser: block
    ) => {
        $(#[$attr])*
        #[inline(always)]
        $($pub_)* fn $name() {
            println!("Prepended 2");
            $parser
        }
    };
}

macro_rules! prepend_1 {
    (
        $(#[$derive:meta])*
        pub struct $type_name: ident;
        $(#[$attr:meta])*
        pub fn $name: ident ()
        $parser: block
    ) => {
        prepend_2! {
            (pub)
            $(#[$derive])*
            struct $type_name;
            fn $name () {
                println!("Prepended 1");
                $parser
            }
        }
    };
}

prepend_1! {
    #[derive(Copy, Clone)]
    pub struct StructOne;
    /// Prints "Hello World!".
    pub fn say_hello() {
        println!("Hello World!");
    }
}

fn main() {
    say_hello();
}

cargo is compiling and running the code

cargo run

Prepended 2
Prepended 1
Hello World!

Running clippy fails with a panic

RUST_BACKTRACE=full cargo clippy --verbose

thread 'rustc' panicked at 'begin <= end (36 <= 0) when slicing `}
    };
}

macro_rules! prepend_1 {
    (
        $(#[$derive:meta])*
        pub struct $type_name: ident;
        $(#[$attr:meta])*
        pub fn $name: ident ()
        $parser: block
    ) => {
        prepend_2! {
            (pub`', src/libcore/str/mod.rs:2030:5
stack backtrace:
   0:        0x10fafdab3 - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::ha1ab82cbb4d6f11c
   1:        0x10faf68a2 - std::sys_common::backtrace::_print::h47aa5266c1122f38
   2:        0x10fafa0a6 - std::panicking::default_hook::{{closure}}::h6025bf67340fffb6
   3:        0x10faf9db1 - std::panicking::default_hook::hd2ffbd67b944c8bd
   4:        0x10e1260f1 - rustc::util::common::panic_hook::hd849485fe2261c61
   5:        0x10fafa8f6 - std::panicking::rust_panic_with_hook::h7a5caae104289559
   6:        0x10fafa34c - std::panicking::continue_panic_fmt::hc28906cb7d739d65
   7:        0x10fafa238 - rust_begin_unwind
   8:        0x10fb22581 - core::panicking::panic_fmt::h602d6010de239117
   9:        0x10fb24a80 - core::str::slice_error_fail::h0a6327d8f0dedf0c
  10:        0x10b89cb63 - core::str::traits::<impl core::slice::SliceIndex<str> for core::ops::range::RangeFrom<usize>>::index::{{closure}}::h117fd6feb2ac7996
  11:        0x10b8ad0a8 - <clippy_lints::functions::Functions as rustc::lint::LateLintPass<'a, 'tcx>>::check_fn::h34c461502c97d641
  12:        0x10dddda1d - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_fn::hab73580c424b9152
  13:        0x10e130e4a - rustc::hir::intravisit::walk_item::h90f74b5c6bc09e29
  14:        0x10dddc8c0 - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item::h03734fcaf896086f
  15:        0x10dddee6e - <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_mod::hf8703dff7658a9c7
  16:        0x10e12b730 - rustc::hir::intravisit::walk_crate::h57b0d5e573659763
  17:        0x10dde1646 - rustc::lint::context::check_crate::h442ccfb7bca93304
  18:        0x10bda7c26 - rustc::util::common::time::h668ff82752432600
  19:        0x10bd92533 - <std::thread::local::LocalKey<T>>::with::h3871b7c8edad0c47
  20:        0x10bd38cae - rustc::ty::context::TyCtxt::create_and_enter::h1e37fb2793e7410a
  21:        0x10be04243 - rustc_driver::driver::compile_input::h7031c7b83d4fdee0
  22:        0x10bdb0f36 - rustc_driver::run_compiler_with_pool::h3638dc7dc27c0a19
  23:        0x10bd4c39e - <scoped_tls::ScopedKey<T>>::set::h78384758c2378251
  24:        0x10bdafea8 - rustc_driver::run_compiler::h09bc4bbb4983c6f9
  25:        0x10b722b9b - <scoped_tls::ScopedKey<T>>::set::h4f9f78ea9739d6be
  26:        0x10b714f6d - std::sys_common::backtrace::__rust_begin_short_backtrace::he6028cd38f2f7ad6
  27:        0x10fb0a33e - __rust_maybe_catch_panic
  28:        0x10b71659d - <F as alloc::boxed::FnBox<A>>::call_box::h49377575077b31ed
  29:        0x10fb092ab - std::sys::unix::thread::Thread::new::thread_start::hda92a3e89ce02644
  30:     0x7fff65034304 - _pthread_body
  31:     0x7fff6503726e - _pthread_start
query stack during panic:
end of query stack

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.34.0-nightly (4b1e39b7b 2019-02-05) running on x86_64-apple-darwin

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

[phansch]

Thanks for the report and testcase!

[jfirebaugh]

Further reduced:

macro_rules! a {
    ( $pub:tt $($attr:tt)* ) => {
        $($attr)* $pub fn say_hello() {}
    };
}

macro_rules! b {
    () => { a! { pub } };
}

b! {}

This crashes on the playground, but for some reason I couldn't reproduce locally.

[mati865]

@jfirebaugh it does panic with nightly-2019-02-07:

thread 'rustc' panicked at 'begin <= end (28 <= 0) when slicing `}
    };
}

macro_rules! b {
    () => { a! { pub`', src/libcore/str/mod.rs:2030:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:39
   1: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:70
   2: std::panicking::default_hook::{{closure}}
             at src/libstd/sys_common/backtrace.rs:58
             at src/libstd/panicking.rs:200
   3: std::panicking::default_hook
             at src/libstd/panicking.rs:215
   4: rustc::util::common::panic_hook
   5: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:482
   6: std::panicking::continue_panic_fmt
             at src/libstd/panicking.rs:385
   7: rust_begin_unwind
             at src/libstd/panicking.rs:312
   8: core::panicking::panic_fmt
             at src/libcore/panicking.rs:85
   9: core::str::slice_error_fail
             at src/libcore/str/mod.rs:0
  10: core::str::traits::<impl core::slice::SliceIndex<str> for core::ops::range::RangeFrom<usize>>::index::{{closure}}
  11: <clippy_lints::functions::Functions as rustc::lint::LateLintPass<'a, 'tcx>>::check_fn
  12: <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_fn
  13: rustc::hir::intravisit::walk_item
  14: <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_item
  15: <rustc::lint::context::LateContext<'a, 'tcx> as rustc::hir::intravisit::Visitor<'tcx>>::visit_mod
  16: rustc::hir::intravisit::walk_crate
  17: rustc::lint::context::check_crate
  18: rustc_driver::driver::phase_3_run_analysis_passes::{{closure}}::{{closure}}
  19: rustc::util::common::time
  20: <std::thread::local::LocalKey<T>>::with
  21: rustc::ty::context::TyCtxt::create_and_enter
  22: rustc_driver::driver::compile_input
  23: <scoped_tls::ScopedKey<T>>::set
  24: rustc_driver::run_compiler
  25: <scoped_tls::ScopedKey<T>>::set
query stack during panic:
end of query stack