Closed
Description
An unexpected compiler panic occurs when parsing a macro that casts without parentheses surrounding the cast.
I tried this code:
macro_rules! is_plainly_printable {
($i:ident) => {
$i as u32 < 0
};
}
fn main() {
let c = 'a';
is_plainly_printable!(c);
}
I expected to see this happen:
error: `<` is interpreted as a start of generic arguments for `u32`, not a comparison
--> src/main.rs:9:13
|
9 | c as u32 < 0;
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
help: if you want to compare the casted value then write:
| (c as u32) < 0;
Instead, this happened: the compiler panicked
Compiling compbug v0.1.0 (file:///home/kefin/stuf/docs/compbug)
Running `rustc --crate-name compbug src/main.rs --crate-type bin --emit=dep-info,link -C debuginfo=2 -C metadata=fa650156f9d48338 -C extra-filename=-fa650156f9d48338 --out-dir /home/kefin/stuf/docs/compbug/target/debug/deps -L dependency=/home/kefin/stuf/docs/compbug/target/debug/deps`
error: `<` is interpreted as a start of generic arguments for `u32`, not a comparison
--> src/main.rs:3:15
|
3 | $i as u32 < 0
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
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 1.20.0-nightly (f590a44ce 2017-06-27) running on x86_64-unknown-linux-gnu
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: IllFormedSpan(Span { lo: BytePos(125), hi: BytePos(64), ctxt: #0 })', /checkout/src/libcore/result.rs:860
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: Could not compile `compbug`.
Caused by:
process didn't exit successfully: `rustc --crate-name compbug src/main.rs --crate-type bin --emit=dep-info,link -C debuginfo=2 -C metadata=fa650156f9d48338 -C extra-filename=-fa650156f9d48338 --out-dir /home/kefin/stuf/docs/compbug/target/debug/deps -L dependency=/home/kefin/stuf/docs/compbug/target/debug/deps` (exit code: 101)
Meta
rustc --version --verbose:
rustc 1.20.0-nightly (f590a44ce 2017-06-27)
binary: rustc
commit-hash: f590a44ce61888c78b9044817d8b798db5cd2ffd
commit-date: 2017-06-27
host: x86_64-unknown-linux-gnu
release: 1.20.0-nightly
LLVM version: 4.0
Backtrace:
Compiling compbug v0.1.0 (file:///home/kefin/stuf/docs/compbug)
Running `rustc --crate-name compbug src/main.rs --crate-type bin --emit=dep-info,link -C debuginfo=2 -C metadata=fa650156f9d48338 -C extra-filename=-fa650156f9d48338 --out-dir /home/kefin/stuf/docs/compbug/target/debug/deps -L dependency=/home/kefin/stuf/docs/compbug/target/debug/deps`
error: `<` is interpreted as a start of generic arguments for `u32`, not a comparison
--> src/main.rs:3:15
|
3 | $i as u32 < 0
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
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 1.20.0-nightly (f590a44ce 2017-06-27) running on x86_64-unknown-linux-gnu
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: IllFormedSpan(Span { lo: BytePos(125), hi: BytePos(64), ctxt: #0 })', /checkout/src/libcore/result.rs:860
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at /checkout/src/libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at /checkout/src/libstd/sys_common/backtrace.rs:60
at /checkout/src/libstd/panicking.rs:355
3: std::panicking::default_hook
at /checkout/src/libstd/panicking.rs:365
4: std::panicking::rust_panic_with_hook
at /checkout/src/libstd/panicking.rs:549
5: std::panicking::begin_panic
at /checkout/src/libstd/panicking.rs:511
6: std::panicking::begin_panic_fmt
at /checkout/src/libstd/panicking.rs:495
7: rust_begin_unwind
at /checkout/src/libstd/panicking.rs:471
8: core::panicking::panic_fmt
at /checkout/src/libcore/panicking.rs:71
9: core::result::unwrap_failed
10: <rustc_errors::emitter::EmitterWriter as rustc_errors::emitter::Emitter>::emit
11: rustc_errors::diagnostic_builder::DiagnosticBuilder::emit
12: syntax::parse::parser::Parser::parse_assoc_op_as
13: syntax::parse::parser::Parser::parse_assoc_expr_with
14: syntax::parse::parser::Parser::parse_stmt_without_recovery::{{closure}}
15: syntax::parse::parser::Parser::parse_stmt_without_recovery
16: syntax::parse::parser::Parser::parse_stmt_
17: syntax::parse::parser::Parser::parse_full_stmt
18: syntax::ext::expand::<impl syntax::parse::parser::Parser<'a>>::parse_expansion
19: syntax::ext::tt::macro_rules::ParserAnyMacro::make
20: syntax::ext::expand::<impl syntax::ext::base::MacResult for syntax::ext::tt::macro_rules::ParserAnyMacro<'a>>::make_stmts
21: syntax::ext::expand::ExpansionKind::make_from
22: syntax::ext::expand::MacroExpander::expand_bang_invoc
23: syntax::ext::expand::MacroExpander::expand
24: syntax::ext::expand::MacroExpander::expand_crate
25: rustc_driver::driver::phase_2_configure_and_expand::{{closure}}
26: rustc_driver::driver::phase_2_configure_and_expand
27: rustc_driver::driver::compile_input
28: rustc_driver::run_compiler
error: Could not compile `compbug`.
Caused by:
process didn't exit successfully: `rustc --crate-name compbug src/main.rs --crate-type bin --emit=dep-info,link -C debuginfo=2 -C metadata=fa650156f9d48338 -C extra-filename=-fa650156f9d48338 --out-dir /home/kefin/stuf/docs/compbug/target/debug/deps -L dependency=/home/kefin/stuf/docs/compbug/target/debug/deps` (exit code: 101)