segfault with attr on macro decl

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auto-reduced (treereduce-rust):

//@compile-flags: -frust-incomplete-and-experimental-compiler-do-not-use
#![no_core]

#[coverage(off)]

macro_rules! decl_foo {
    () => {
        static FOO: u32 = 0;
    };
}

decl_foo!();

original:

#![feature(no_core)]
#![no_core]
//@ ignore-lldb

// Test that static debug info is not collapsed with #[collapse_debuginfo(external)]

//@ compile-flags:-g
//@ ignore-backends: gcc

// === GDB TESTS ===================================================================================

//@ gdb-command:info line collapse_debuginfo_static_external::FOO
//@ gdb-check:[...]Line 16[...]

#[coverage(off)] //~ ERROR multiple `coverage` attributes
#[coverage(off)]
macro_rules! decl_foo {
    () => {
        static FOO: u32 = 0;
    };
}

decl_foo!();

fn main() {
    let mut res = Vec::new();
    let s1 = vec![1, 2, 3, 4];
    res.extend_from_slice(&s1);
    res.extend_from_slice(&s1);
    res.extend_from_slice(&s1);
    res.extend_from_slice(&s1);
    res
}

Version information:

1a9102843099b18f9dbb6b5e979436f6c4566f1c

Command:
/home/matthias/vcs/github/gccrs/gccrs-build/gcc/crab1 -frust-incomplete-and-experimental-compiler-do-not-use

Program output

/tmp/icemaker_global_tempdir.BuEqbgOPwAlh/rustc_testrunner_tmpdir_reporting.VYvgZlGkeT2Q/mvce.rs:3:3: error: macro not found
    3 | #[coverage(off)]
      |   ^~~~~~~~
crab1: internal compiler error: Segmentation fault
0x3097ef9 internal_error(char const*, ...)
	../../gcc/diagnostic-global-context.cc:787
0x19c085f crash_signal
	../../gcc/toplev.cc:325
0xe98330 Rust::MacroExpander::expand_decl_macro(unsigned long, Rust::AST::MacroInvocData&, Rust::AST::MacroRulesDefinition&, Rust::AST::InvocKind)
	../../gcc/rust/expand/rust-macro-expand.cc:43
0xe991eb Rust::MacroExpander::expand_invoc(Rust::AST::MacroInvocation&, Rust::AST::InvocKind)
	../../gcc/rust/expand/rust-macro-expand.cc:333
0xea7f5a void Rust::ExpandVisitor::expand_macro_children<std::vector<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> >, std::allocator<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> > > >, std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> > >(std::vector<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> >, std::allocator<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> > > >&, std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> > (Rust::AST::SingleASTNode::*)())
	../../gcc/rust/expand/rust-expand-visitor.h:154
0xea7f5a Rust::ExpandVisitor::expand_inner_items(std::vector<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> >, std::allocator<std::unique_ptr<Rust::AST::Item, std::default_delete<Rust::AST::Item> > > >&)
	../../gcc/rust/expand/rust-expand-visitor.cc:243
0xe65cdb Rust::Session::expansion(Rust::AST::Crate&, Rust::Resolver2_0::NameResolutionContext&)
	../../gcc/rust/rust-session-manager.cc:1039
0xe73f9b Rust::Session::compile_crate(char const*)
	../../gcc/rust/rust-session-manager.cc:698
/home/matthias/vcs/github/gccrs/gccrs-build/gcc/crab1 /tmp/icemaker_global_tempdir.BuEqbgOPwAlh/rustc_testrunner_tmpdir_reporting.VYvgZlGkeT2Q/mvce.rs -o/tmp/icemaker_global_tempdir.BuEqbgOPwAlh/rustc_testrunner_tmpdir_reporting.VYvgZlGkeT2Q/binaryname -frust-incomplete-and-experimental-compiler-do-not-use
Please submit a full bug report, with preprocessed source (by using -freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

Start with gcc/rust/expand/rust-macro-expand.cc at Rust::MacroExpander::expand_decl_macro, identified by the backtrace, and reproduce the crash with the reduced /tmp/im/a.rs case and its compile flag. Done means the #[coverage(off)] macro declaration produces a diagnostic or continues without a segmentation fault.

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