Passing a mutable reference of a closure to a polymorphic function causes a panic

[coord-e]

9e92551

fn next<F>(f: &mut F) {}

fn main() {
    let mut f = || {};
    next(&mut f);
}

thread 'rustc' panicked at src/analyze/basic_block.rs:622:9:
assertion failed: place.projection.last() == Some(&mir::ProjectionElem::Deref)
stack backtrace:
   0: rust_begin_unwind
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/library/std/src/panicking.rs:645:5
   1: core::panicking::panic_fmt
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/library/core/src/panicking.rs:72:14
   2: core::panicking::panic
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/library/core/src/panicking.rs:145:5
   3: thrust::analyze::basic_block::Analyzer::elaborate_place_for_borrow
             at ./src/analyze/basic_block.rs:622:9
   4: thrust::analyze::basic_block::Analyzer::mutable_borrow
             at ./src/analyze/basic_block.rs:659:21
   5: thrust::analyze::basic_block::Analyzer::analyze_assignment
             at ./src/analyze/basic_block.rs:694:23
   6: thrust::analyze::basic_block::Analyzer::analyze_statements
             at ./src/analyze/basic_block.rs:732:21
   7: thrust::analyze::basic_block::Analyzer::run
             at ./src/analyze/basic_block.rs:1126:9
   8: thrust::analyze::local_def::Analyzer::analyze_basic_blocks
             at ./src/analyze/local_def.rs:663:13
   9: thrust::analyze::local_def::Analyzer::run
             at ./src/analyze/local_def.rs:796:9
  10: thrust::analyze::crate_::Analyzer::analyze_local_defs
             at ./src/analyze/crate_.rs:135:13
  11: thrust::analyze::crate_::Analyzer::run
             at ./src/analyze/crate_.rs:240:9
  12: <thrust_rustc::CompilerCalls as rustc_driver_impl::Callbacks>::after_analysis::{{closure}}
             at ./src/main.rs:54:13
  13: rustc_middle::ty::context::GlobalCtxt::enter::{{closure}}
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/compiler/rustc_middle/src/ty/context.rs:649:37
  14: rustc_middle::ty::context::tls::enter_context::{{closure}}
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/compiler/rustc_middle/src/ty/context/tls.rs:82:9
  15: std::thread::local::LocalKey<T>::try_with
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/library/std/src/thread/local.rs:284:16
  16: std::thread::local::LocalKey<T>::with
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/library/std/src/thread/local.rs:260:9
  17: rustc_middle::ty::context::tls::enter_context
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/compiler/rustc_middle/src/ty/context/tls.rs:79:9
  18: rustc_middle::ty::context::GlobalCtxt::enter
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/compiler/rustc_middle/src/ty/context.rs:649:9
  19: rustc_interface::queries::QueryResult<&rustc_middle::ty::context::GlobalCtxt>::enter
             at /rustc/9c3ad802d9b9633d60d3a74668eb1be819212d34/compiler/rustc_interface/src/queries.rs:71:9
  20: <thrust_rustc::CompilerCalls as rustc_driver_impl::Callbacks>::after_analysis
             at ./src/main.rs:51:9
  21: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[coord-e]

// MIR for `main` after runtime-optimized

fn main() -> () {
    let mut _0: ();
    let mut _1: {closure@closure_field_2.rs:4:17: 4:19};
    let _2: ();
    let mut _3: &mut {closure@closure_field_2.rs:4:17: 4:19};
    scope 1 {
        debug f => const ZeroSized: {closure@closure_field_2.rs:4:17: 4:19};
    }

    bb0: {
        _3 = &mut _1;
        _2 = next::<{closure@closure_field_2.rs:4:17: 4:19}>(_3) -> [return: bb1, unwind continue];
    }

    bb1: {
        return;
    }
}

[coord-e]

diff --git a/src/analyze/local_def.rs b/src/analyze/local_def.rs
index 60bffa9..808973a 100644
--- a/src/analyze/local_def.rs
+++ b/src/analyze/local_def.rs
@@ -592,7 +592,9 @@ impl<'tcx, 'ctx> Analyzer<'tcx, 'ctx> {
                 let mut_locals = self.mut_locals(data.visitable(statement_index));
                 tracing::info!(?init_locals, ?mut_locals, ?statement_index, ?block, stmt = ?data.statements.get(statement_index));
                 for mut_local in mut_locals.iter() {
-                    if init_locals.contains(&mut_local) {
+                    let mut_local_ty = mir_ty::ParamEnv::reveal_all().and(self.body.local_decls[mut_local].ty);
+                    let is_zst = self.tcx.layout_of(mut_local_ty).map(|l| l.is_zst()).unwrap_or(false);
+                    if init_locals.contains(&mut_local) || is_zst {
                         self.body.local_decls[mut_local].mutability = mir::Mutability::Mut;
                         tracing::info!(?mut_local, ?statement_index, ?block, "marking mut");
                     }