ICE: segfault assigning loop to static

[matthiaskrgr]

auto-reduced (treereduce-rust):

static _X: () = loop {};

original:

static _X: () = loop {};

fn main() {}

Version information:

4019d70

Command:
crab1 -Warray-bounds -mtune=generic -march=x86-64 -O0 -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib64 -frust-incomplete-and-experimental-compiler-do-not-use

Program output

crab1: internal compiler error: Segmentation fault
0x1702eaf crash_signal
	../../gcc/toplev.cc:319
0xffec20 contains_struct_check(tree_node const*, tree_node_structure_enum, char const*, int, char const*)
	../../gcc/tree.h:4045
0xffec20 error_operand_p(tree_node const*)
	../../gcc/tree.h:4637
0xffec20 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:1896
0xffefd2 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:2196
0xfff7c8 eval_loop_expr
	../../gcc/rust/backend/rust-constexpr.cc:4894
0xfff7c8 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:2319
0x1000086 eval_statement_list
	../../gcc/rust/backend/rust-constexpr.cc:4658
0x1000086 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:2192
0xffefd2 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:2196
0xffdd4b eval_call_expression
	../../gcc/rust/backend/rust-constexpr.cc:3583
0xffef98 eval_constant_expression
	../../gcc/rust/backend/rust-constexpr.cc:2110
0x1001b90 Rust::Compile::fold_expr(tree_node*)
	../../gcc/rust/backend/rust-constexpr.cc:581
0x100e4d2 Rust::Compile::HIRCompileBase::compile_constant_item(unsigned int, Rust::TyTy::BaseType*, Rust::TyTy::BaseType*, Rust::Resolver::CanonicalPath const&, Rust::HIR::Expr&, unsigned int, unsigned int)
	../../gcc/rust/backend/rust-compile-base.cc:869
0xfd9227 Rust::Compile::CompileItem::visit(Rust::HIR::StaticItem&)
	../../gcc/rust/backend/rust-compile-item.cc:73
0xc64a14 Rust::Compile::CompileItem::compile(Rust::HIR::Item*, Rust::Compile::Context*, Rust::TyTy::BaseType*, unsigned int)
	../../gcc/rust/backend/rust-compile-item.h:37
0xc64a14 Rust::Compile::CompileCrate::go()
	../../gcc/rust/backend/rust-compile.cc:48
0xc64afb Rust::Compile::CompileCrate::Compile(Rust::HIR::Crate&, Rust::Compile::Context*)
	../../gcc/rust/backend/rust-compile.cc:41
0xc5c50b Rust::Session::compile_crate(char const*)
	../../gcc/rust/rust-session-manager.cc:733
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.

[philberty]

This is pretty stright forward to fix in backend, we already have const_context_p so we just need to check for that predicate when compiling loop exprs.