[COMMITTED] gccrs: Static Items must be const evaluated

[Arthur Cohen <arthur.cohen@embecosm.com>]

From: Philip Herron <philip.herron@embecosm.com>

Statics like constants need to have a singular value they are not functions
to be lazy evaluated. So to evaluate a block expr we can just reuse our
const code to resolve this to a singular value.

gcc/rust/ChangeLog:

	* backend/rust-compile-item.cc (CompileItem::visit): Const evaluate
	static item expressions.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/rust/backend/rust-compile-item.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/backend/rust-compile-item.cc b/gcc/rust/backend/rust-compile-item.cc
index 634b983a771..d1cdc3b6698 100644
--- a/gcc/rust/backend/rust-compile-item.cc
+++ b/gcc/rust/backend/rust-compile-item.cc
@@ -43,13 +43,18 @@ CompileItem::visit (HIR::StaticItem &var)
   rust_assert (ok);
 
   tree type = TyTyResolveCompile::compile (ctx, resolved_type);
-  tree value = CompileExpr::Compile (var.get_expr (), ctx);
 
   const Resolver::CanonicalPath *canonical_path = nullptr;
   ok = ctx->get_mappings ()->lookup_canonical_path (
     var.get_mappings ().get_nodeid (), &canonical_path);
   rust_assert (ok);
 
+  HIR::Expr *const_value_expr = var.get_expr ();
+  ctx->push_const_context ();
+  tree value = compile_constant_item (ctx, resolved_type, canonical_path,
+				      const_value_expr, var.get_locus ());
+  ctx->pop_const_context ();
+
   std::string name = canonical_path->get ();
   std::string asm_name = ctx->mangle_item (resolved_type, *canonical_path);
 
-- 
2.39.1