gccrs: Fix ICE for invalid const capacity expression handling

When we have an invalid capacity expression we can't try to then also
const fold it as GCC will assert on invalid conversions.

Fixes #4168

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit): check for invalid capacity

gcc/testsuite/ChangeLog:

	* rust/compile/issue-4168.rs: New test.

Signed-off-by: Philip Herron <[email protected]>

Author: philberty

gcc/rust/typecheck/rust-hir-type-check-type.cc

@@ -720,19 +720,32 @@ TypeCheckType::visit (HIR::ArrayType &type)
   else
     {
       HirId size_id = type.get_size_expr ().get_mappings ().get_hirid ();
-      unify_site (size_id, TyTy::TyWithLocation (expected_ty),
-		  TyTy::TyWithLocation (capacity_type,
-					type.get_size_expr ().get_locus ()),
-		  type.get_size_expr ().get_locus ());
+      TyTy::BaseType *result
+	= unify_site (size_id, TyTy::TyWithLocation (expected_ty),
+		      TyTy::TyWithLocation (capacity_type,
+					    type.get_size_expr ().get_locus ()),
+		      type.get_size_expr ().get_locus ());
 
-      auto ctx = Compile::Context::get ();
-      tree capacity_expr = Compile::HIRCompileBase::query_compile_const_expr (
-	ctx, capacity_type, type.get_size_expr ());
-
-      const_type = new TyTy::ConstType (TyTy::ConstType::ConstKind::Value, "",
-					expected_ty, capacity_expr, {},
-					type.get_size_expr ().get_locus (),
-					size_id, size_id);
+      if (result->is<TyTy::ErrorType> ())
+	{
+	  const_type
+	    = new TyTy::ConstType (TyTy::ConstType::ConstKind::Error, "",
+				   expected_ty, error_mark_node, {},
+				   type.get_size_expr ().get_locus (), size_id,
+				   size_id);
+	}
+      else
+	{
+	  auto ctx = Compile::Context::get ();
+	  tree capacity_expr
+	    = Compile::HIRCompileBase::query_compile_const_expr (
+	      ctx, capacity_type, type.get_size_expr ());
+
+	  const_type = new TyTy::ConstType (TyTy::ConstType::ConstKind::Value,
+					    "", expected_ty, capacity_expr, {},
+					    type.get_size_expr ().get_locus (),
+					    size_id, size_id);
+	}
     }
 
   translated

gcc/testsuite/rust/compile/issue-4168.rs

@@ -0,0 +1,7 @@
+const fn add(x: usize, y: usize) -> i32 {
+    add + y
+    // { dg-error "cannot apply operator .+. to types fn .x usize,y usize,. -> i32 and usize" "" { target *-*-* } .-1 }
+}
+const ARR: [i32; add(1, 2)] = [5, 6, 1];
+// { dg-error "mismatched types, expected .usize. but got .i32. .E0308." "" { target *-*-* } .-1 }
+// { dg-error "mismatched types" "" { target *-*-* } .-2 }