Fix corrupted GIMPLE for const-compound-assignment

gcc/rust/backend/rust-compile-expr.cc

@@ -192,9 +192,9 @@ void
 CompileExpr::visit (HIR::CompoundAssignmentExpr &expr)
 {
   auto op = expr.get_expr_type ();
-  auto lhs = CompileExpr::Compile (expr.get_lhs (), ctx);
-  auto rhs = CompileExpr::Compile (expr.get_rhs (), ctx);
-
+  tree lhs = CompileExpr::Compile (expr.get_lhs (), ctx);
+  tree rhs = CompileExpr::Compile (expr.get_rhs (), ctx);
+  tree compound_assignment = NULL_TREE;
   // this might be an operator overload situation lets check
   TyTy::FnType *fntype;
   bool is_op_overload = ctx->get_tyctx ()->lookup_operator_overload (
@@ -203,38 +203,37 @@ CompileExpr::visit (HIR::CompoundAssignmentExpr &expr)
     {
       auto lang_item_type = LangItem::CompoundAssignmentOperatorToLangItem (
 	expr.get_expr_type ());
-      auto compound_assignment
+      compound_assignment
 	= resolve_operator_overload (lang_item_type, expr, lhs, rhs,
 				     expr.get_lhs (), expr.get_rhs ());
-      ctx->add_statement (compound_assignment);
-
-      return;
     }
-
-  if (ctx->in_fn () && !ctx->const_context_p ())
+  else if (ctx->in_fn () && !ctx->const_context_p ())
     {
-      auto tmp = NULL_TREE;
+      tree tmp = NULL_TREE;
       Bvariable *receiver
 	= Backend::temporary_variable (ctx->peek_fn ().fndecl, NULL_TREE,
 				       TREE_TYPE (lhs), lhs, true,
 				       expr.get_locus (), &tmp);
-      auto check
+      tree check
 	= Backend::arithmetic_or_logical_expression_checked (op, lhs, rhs,
 							     expr.get_locus (),
 							     receiver);
       ctx->add_statement (check);
-
-      translated
+      compound_assignment
 	= Backend::assignment_statement (lhs,
 					 receiver->get_tree (expr.get_locus ()),
 					 expr.get_locus ());
     }
   else
     {
-      translated
+      tree expr_tree
 	= Backend::arithmetic_or_logical_expression (op, lhs, rhs,
 						     expr.get_locus ());
+      compound_assignment
+	= Backend::assignment_statement (lhs, expr_tree, expr.get_locus ());
     }
+  ctx->add_statement (compound_assignment);
+  translated = unit_expression (expr.get_locus ());
 }
 
 void

gcc/testsuite/rust/compile/const-compound-assignment.rs

@@ -0,0 +1,15 @@
+// { dg-options "-w -O0 -fdump-tree-gimple" }
+#![feature(no_core)]
+#![no_core]
+
+const fn test(mut x: i32) -> i32 {
+    x += 5;
+    x
+}
+
+const X: i32 = test(10);
+
+fn main() {
+    // { dg-final { scan-tree-dump-times {x = 15} 1 gimple } }
+    let x = X;
+}

gcc/testsuite/rust/execute/const-compound-assignment.rs

@@ -0,0 +1,35 @@
+// { dg-output "45\r*\n55\r*\n" }
+#![feature(no_core)]
+#![no_core]
+
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+fn dump_number(num: i32) {
+    unsafe {
+        let a = "%i\n\0";
+        let c = a as *const str as *const i8;
+        printf(c, num);
+    }
+}
+
+const fn play(b: i32) -> i32 {
+    let mut res = 0;
+    let mut i = 0;
+    while i < b {
+        res += i;
+        i += 1;
+    }
+    res
+}
+
+fn main() -> i32 {
+    const A: i32 = play(10);
+    dump_number(A);
+
+    let b: i32 = play(11);
+    dump_number(b);
+
+    0
+}