[clang] treat constexpr as const too

Summary: The frontend replaces global variables that are constant with their values as a quick hack to improve the precision of the analysis. This should apply to `constexpr` too.

Reviewed By: dulmarod

Differential Revision: D4058097

fbshipit-source-id: be4fea6

infer/src/clang/cTrans.ml

@@ -631,8 +631,11 @@ struct
               when not (General_utils.is_cpp_translation context.translation_unit_context) ->
                 (* Do not convert a global struct to a local because SIL
                    values do not include structs, they must all be heap-allocated  *)
-                false, None
-            | _ -> vdi.vdi_is_global && qual_type.qt_is_const, vdi.vdi_init_expr)
+                (false, None)
+            | _ ->
+                (vdi.vdi_is_global && (vdi.vdi_is_const_expr || qual_type.qt_is_const),
+                 vdi.vdi_init_expr)
+          )
         | _ -> false, None in
       if is_global_const then
         init_expr_trans trans_state (var_exp, typ) stmt_info init_expr