Fix SOA entity usage error on `-vet`

examples/demo/demo.odin

@@ -35,7 +35,7 @@ the_basics :: proc() {
 		// A comment
 
 		my_integer_variable: int; // A comment for documentaton
-		
+
 		// Multi-line comments begin with /* and end with */. Multi-line comments can
 		// also be nested (unlike in C):
 		/*
@@ -113,7 +113,7 @@ the_basics :: proc() {
 		// Constants can be explicitly typed like a variable declaration:
 		Y : int : 123;
 		Z :: Y + 7; // constant computations are possible
-		
+
 		_ = my_integer_variable;
 		_ = x;
 	}
@@ -213,8 +213,8 @@ control_flow :: proc() {
 
 		// The iterated values are copies and cannot be written to.
 		// The following idiom is useful for iterating over a container in a by-reference manner:
-		for _, i in some_slice {
-			some_slice[i] = (i+1)*(i+1);
+		for _, idx in some_slice {
+			some_slice[idx] = (idx+1)*(idx+1);
 		}
 
 
@@ -827,6 +827,8 @@ implicit_context_system :: proc() {
 		// default unless explicitly specified otherwise
 		china_grove := new(int);
 		free(china_grove);
+
+		_ = c;
 	}
 
 	my_custom_allocator :: mem.nil_allocator;

src/check_type.cpp

@@ -2781,6 +2781,7 @@ Type *make_soa_struct_slice(CheckerContext *ctx, Ast *array_typ_expr, Ast *elem_
 				new_field->flags |= EntityFlag_SoaPtrField;
 				soa_struct->Struct.fields[i] = new_field;
 				add_entity(ctx->checker, scope, nullptr, new_field);
+				add_entity_use(ctx, nullptr, new_field);
 			} else {
 				soa_struct->Struct.fields[i] = old_field;
 			}
@@ -3056,6 +3057,7 @@ bool check_type_internal(CheckerContext *ctx, Ast *e, Type **type, Type *named_t
 								Entity *new_field = alloc_entity_field(scope, old_field->token, array_type, false, old_field->Variable.field_src_index);
 								soa_struct->Struct.fields[i] = new_field;
 								add_entity(ctx->checker, scope, nullptr, new_field);
+								add_entity_use(ctx, nullptr, new_field);
 							} else {
 								soa_struct->Struct.fields[i] = old_field;
 							}