compiler: If a variable that is only set, give not used error.

From-SVN: r212876

diff --git a/gcc/go/gofrontend/parse.cc b/gcc/go/gofrontend/parse.cc
index d7d3a072040ef14bfe147e1108ad1bd6da109560..90f1a3405c116bee73d4879d5c3b2fcb047d1e72 100644 (file)
--- a/gcc/go/gofrontend/parse.cc
+++ b/gcc/go/gofrontend/parse.cc
@@ -2115,8 +2115,8 @@ Parse::simple_var_decl_or_assignment(const std::string& name,
          for (Typed_identifier_list::const_iterator p = til.begin();
               p != til.end();
               ++p)
-           exprs->push_back(this->id_to_expression(p->name(),
-                                                   p->location()));
+           exprs->push_back(this->id_to_expression(p->name(), p->location(),
+                                                   true));
 
          Expression_list* more_exprs =
            this->expression_list(NULL, true, may_be_composite_lit);
@@ -2509,7 +2509,10 @@ Parse::operand(bool may_be_sink, bool* is_parenthesized)
            }
          case Named_object::NAMED_OBJECT_VAR:
          case Named_object::NAMED_OBJECT_RESULT_VAR:
-           this->mark_var_used(named_object);
+           // Any left-hand-side can be a sink, so if this can not be
+           // a sink, then it must be a use of the variable.
+           if (!may_be_sink)
+             this->mark_var_used(named_object);
            return Expression::make_var_reference(named_object, location);
          case Named_object::NAMED_OBJECT_SINK:
            if (may_be_sink)
@@ -2724,7 +2727,7 @@ Parse::composite_lit(Type* type, int depth, Location location)
              Gogo* gogo = this->gogo_;
              val = this->id_to_expression(gogo->pack_hidden_name(identifier,
                                                                  is_exported),
-                                          location);
+                                          location, false);
              is_name = true;
            }
          else
@@ -3241,7 +3244,8 @@ Parse::call(Expression* func)
 // Return an expression for a single unqualified identifier.
 
 Expression*
-Parse::id_to_expression(const std::string& name, Location location)
+Parse::id_to_expression(const std::string& name, Location location,
+                       bool is_lhs)
 {
   Named_object* in_function;
   Named_object* named_object = this->gogo_->lookup(name, &in_function);
@@ -3260,7 +3264,8 @@ Parse::id_to_expression(const std::string& name, Location location)
       return Expression::make_const_reference(named_object, location);
     case Named_object::NAMED_OBJECT_VAR:
     case Named_object::NAMED_OBJECT_RESULT_VAR:
-      this->mark_var_used(named_object);
+      if (!is_lhs)
+       this->mark_var_used(named_object);
       return Expression::make_var_reference(named_object, location);
     case Named_object::NAMED_OBJECT_SINK:
       return Expression::make_sink(location);
@@ -5025,7 +5030,7 @@ Parse::send_or_recv_stmt(bool* is_send, Expression** channel, Expression** val,
 
          *val = this->id_to_expression(gogo->pack_hidden_name(recv_var,
                                                               is_rv_exported),
-                                       recv_var_loc);
+                                       recv_var_loc, true);
          saw_comma = true;
        }
       else
@@ -5727,6 +5732,13 @@ Parse::verify_not_sink(Expression* expr)
       error_at(expr->location(), "cannot use _ as value");
       expr = Expression::make_error(expr->location());
     }
+
+  // If this can not be a sink, and it is a variable, then we are
+  // using the variable, not just assigning to it.
+  Var_expression* ve = expr->var_expression();
+  if (ve != NULL)
+    this->mark_var_used(ve->named_object());
+
   return expr;
 }
 

diff --git a/gcc/go/gofrontend/parse.h b/gcc/go/gofrontend/parse.h
index 99e0eeebc246f76c60b125c4b45c7c949051638f..3a7bbd53700775dd467a3c9ab902b7980ff2ad48 100644 (file)
--- a/gcc/go/gofrontend/parse.h
+++ b/gcc/go/gofrontend/parse.h
@@ -236,7 +236,7 @@ class Parse
                         bool* is_type_switch, bool* is_parenthesized);
   Type* reassociate_chan_direction(Channel_type*, Location);
   Expression* qualified_expr(Expression*, Location);
-  Expression* id_to_expression(const std::string&, Location);
+  Expression* id_to_expression(const std::string&, Location, bool);
   void statement(Label*);
   bool statement_may_start_here();
   void labeled_stmt(const std::string&, Location);

diff --git a/gcc/testsuite/go.test/test/shift1.go b/gcc/testsuite/go.test/test/shift1.go
index 44a3792c4fa7ee2cd57e7e7dfe379eb69ef1033c..04f5321b73f21d2894d01cc5ec77ce9e74569a91 100644 (file)
--- a/gcc/testsuite/go.test/test/shift1.go
+++ b/gcc/testsuite/go.test/test/shift1.go
@@ -238,4 +238,6 @@ func _() {
        z = (1. << s) << (1 << s)    // ERROR "non-integer|type complex128"
        z = (1. << s) << (1. << s)   // ERROR "non-integer|type complex128"
        z = (1.1 << s) << (1.1 << s) // ERROR "invalid|truncated|complex128"
+
+       _, _, _ = x, y, z
 }