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Improve check for const initializer loop.

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From-SVN: r169003
This commit is contained in:
Ian Lance Taylor 2011-01-19 16:55:24 +00:00
parent e3e190507a
commit 036c8f3795
1 changed files with 52 additions and 12 deletions
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64
gcc/go/gofrontend/expressions.cc
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@ -2348,6 +2348,10 @@ class Const_expression : public Expression
name() const
{ return this->constant_->name(); }
// Check that the initializer does not refer to the constant itself.
void
check_for_init_loop();
protected:
Expression*
do_lower(Gogo*, Named_object*, int);
@ -2610,6 +2614,40 @@ Const_expression::do_determine_type(const Type_context* context)
}
}
// Check for a loop in which the initializer of a constant refers to
// the constant itself.
void
Const_expression::check_for_init_loop()
{
if (this->type_ != NULL && this->type_->is_error_type())
return;
if (this->seen_)
{
this->report_error(_("constant refers to itself"));
this->type_ = Type::make_error_type();
return;
}
Expression* init = this->constant_->const_value()->expr();
Find_named_object find_named_object(this->constant_);
this->seen_ = true;
Expression::traverse(&init, &find_named_object);
this->seen_ = false;
if (find_named_object.found())
{
if (this->type_ == NULL || !this->type_->is_error_type())
{
this->report_error(_("constant refers to itself"));
this->type_ = Type::make_error_type();
}
return;
}
}
// Check types of a const reference.
void
@ -2618,15 +2656,7 @@ Const_expression::do_check_types(Gogo*)
if (this->type_ != NULL && this->type_->is_error_type())
return;
Expression* init = this->constant_->const_value()->expr();
Find_named_object find_named_object(this->constant_);
Expression::traverse(&init, &find_named_object);
if (find_named_object.found())
{
this->report_error(_("constant refers to itself"));
this->type_ = Type::make_error_type();
return;
}
this->check_for_init_loop();
if (this->type_ == NULL || this->type_->is_abstract())
return;
@ -2754,9 +2784,19 @@ Find_named_object::expression(Expression** pexpr)
switch ((*pexpr)->classification())
{
case Expression::EXPRESSION_CONST_REFERENCE:
if (static_cast<Const_expression*>(*pexpr)->named_object() == this->no_)
break;
return TRAVERSE_CONTINUE;
{
Const_expression* ce = static_cast<Const_expression*>(*pexpr);
if (ce->named_object() == this->no_)
break;
// We need to check a constant initializer explicitly, as
// loops here will not be caught by the loop checking for
// variable initializers.
ce->check_for_init_loop();
return TRAVERSE_CONTINUE;
}
case Expression::EXPRESSION_VAR_REFERENCE:
if ((*pexpr)->var_expression()->named_object() == this->no_)
break;