public bool CheckInvariantMeaningInBlock (string name, Expression e, Location loc)
{
Block b = this;
IKnownVariable kvi = b.Explicit.GetKnownVariable (name);
while (kvi == null) {
b = b.Explicit.Parent;
if (b == null)
return true;
kvi = b.Explicit.GetKnownVariable (name);
}
if (kvi.Block == b)
return true;
// Is kvi.Block nested inside 'b'
if (b.Explicit != kvi.Block.Explicit) {
//
// If a variable by the same name it defined in a nested block of this
// block, we violate the invariant meaning in a block.
//
if (b == this) {
Toplevel.Report.SymbolRelatedToPreviousError (kvi.Location, name);
Toplevel.Report.Error (135, loc, "`{0}' conflicts with a declaration in a child block", name);
return false;
}
//
// It's ok if the definition is in a nested subblock of b, but not
// nested inside this block -- a definition in a sibling block
// should not affect us.
//
return true;
}
//
// Block 'b' and kvi.Block are the same textual block.
// However, different variables are extant.
//
// Check if the variable is in scope in both blocks. We use
// an indirect check that depends on AddVariable doing its
// part in maintaining the invariant-meaning-in-block property.
//
if (e is VariableReference || (e is Constant && b.GetLocalInfo (name) != null))
return true;
if (this is ToplevelBlock) {
Toplevel.Report.SymbolRelatedToPreviousError (kvi.Location, name);
e.Error_VariableIsUsedBeforeItIsDeclared (Toplevel.Report, name);
return false;
}
//
// Even though we detected the error when the name is used, we
// treat it as if the variable declaration was in error.
//
Toplevel.Report.SymbolRelatedToPreviousError (loc, name);
Error_AlreadyDeclared (kvi.Location, name, "parent or current");
return false;
}
