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//-----------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All Rights Reserved.
//
//-----------------------------------------------------------------------------
using System;
// Visitor to search for types proxies that could not completely be
// determined by type inference. If this happens, a warning is
// generated and the proxies are instantiated in a more or less arbitrary
// fashion.
namespace Microsoft.Boogie
{
public class TypeAmbiguitySeeker : StandardVisitor {
private readonly InTypeSeeker! inTypeSeeker = new InTypeSeeker ();
private readonly TypecheckingContext! TC;
public TypeAmbiguitySeeker(TypecheckingContext! tc) {
TC = tc;
}
private void CheckTypeParams(Absy! node, TypeParamInstantiation! insts) {
foreach (TypeVariable! var in insts.FormalTypeParams) {
Type! inst = insts[var];
inTypeSeeker.FoundAmbiguity = false;
inTypeSeeker.Visit(inst);
if (inTypeSeeker.FoundAmbiguity)
TC.Warning(node,
"type parameter {0} is ambiguous, instantiating to {1}",
var, inst);
}
}
public override Expr! VisitNAryExpr(NAryExpr! node)
{
CheckTypeParams(node, (!)node.TypeParameters);
return base.VisitNAryExpr(node);
}
public override AssignLhs! VisitMapAssignLhs(MapAssignLhs! node) {
CheckTypeParams(node, (!)node.TypeParameters);
return base.VisitMapAssignLhs(node);
}
}
internal class InTypeSeeker : StandardVisitor {
internal bool FoundAmbiguity = false;
// called when an uninstantiated proxy was found
private Type! Instantiate(Type! node, Type! inst) {
FoundAmbiguity = true;
bool success = node.Unify(inst);
assert success;
return node;
}
public override Type! VisitTypeProxy(TypeProxy! node) {
if (node.ProxyFor != null)
return base.VisitTypeProxy(node);
return Instantiate(node, Type.Int);
}
public override Type! VisitMapTypeProxy(MapTypeProxy! node) {
if (node.ProxyFor != null)
return base.VisitMapTypeProxy(node);
TypeVariableSeq! typeParams = new TypeVariableSeq ();
TypeSeq! arguments = new TypeSeq ();
for (int i = 0; i < node.Arity; ++i) {
TypeVariable! param = new TypeVariable (Token.NoToken, "arg" + i);
typeParams.Add(param);
arguments.Add(param);
}
TypeVariable! result = new TypeVariable (Token.NoToken, "res");
typeParams.Add(result);
Type! instantiation = new MapType (Token.NoToken, typeParams, arguments, result);
return Instantiate(node, instantiation);
}
public override Type! VisitBvTypeProxy(BvTypeProxy! node) {
if (node.ProxyFor != null)
return base.VisitBvTypeProxy(node);
return Instantiate(node, new BvType (node.MinBits));
}
}
}
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