context_test.go raw

   1  // Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
   2  // Source: ../../cmd/compile/internal/types2/context_test.go
   3  
   4  // Copyright 2021 The Go Authors. All rights reserved.
   5  // Use of this source code is governed by a BSD-style
   6  // license that can be found in the LICENSE file.
   7  
   8  package types
   9  
  10  import (
  11  	"testing"
  12  )
  13  
  14  func TestContextHashCollisions(t *testing.T) {
  15  	if debug {
  16  		t.Skip("hash collisions are expected, and would fail debug assertions")
  17  	}
  18  	// Unit test the de-duplication fall-back logic in Context.
  19  	//
  20  	// We can't test this via Instantiate because this is only a fall-back in
  21  	// case our hash is imperfect.
  22  	//
  23  	// These lookups and updates use reasonable looking types in an attempt to
  24  	// make them robust to internal type assertions, but could equally well use
  25  	// arbitrary types.
  26  
  27  	// Create some distinct origin types. nullaryP and nullaryQ have no
  28  	// parameters and are identical (but have different type parameter names).
  29  	// unaryP has a parameter.
  30  	var nullaryP, nullaryQ, unaryP Type
  31  	{
  32  		// type nullaryP = func[P any]()
  33  		tparam := NewTypeParam(NewTypeName(nopos, nil, "P", nil), &emptyInterface)
  34  		nullaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
  35  	}
  36  	{
  37  		// type nullaryQ = func[Q any]()
  38  		tparam := NewTypeParam(NewTypeName(nopos, nil, "Q", nil), &emptyInterface)
  39  		nullaryQ = NewSignatureType(nil, nil, []*TypeParam{tparam}, nil, nil, false)
  40  	}
  41  	{
  42  		// type unaryP = func[P any](_ P)
  43  		tparam := NewTypeParam(NewTypeName(nopos, nil, "P", nil), &emptyInterface)
  44  		params := NewTuple(NewParam(nopos, nil, "_", tparam))
  45  		unaryP = NewSignatureType(nil, nil, []*TypeParam{tparam}, params, nil, false)
  46  	}
  47  
  48  	ctxt := NewContext()
  49  
  50  	// Update the context with an instantiation of nullaryP.
  51  	inst := NewSignatureType(nil, nil, nil, nil, nil, false)
  52  	if got := ctxt.update("", nullaryP, []Type{Typ[Int]}, inst); got != inst {
  53  		t.Error("bad")
  54  	}
  55  
  56  	// unaryP is not identical to nullaryP, so we should not get inst when
  57  	// instantiated with identical type arguments.
  58  	if got := ctxt.lookup("", unaryP, []Type{Typ[Int]}); got != nil {
  59  		t.Error("bad")
  60  	}
  61  
  62  	// nullaryQ is identical to nullaryP, so we *should* get inst when
  63  	// instantiated with identical type arguments.
  64  	if got := ctxt.lookup("", nullaryQ, []Type{Typ[Int]}); got != inst {
  65  		t.Error("bad")
  66  	}
  67  
  68  	// ...but verify we don't get inst with different type arguments.
  69  	if got := ctxt.lookup("", nullaryQ, []Type{Typ[String]}); got != nil {
  70  		t.Error("bad")
  71  	}
  72  }
  73