context_test.go

Documentation: go/types

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