named_test.go

Documentation: go/types

     1  // Copyright 2022 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package types_test
     6  
     7  import (
     8  	"go/ast"
     9  	"go/token"
    10  	"testing"
    11  
    12  	. "go/types"
    13  )
    14  
    15  func BenchmarkNamed(b *testing.B) {
    16  	const src = `
    17  package p
    18  
    19  type T struct {
    20  	P int
    21  }
    22  
    23  func (T) M(int) {}
    24  func (T) N() (i int) { return }
    25  
    26  type G[P any] struct {
    27  	F P
    28  }
    29  
    30  func (G[P]) M(P) {}
    31  func (G[P]) N() (p P) { return }
    32  
    33  type Inst = G[int]
    34  	`
    35  	pkg := mustTypecheck(src, nil, nil)
    36  
    37  	var (
    38  		T        = pkg.Scope().Lookup("T").Type()
    39  		G        = pkg.Scope().Lookup("G").Type()
    40  		SrcInst  = pkg.Scope().Lookup("Inst").Type()
    41  		UserInst = mustInstantiate(b, G, Typ[Int])
    42  	)
    43  
    44  	tests := []struct {
    45  		name string
    46  		typ  Type
    47  	}{
    48  		{"nongeneric", T},
    49  		{"generic", G},
    50  		{"src instance", SrcInst},
    51  		{"user instance", UserInst},
    52  	}
    53  
    54  	b.Run("Underlying", func(b *testing.B) {
    55  		for _, test := range tests {
    56  			b.Run(test.name, func(b *testing.B) {
    57  				// Access underlying once, to trigger any lazy calculation.
    58  				_ = test.typ.Underlying()
    59  				b.ResetTimer()
    60  				for i := 0; i < b.N; i++ {
    61  					_ = test.typ.Underlying()
    62  				}
    63  			})
    64  		}
    65  	})
    66  
    67  	b.Run("NewMethodSet", func(b *testing.B) {
    68  		for _, test := range tests {
    69  			b.Run(test.name, func(b *testing.B) {
    70  				// Access underlying once, to trigger any lazy calculation.
    71  				_ = NewMethodSet(test.typ)
    72  				b.ResetTimer()
    73  				for i := 0; i < b.N; i++ {
    74  					_ = NewMethodSet(test.typ)
    75  				}
    76  			})
    77  		}
    78  	})
    79  }
    80  
    81  func mustInstantiate(tb testing.TB, orig Type, targs ...Type) Type {
    82  	inst, err := Instantiate(nil, orig, targs, true)
    83  	if err != nil {
    84  		tb.Fatal(err)
    85  	}
    86  	return inst
    87  }
    88  
    89  // Test that types do not expand infinitely, as in go.dev/issue/52715.
    90  func TestFiniteTypeExpansion(t *testing.T) {
    91  	const src = `
    92  package p
    93  
    94  type Tree[T any] struct {
    95  	*Node[T]
    96  }
    97  
    98  func (*Tree[R]) N(r R) R { return r }
    99  
   100  type Node[T any] struct {
   101  	*Tree[T]
   102  }
   103  
   104  func (Node[Q]) M(Q) {}
   105  
   106  type Inst = *Tree[int]
   107  `
   108  
   109  	fset := token.NewFileSet()
   110  	f := mustParse(fset, src)
   111  	pkg := NewPackage("p", f.Name.Name)
   112  	if err := NewChecker(nil, fset, pkg, nil).Files([]*ast.File{f}); err != nil {
   113  		t.Fatal(err)
   114  	}
   115  
   116  	firstFieldType := func(n *Named) *Named {
   117  		return n.Underlying().(*Struct).Field(0).Type().(*Pointer).Elem().(*Named)
   118  	}
   119  
   120  	Inst := pkg.Scope().Lookup("Inst").Type().(*Pointer).Elem().(*Named)
   121  	Node := firstFieldType(Inst)
   122  	Tree := firstFieldType(Node)
   123  	if !Identical(Inst, Tree) {
   124  		t.Fatalf("Not a cycle: got %v, want %v", Tree, Inst)
   125  	}
   126  	if Inst != Tree {
   127  		t.Errorf("Duplicate instances in cycle: %s (%p) -> %s (%p) -> %s (%p)", Inst, Inst, Node, Node, Tree, Tree)
   128  	}
   129  }
   130
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