62 lines
1.9 KiB
Go
62 lines
1.9 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// The errorsas package defines an Analyzer that checks that the second arugment to
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// errors.As is a pointer to a type implementing error.
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package errorsas
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import (
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"go/ast"
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"go/types"
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"golang.org/x/tools/go/analysis"
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"golang.org/x/tools/go/analysis/passes/inspect"
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"golang.org/x/tools/go/ast/inspector"
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"golang.org/x/tools/go/types/typeutil"
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)
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const doc = `report passing non-pointer or non-error values to errors.As
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The errorsas analysis reports calls to errors.As where the type
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of the second argument is not a pointer to a type implementing error.`
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var Analyzer = &analysis.Analyzer{
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Name: "errorsas",
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Doc: doc,
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Requires: []*analysis.Analyzer{inspect.Analyzer},
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Run: run,
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}
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func run(pass *analysis.Pass) (interface{}, error) {
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inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
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nodeFilter := []ast.Node{
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(*ast.CallExpr)(nil),
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}
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inspect.Preorder(nodeFilter, func(n ast.Node) {
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call := n.(*ast.CallExpr)
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fn := typeutil.StaticCallee(pass.TypesInfo, call)
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if fn == nil {
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return // not a static call
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}
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if fn.FullName() == "errors.As" && !pointerToInterfaceOrError(pass, call.Args[1]) {
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pass.Reportf(call.Pos(), "second argument to errors.As must be a pointer to an interface or a type implementing error")
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}
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})
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return nil, nil
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}
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var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)
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// pointerToInterfaceOrError reports whether the type of e is a pointer to an interface or a type implementing error.
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func pointerToInterfaceOrError(pass *analysis.Pass, e ast.Expr) bool {
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t := pass.TypesInfo.Types[e].Type
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pt, ok := t.Underlying().(*types.Pointer)
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if !ok {
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return false
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}
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_, ok = pt.Elem().Underlying().(*types.Interface)
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return ok || types.Implements(pt.Elem(), errorType)
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}
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