5b9fea01ee
Revamp the build system to be more inline with other Prometheus exporters. Notably add Darwin and Windows build targets, and add support for releases using tar files.
68 lines
1.4 KiB
Go
68 lines
1.4 KiB
Go
// Copyright 2013 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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/*
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This file contains the code to check for useless function comparisons.
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A useless comparison is one like f == nil as opposed to f() == nil.
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*/
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package main
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import (
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"go/ast"
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"go/token"
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"go/types"
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)
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func init() {
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register("nilfunc",
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"check for comparisons between functions and nil",
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checkNilFuncComparison,
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binaryExpr)
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}
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func checkNilFuncComparison(f *File, node ast.Node) {
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e := node.(*ast.BinaryExpr)
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// Only want == or != comparisons.
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if e.Op != token.EQL && e.Op != token.NEQ {
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return
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}
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// Only want comparisons with a nil identifier on one side.
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var e2 ast.Expr
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switch {
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case f.isNil(e.X):
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e2 = e.Y
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case f.isNil(e.Y):
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e2 = e.X
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default:
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return
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}
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// Only want identifiers or selector expressions.
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var obj types.Object
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switch v := e2.(type) {
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case *ast.Ident:
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obj = f.pkg.uses[v]
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case *ast.SelectorExpr:
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obj = f.pkg.uses[v.Sel]
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default:
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return
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}
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// Only want functions.
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if _, ok := obj.(*types.Func); !ok {
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return
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}
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f.Badf(e.Pos(), "comparison of function %v %v nil is always %v", obj.Name(), e.Op, e.Op == token.NEQ)
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}
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// isNil reports whether the provided expression is the built-in nil
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// identifier.
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func (f *File) isNil(e ast.Expr) bool {
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return f.pkg.types[e].Type == types.Typ[types.UntypedNil]
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}
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