buildtag.go

Documentation: cmd/fix

     1  // Copyright 2020 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 main
     6  
     7  import (
     8  	"go/ast"
     9  	"go/version"
    10  	"strings"
    11  )
    12  
    13  func init() {
    14  	register(buildtagFix)
    15  }
    16  
    17  const buildtagGoVersionCutoff = "go1.18"
    18  
    19  var buildtagFix = fix{
    20  	name: "buildtag",
    21  	date: "2021-08-25",
    22  	f:    buildtag,
    23  	desc: `Remove +build comments from modules using Go 1.18 or later`,
    24  }
    25  
    26  func buildtag(f *ast.File) bool {
    27  	if version.Compare(*goVersion, buildtagGoVersionCutoff) < 0 {
    28  		return false
    29  	}
    30  
    31  	// File is already gofmt-ed, so we know that if there are +build lines,
    32  	// they are in a comment group that starts with a //go:build line followed
    33  	// by a blank line. While we cannot delete comments from an AST and
    34  	// expect consistent output in general, this specific case - deleting only
    35  	// some lines from a comment block - does format correctly.
    36  	fixed := false
    37  	for _, g := range f.Comments {
    38  		sawGoBuild := false
    39  		for i, c := range g.List {
    40  			if strings.HasPrefix(c.Text, "//go:build ") {
    41  				sawGoBuild = true
    42  			}
    43  			if sawGoBuild && strings.HasPrefix(c.Text, "// +build ") {
    44  				g.List = g.List[:i]
    45  				fixed = true
    46  				break
    47  			}
    48  		}
    49  	}
    50  
    51  	return fixed
    52  }
    53
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