| // Copyright 2024 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package modernize providers the modernizer analyzer. |
| // |
| // # Analyzer modernize |
| // |
| // modernize: simplify code by using modern constructs |
| // |
| // This analyzer reports opportunities for simplifying and clarifying |
| // existing code by using more modern features of Go and its standard |
| // library. |
| // |
| // Each diagnostic provides a fix. Our intent is that these fixes may |
| // be safely applied en masse without changing the behavior of your |
| // program. In some cases the suggested fixes are imperfect and may |
| // lead to (for example) unused imports or unused local variables, |
| // causing build breakage. However, these problems are generally |
| // trivial to fix. We regard any modernizer whose fix changes program |
| // behavior to have a serious bug and will endeavor to fix it. |
| // |
| // To apply all modernization fixes en masse, you can use the |
| // following command: |
| // |
| // $ go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./... |
| // |
| // (Do not use "go get -tool" to add gopls as a dependency of your |
| // module; gopls commands must be built from their release branch.) |
| // |
| // If the tool warns of conflicting fixes, you may need to run it more |
| // than once until it has applied all fixes cleanly. This command is |
| // not an officially supported interface and may change in the future. |
| // |
| // Changes produced by this tool should be reviewed as usual before |
| // being merged. In some cases, a loop may be replaced by a simple |
| // function call, causing comments within the loop to be discarded. |
| // Human judgment may be required to avoid losing comments of value. |
| // |
| // Each diagnostic reported by modernize has a specific category. (The |
| // categories are listed below.) Diagnostics in some categories, such |
| // as "efaceany" (which replaces "interface{}" with "any" where it is |
| // safe to do so) are particularly numerous. It may ease the burden of |
| // code review to apply fixes in two passes, the first change |
| // consisting only of fixes of category "efaceany", the second |
| // consisting of all others. This can be achieved using the -category flag: |
| // |
| // $ modernize -category=efaceany -fix -test ./... |
| // $ modernize -category=-efaceany -fix -test ./... |
| // |
| // Categories of modernize diagnostic: |
| // |
| // - forvar: remove x := x variable declarations made unnecessary by the new semantics of loops in go1.22. |
| // |
| // - slicescontains: replace 'for i, elem := range s { if elem == needle { ...; break }' |
| // by a call to slices.Contains, added in go1.21. |
| // |
| // - minmax: replace an if/else conditional assignment by a call to |
| // the built-in min or max functions added in go1.21. |
| // |
| // - sortslice: replace sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } |
| // by a call to slices.Sort(s), added in go1.21. |
| // |
| // - efaceany: replace interface{} by the 'any' type added in go1.18. |
| // |
| // - mapsloop: replace a loop around an m[k]=v map update by a call |
| // to one of the Collect, Copy, Clone, or Insert functions from |
| // the maps package, added in go1.21. |
| // |
| // - fmtappendf: replace []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), |
| // added in go1.19. |
| // |
| // - testingcontext: replace uses of context.WithCancel in tests |
| // with t.Context, added in go1.24. |
| // |
| // - omitzero: replace omitempty by omitzero on structs, added in go1.24. |
| // |
| // - bloop: replace "for i := range b.N" or "for range b.N" in a |
| // benchmark with "for b.Loop()", and remove any preceding calls |
| // to b.StopTimer, b.StartTimer, and b.ResetTimer. |
| // |
| // B.Loop intentionally defeats compiler optimizations such as |
| // inlining so that the benchmark is not entirely optimized away. |
| // Currently, however, it may cause benchmarks to become slower |
| // in some cases due to increased allocation; see |
| // https://go.dev/issue/73137. |
| // |
| // - rangeint: replace a 3-clause "for i := 0; i < n; i++" loop by |
| // "for i := range n", added in go1.22. |
| // |
| // - stringsseq: replace Split in "for range strings.Split(...)" by go1.24's |
| // more efficient SplitSeq, or Fields with FieldSeq. |
| // |
| // - stringscutprefix: replace some uses of HasPrefix followed by TrimPrefix with CutPrefix, |
| // added to the strings package in go1.20. |
| // |
| // - waitgroup: replace old complex usages of sync.WaitGroup by less complex WaitGroup.Go method in go1.25. |
| package modernize |
