From 5d554db541e60a986ced2856bb5f57efa142065d Mon Sep 17 00:00:00 2001
From: Denis Limarev <denislimarev@gmail.com>
Date: Tue, 4 Jan 2022 00:57:05 +0300
Subject: [PATCH] gocritic: support autofix (#2450)

---
 Makefile                          |  6 ++++++
 pkg/golinters/gocritic.go         | 19 ++++++++++++++++---
 test/ruleguard/rangeExprCopy.go   | 14 ++++++++++++++
 test/testdata/fix/in/gocritic.go  | 22 ++++++++++++++++++++++
 test/testdata/fix/out/gocritic.go | 22 ++++++++++++++++++++++
 5 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 test/ruleguard/rangeExprCopy.go
 create mode 100644 test/testdata/fix/in/gocritic.go
 create mode 100644 test/testdata/fix/out/gocritic.go

diff --git a/Makefile b/Makefile
index 1f94ecb691be..1ba54cb23ebe 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,12 @@ test: build
 	GL_TEST_RUN=1 go test -v -parallel 2 ./...
 .PHONY: test
 
+# ex: T=gofmt.go make test_fix
+# the value of `T` is the name of a file from `test/testdata/fix`
+test_fix: build
+	GL_TEST_RUN=1 go test -v ./test -count 1 -run TestFix/$T
+.PHONY: test_fix
+
 test_race: build_race
 	GL_TEST_RUN=1 ./golangci-lint run -v --timeout=5m
 .PHONY: test_race
diff --git a/pkg/golinters/gocritic.go b/pkg/golinters/gocritic.go
index d292aacd71ae..ea3a3cbcbe8b 100644
--- a/pkg/golinters/gocritic.go
+++ b/pkg/golinters/gocritic.go
@@ -48,8 +48,9 @@ Dynamic rules are written declaratively with AST patterns, filters, report messa
 			}
 
 			linterCtx.SetPackageInfo(pass.TypesInfo, pass.Pkg)
-			var res []goanalysis.Issue
 			pkgIssues := runGocriticOnPackage(linterCtx, enabledCheckers, pass.Files)
+			res := make([]goanalysis.Issue, 0, len(pkgIssues))
+
 			for i := range pkgIssues {
 				res = append(res, goanalysis.NewIssue(&pkgIssues[i], pass))
 			}
@@ -179,11 +180,23 @@ func runGocriticOnFile(ctx *gocriticlinter.Context, f *ast.File, checkers []*goc
 		// as read-only structure, so no copying is required.
 		for _, warn := range c.Check(f) {
 			pos := ctx.FileSet.Position(warn.Node.Pos())
-			res = append(res, result.Issue{
+			issue := result.Issue{
 				Pos:        pos,
 				Text:       fmt.Sprintf("%s: %s", c.Info.Name, warn.Text),
 				FromLinter: gocriticName,
-			})
+			}
+
+			if warn.HasQuickFix() {
+				issue.Replacement = &result.Replacement{
+					Inline: &result.InlineFix{
+						StartCol:  pos.Column - 1,
+						Length:    int(warn.Node.End() - warn.Node.Pos()),
+						NewString: string(warn.Suggestion.Replacement),
+					},
+				}
+			}
+
+			res = append(res, issue)
 		}
 	}
 
diff --git a/test/ruleguard/rangeExprCopy.go b/test/ruleguard/rangeExprCopy.go
new file mode 100644
index 000000000000..d68b45e61158
--- /dev/null
+++ b/test/ruleguard/rangeExprCopy.go
@@ -0,0 +1,14 @@
+// go:build ruleguard
+package ruleguard
+
+import (
+	"github.com/quasilyte/go-ruleguard/dsl"
+)
+
+func RangeExprVal(m dsl.Matcher) {
+	m.Match(`for _, $_ := range $x { $*_ }`, `for _, $_ = range $x { $*_ }`).
+		Where(m["x"].Addressable && m["x"].Type.Size >= 512).
+		Report(`$x copy can be avoided with &$x`).
+		At(m["x"]).
+		Suggest(`&$x`)
+}
diff --git a/test/testdata/fix/in/gocritic.go b/test/testdata/fix/in/gocritic.go
new file mode 100644
index 000000000000..4191eea1319a
--- /dev/null
+++ b/test/testdata/fix/in/gocritic.go
@@ -0,0 +1,22 @@
+//args: -Egocritic
+//config: linters-settings.gocritic.enabled-checks=ruleguard
+//config: linters-settings.gocritic.settings.ruleguard.rules=ruleguard/rangeExprCopy.go,ruleguard/strings_simplify.go
+package p
+
+import (
+	"strings"
+)
+
+func gocritic() {
+	var xs [2048]byte
+
+	// xs -> &xs
+	for _, x := range xs {
+		print(x)
+	}
+
+	// strings.Count("foo", "bar") == 0 -> !strings.Contains("foo", "bar")
+	if strings.Count("foo", "bar") == 0 {
+		print("qu")
+	}
+}
diff --git a/test/testdata/fix/out/gocritic.go b/test/testdata/fix/out/gocritic.go
new file mode 100644
index 000000000000..2c66ef21b9f5
--- /dev/null
+++ b/test/testdata/fix/out/gocritic.go
@@ -0,0 +1,22 @@
+//args: -Egocritic
+//config: linters-settings.gocritic.enabled-checks=ruleguard
+//config: linters-settings.gocritic.settings.ruleguard.rules=ruleguard/rangeExprCopy.go,ruleguard/strings_simplify.go
+package p
+
+import (
+	"strings"
+)
+
+func gocritic() {
+	var xs [2048]byte
+
+	// xs -> &xs
+	for _, x := range &xs {
+		print(x)
+	}
+
+	// strings.Count("foo", "bar") == 0 -> !strings.Contains("foo", "bar")
+	if !strings.Contains("foo", "bar") {
+		print("qu")
+	}
+}