gopls: add and enable the slog analyzer

This analyzer is included in go/vet, and so gopls should have it as
well.

Change-Id: Ib5cbee44a1f38c4aa45d75bcaa7a345d88099d8e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/524764
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: findleyr

gopls/doc/analyzers.md

@@ -494,6 +494,24 @@ This is one of the simplifications that "gofmt -s" applies.
 
 **Enabled by default.**
 
+## **slog**
+
+check for invalid structured logging calls
+
+The slog checker looks for calls to functions from the log/slog
+package that take alternating key-value pairs. It reports calls
+where an argument in a key position is neither a string nor a
+slog.Attr, and where a final key is missing its value.
+For example,it would report
+
+	slog.Warn("message", 11, "k") // slog.Warn arg "11" should be a string or a slog.Attr
+
+and
+
+	slog.Info("message", "k1", v1, "k2") // call to slog.Info missing a final value
+
+**Enabled by default.**
+
 ## **sortslice**
 
 check the argument type of sort.Slice

gopls/internal/lsp/source/api_json.go

@@ -39,6 +39,7 @@ import (
 	"golang.org/x/tools/go/analysis/passes/printf"
 	"golang.org/x/tools/go/analysis/passes/shadow"
 	"golang.org/x/tools/go/analysis/passes/shift"
+	"golang.org/x/tools/go/analysis/passes/slog"
 	"golang.org/x/tools/go/analysis/passes/sortslice"
 	"golang.org/x/tools/go/analysis/passes/stdmethods"
 	"golang.org/x/tools/go/analysis/passes/stringintconv"
@@ -1549,6 +1550,7 @@ func defaultAnalyzers() map[string]*Analyzer {
 		nilfunc.Analyzer.Name:       {Analyzer: nilfunc.Analyzer, Enabled: true},
 		printf.Analyzer.Name:        {Analyzer: printf.Analyzer, Enabled: true},
 		shift.Analyzer.Name:         {Analyzer: shift.Analyzer, Enabled: true},
+		slog.Analyzer.Name:          {Analyzer: slog.Analyzer, Enabled: true},
 		stdmethods.Analyzer.Name:    {Analyzer: stdmethods.Analyzer, Enabled: true},
 		stringintconv.Analyzer.Name: {Analyzer: stringintconv.Analyzer, Enabled: true},
 		structtag.Analyzer.Name:     {Analyzer: structtag.Analyzer, Enabled: true},

gopls/internal/lsp/source/options.go

@@ -1,32 +1,51 @@
 Test of warning diagnostics from various analyzers:
-tests, copylocks, printf, and timeformat.
+copylocks, printf, slog, tests, and timeformat.
 
 -- go.mod --
 module example.com
 go 1.12
 
+-- flags --
+-min_go=go1.21
+
 -- bad_test.go --
 package analyzer
 
 import (
 	"fmt"
+	"log/slog"
 	"sync"
 	"testing"
 	"time"
 )
 
-func Testbad(t *testing.T) { //@diag("", re"Testbad has malformed name: first letter after 'Test' must not be lowercase")
+// copylocks
+func _() {
 	var x sync.Mutex
 	_ = x //@diag("x", re"assignment copies lock value to _: sync.Mutex")
+}
 
+// printf
+func _() {
 	printfWrapper("%s") //@diag(re`printfWrapper\(.*\)`, re"example.com.printfWrapper format %s reads arg #1, but call has 0 args")
 }
 
 func printfWrapper(format string, args ...interface{}) {
 	fmt.Printf(format, args...)
 }
 
+// slog
+func _() {
+	slog.Info("msg", 1) //@diag("1", re`slog.Info arg "1" should be a string or a slog.Attr`)
+}
+
+// tests
+func Testbad(t *testing.T) { //@diag("", re"Testbad has malformed name: first letter after 'Test' must not be lowercase")
+}
+
+// timeformat
 func _() {
 	now := time.Now()
 	fmt.Println(now.Format("2006-02-01")) //@diag("2006-02-01", re"2006-02-01 should be 2006-01-02")
 }
+