cmd/vet: add defers analysis pass

Fixes #60048

Change-Id: I1553de35d5ebd9c7df9727242e888de91caca4ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/527095
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Tim King <taking@google.com>
Reviewed-by: Tim King <taking@google.com>

3 files changed, 87 insertions, 0 deletions

diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/defers.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/defers.go
new file mode 100644
index 0000000000..ed2a122f2b
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/defers.go
@@ -0,0 +1,61 @@
+// Copyright 2023 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 defers
+
+import (
+	_ "embed"
+	"go/ast"
+	"go/types"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
+	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/go/types/typeutil"
+)
+
+//go:embed doc.go
+var doc string
+
+// Analyzer is the defers analyzer.
+var Analyzer = &analysis.Analyzer{
+	Name:     "defers",
+	Requires: []*analysis.Analyzer{inspect.Analyzer},
+	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/defers",
+	Doc:      analysisutil.MustExtractDoc(doc, "defers"),
+	Run:      run,
+}
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	if !analysisutil.Imports(pass.Pkg, "time") {
+		return nil, nil
+	}
+
+	checkDeferCall := func(node ast.Node) bool {
+		switch v := node.(type) {
+		case *ast.CallExpr:
+			fn, ok := typeutil.Callee(pass.TypesInfo, v).(*types.Func)
+			if ok && fn.Name() == "Since" && fn.Pkg().Path() == "time" {
+				pass.Reportf(v.Pos(), "call to time.Since is not deferred")
+			}
+		case *ast.FuncLit:
+			return false // prune
+		}
+		return true
+	}
+
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	nodeFilter := []ast.Node{
+		(*ast.DeferStmt)(nil),
+	}
+
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		d := n.(*ast.DeferStmt)
+		ast.Inspect(d.Call, checkDeferCall)
+	})
+
+	return nil, nil
+}
diff --git a/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/doc.go b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/doc.go
new file mode 100644
index 0000000000..bdb1351628
--- /dev/null
+++ b/src/cmd/vendor/golang.org/x/tools/go/analysis/passes/defers/doc.go
@@ -0,0 +1,25 @@
+// Copyright 2023 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 defers defines an Analyzer that checks for common mistakes in defer
+// statements.
+//
+// # Analyzer defers
+//
+// defers: report common mistakes in defer statements
+//
+// The defers analyzer reports a diagnostic when a defer statement would
+// result in a non-deferred call to time.Since, as experience has shown
+// that this is nearly always a mistake.
+//
+// For example:
+//
+//	start := time.Now()
+//	...
+//	defer recordLatency(time.Since(start)) // error: call to time.Since is not deferred
+//
+// The correct code is:
+//
+//	defer func() { recordLatency(time.Since(start)) }()
+package defers
diff --git a/src/cmd/vendor/modules.txt b/src/cmd/vendor/modules.txt
index 380a05bf63..a2b1e248be 100644
--- a/src/cmd/vendor/modules.txt
+++ b/src/cmd/vendor/modules.txt
@@ -61,6 +61,7 @@ golang.org/x/tools/go/analysis/passes/cgocall
 golang.org/x/tools/go/analysis/passes/composite
 golang.org/x/tools/go/analysis/passes/copylock
 golang.org/x/tools/go/analysis/passes/ctrlflow
+golang.org/x/tools/go/analysis/passes/defers
 golang.org/x/tools/go/analysis/passes/directive
 golang.org/x/tools/go/analysis/passes/errorsas
 golang.org/x/tools/go/analysis/passes/framepointer