defers.go

     1  // Copyright 2023 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 defers
     6  
     7  import (
     8  	_ "embed"
     9  	"go/ast"
    10  
    11  	"golang.org/x/tools/go/analysis"
    12  	"golang.org/x/tools/go/analysis/passes/inspect"
    13  	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
    14  	"golang.org/x/tools/go/ast/inspector"
    15  	"golang.org/x/tools/go/types/typeutil"
    16  	"golang.org/x/tools/internal/analysisinternal"
    17  )
    18  
    19  //go:embed doc.go
    20  var doc string
    21  
    22  // Analyzer is the defers analyzer.
    23  var Analyzer = &analysis.Analyzer{
    24  	Name:     "defers",
    25  	Requires: []*analysis.Analyzer{inspect.Analyzer},
    26  	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/defers",
    27  	Doc:      analysisutil.MustExtractDoc(doc, "defers"),
    28  	Run:      run,
    29  }
    30  
    31  func run(pass *analysis.Pass) (any, error) {
    32  	if !analysisinternal.Imports(pass.Pkg, "time") {
    33  		return nil, nil
    34  	}
    35  
    36  	checkDeferCall := func(node ast.Node) bool {
    37  		switch v := node.(type) {
    38  		case *ast.CallExpr:
    39  			if analysisinternal.IsFunctionNamed(typeutil.Callee(pass.TypesInfo, v), "time", "Since") {
    40  				pass.Reportf(v.Pos(), "call to time.Since is not deferred")
    41  			}
    42  		case *ast.FuncLit:
    43  			return false // prune
    44  		}
    45  		return true
    46  	}
    47  
    48  	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
    49  
    50  	nodeFilter := []ast.Node{
    51  		(*ast.DeferStmt)(nil),
    52  	}
    53  
    54  	inspect.Preorder(nodeFilter, func(n ast.Node) {
    55  		d := n.(*ast.DeferStmt)
    56  		ast.Inspect(d.Call, checkDeferCall)
    57  	})
    58  
    59  	return nil, nil
    60  }
    61
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