github.com/amarpal/go-tools@v0.0.0-20240422043104-40142f59f616/staticcheck/sa3001/sa3001.go (about)

     1  package sa3001
     2  
     3  import (
     4  	"fmt"
     5  	"go/ast"
     6  
     7  	"github.com/amarpal/go-tools/analysis/code"
     8  	"github.com/amarpal/go-tools/analysis/lint"
     9  	"github.com/amarpal/go-tools/analysis/report"
    10  
    11  	"golang.org/x/tools/go/analysis"
    12  	"golang.org/x/tools/go/analysis/passes/inspect"
    13  )
    14  
    15  var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
    16  	Analyzer: &analysis.Analyzer{
    17  		Name:     "SA3001",
    18  		Run:      run,
    19  		Requires: []*analysis.Analyzer{inspect.Analyzer},
    20  	},
    21  	Doc: &lint.Documentation{
    22  		Title: `Assigning to \'b.N\' in benchmarks distorts the results`,
    23  		Text: `The testing package dynamically sets \'b.N\' to improve the reliability of
    24  benchmarks and uses it in computations to determine the duration of a
    25  single operation. Benchmark code must not alter \'b.N\' as this would
    26  falsify results.`,
    27  		Since:    "2017.1",
    28  		Severity: lint.SeverityError,
    29  		MergeIf:  lint.MergeIfAny,
    30  	},
    31  })
    32  
    33  var Analyzer = SCAnalyzer.Analyzer
    34  
    35  func run(pass *analysis.Pass) (interface{}, error) {
    36  	fn := func(node ast.Node) {
    37  		assign := node.(*ast.AssignStmt)
    38  		if len(assign.Lhs) != 1 || len(assign.Rhs) != 1 {
    39  			return
    40  		}
    41  		sel, ok := assign.Lhs[0].(*ast.SelectorExpr)
    42  		if !ok {
    43  			return
    44  		}
    45  		if sel.Sel.Name != "N" {
    46  			return
    47  		}
    48  		if !code.IsOfType(pass, sel.X, "*testing.B") {
    49  			return
    50  		}
    51  		report.Report(pass, assign, fmt.Sprintf("should not assign to %s", report.Render(pass, sel)))
    52  	}
    53  	code.Preorder(pass, fn, (*ast.AssignStmt)(nil))
    54  	return nil, nil
    55  }