src

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git clone git://code.dwrz.net/src
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sa4017.go (2388B)

      1 package sa4017
      2 
      3 import (
      4 	"fmt"
      5 	"go/types"
      6 
      7 	"honnef.co/go/tools/analysis/code"
      8 	"honnef.co/go/tools/analysis/facts/purity"
      9 	"honnef.co/go/tools/analysis/lint"
     10 	"honnef.co/go/tools/analysis/report"
     11 	"honnef.co/go/tools/go/ir"
     12 	"honnef.co/go/tools/go/types/typeutil"
     13 	"honnef.co/go/tools/internal/passes/buildir"
     14 
     15 	"golang.org/x/tools/go/analysis"
     16 )
     17 
     18 var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
     19 	Analyzer: &analysis.Analyzer{
     20 		Name:     "SA4017",
     21 		Run:      run,
     22 		Requires: []*analysis.Analyzer{buildir.Analyzer, purity.Analyzer},
     23 	},
     24 	Doc: &lint.RawDocumentation{
     25 		Title:    `Discarding the return values of a function without side effects, making the call pointless`,
     26 		Since:    "2017.1",
     27 		Severity: lint.SeverityWarning,
     28 		MergeIf:  lint.MergeIfAll,
     29 	},
     30 })
     31 
     32 var Analyzer = SCAnalyzer.Analyzer
     33 
     34 func run(pass *analysis.Pass) (any, error) {
     35 	pure := pass.ResultOf[purity.Analyzer].(purity.Result)
     36 
     37 fnLoop:
     38 	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
     39 		if code.IsInTest(pass, fn) {
     40 			params := fn.Signature.Params()
     41 			for param := range params.Variables() {
     42 				if typeutil.IsPointerToTypeWithName(param.Type(), "testing.B") {
     43 					// Ignore discarded pure functions in code related
     44 					// to benchmarks. Instead of matching BenchmarkFoo
     45 					// functions, we match any function accepting a
     46 					// *testing.B. Benchmarks sometimes call generic
     47 					// functions for doing the actual work, and
     48 					// checking for the parameter is a lot easier and
     49 					// faster than analyzing call trees.
     50 					continue fnLoop
     51 				}
     52 			}
     53 		}
     54 
     55 		for _, b := range fn.Blocks {
     56 			for _, ins := range b.Instrs {
     57 				ins, ok := ins.(*ir.Call)
     58 				if !ok {
     59 					continue
     60 				}
     61 				refs := ins.Referrers()
     62 				if refs == nil || len(*refs) > 0 {
     63 					continue
     64 				}
     65 
     66 				callee := ins.Common().StaticCallee()
     67 				if callee == nil {
     68 					continue
     69 				}
     70 				if callee.Object() == nil {
     71 					// TODO(dh): support anonymous functions
     72 					continue
     73 				}
     74 				if _, ok := pure[callee.Object().(*types.Func)]; ok {
     75 					if pass.Pkg.Path() == "fmt_test" && callee.Object().(*types.Func).FullName() == "fmt.Sprintf" {
     76 						// special case for benchmarks in the fmt package
     77 						continue
     78 					}
     79 					report.Report(pass, ins, fmt.Sprintf("%s doesn't have side effects and its return value is ignored", callee.Object().Name()))
     80 				}
     81 			}
     82 		}
     83 	}
     84 	return nil, nil
     85 }