Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string. Vet uses heuristics that do not guarantee all reports are genuine problems, but it can find errors not caught by the compilers.
Its exit code is 2 for erroneous invocation of the tool, 1 if a problem was reported, and 0 otherwise. Note that the tool does not check every possible problem and depends on unreliable heuristics so it should be used as guidance only, not as a firm indicator of program correctness.
By default all checks are performed, but if explicit flags are provided, only those identified by the flags are performed.
1. Printf family, flag -printf
Suspicious calls to functions in the Printf family, including any functions with these names:
Print Printf Println Fprint Fprintf Fprintln Sprint Sprintf Sprintln Error Errorf Fatal Fatalf Panic Panicf Panicln
If the function name ends with an 'f', the function is assumed to take a format descriptor string in the manner of fmt.Printf. If not, vet complains about arguments that look like format descriptor strings.
It also checks for errors such as using a Writer as the first argument of Printf.
2. Methods, flag -methods
Non-standard signatures for methods with familiar names, including:
Format GobEncode GobDecode MarshalJSON MarshalXML Peek ReadByte ReadFrom ReadRune Scan Seek UnmarshalJSON UnreadByte UnreadRune WriteByte WriteTo
3. Struct tags, flag -structtags
Struct tags that do not follow the format understood by reflect.StructTag.Get.
4. Untagged composite literals, flag -composites
Composite struct literals that do not use the type-tagged syntax.
go tool vet [flag] [file.go ...] go tool vet [flag] [directory ...] # Scan all .go files under directory, recursively
The other flags are:
-v Verbose mode -printfuncs A comma-separated list of print-like functions to supplement the standard list. Each entry is in the form Name:N where N is the zero-based argument position of the first argument involved in the print: either the format or the first print argument for non-formatted prints. For example, if you have Warn and Warnf functions that take an io.Writer as their first argument, like Fprintf, -printfuncs=Warn:1,Warnf:1
Vet is a simple checker for static errors in Go source code. See doc.go for more information.