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Overview

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.

Available checks:

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. Unkeyed composite literals, flag -composites

Composite struct literals that do not use the field-keyed syntax.

Usage:

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