erl_lint

MODULE

erl_lint

MODULE SUMMARY

The Erlang Code Linter

DESCRIPTION

This module is used to check Erlang code for illegal syntax and other bugs. It also warns against coding practices which are not recommended.

The errors detected include:

• redefined and undefined functions


• unbound and unsafe variables


• illegal record usage.



Warnings include:

• unused functions and imports


• variables imported into matches


• variables exported from if/case/receive


• variables shadowed in lambdas and list comprehensions.



Some of the warnings are optional, and can be turned on by giving the appropriate option, described below.

The functions in this module are invoked automatically by the Erlang compiler and there is no reason to invoke these functions separately unless you have written your own Erlang compiler.

EXPORTS

module(AbsForms) -> {ok,Warnings} | {error,Errors,Warnings}
module(AbsForms, FileName) -> {ok,Warnings} | {error,Errors,Warnings}
module(AbsForms, FileName, CompileOptions) -> {ok,Warnings} | {error,Errors,Warnings}

Types:
AbsForms = [term()]
FileName = FileName2 = atom() | string()
Warnings = Errors = [{Filename2,[ErrorInfo]}]
ErrorInfo = see separate description below.
CompileOptions = [term()]

This function checks all the forms in a module for errors. It returns:

{ok,Warnings}

There were no errors in the module.


{error,Errors,Warnings}

There were errors in the module.


The elements of Options selecting optional warnings are as follows:

{format, Verbosity}

Causes warnings to be emitted for malformed format strings as arguments to io:format and similar functions. Verbosity selects the amount of warnings: 0 = no warnings; 1 = warnings for invalid format strings; 2 = warnings also when the validity could not be checked (for example, when the format string argument is a variable).


unused_vars

Causes warnings to be emitted for variables which are not used, with the exception of variables beginning with an underscore ("Prolog style warnings").


The AbsForms of a module which comes from a file that is read through epp, the Erlang pre-processor, can come from many files. This means that any references to errors must include the file name (see epp, or parser erl_parse The warnings and errors returned have the following format:

    [{FileName2,[ErrorInfo]}]

The errors and warnings are listed in the order in which they are encountered in the forms. This means that the errors from one file may be split into different entries in the list of errors.

is_guard_test(Expr) -> bool()

Types:
Expr = term()

This function tests if Expr is a legal guard test. Expr is an Erlang term representing the abstract form for the expression. erl_parse:parse_exprs(Tokens) can be used to generate a list of Expr.

format_error(ErrorDescriptor) -> string()

Types:
ErrorDescriptor = errordesc()

Takes an ErrorDescriptor and returns a string which describes the error or warning. This function is usually called implicitly when processing an ErrorInfo structure (see below).

Error Information

The ErrorInfo mentioned above is the standard ErrorInfo structure which is returned from all IO modules. It has the following format:

    {ErrorLine, Module, ErrorDescriptor}

A string which describes the error is obtained with the following call:

apply(Module, format_error, ErrorDescriptor)

See Also

erl_parse, epp

AUTHORS

Robert Virding - support@erlang.ericsson.se