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<H1>erl_lint</H1>
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<H3>MODULE</H3>
<DIV CLASS=REFBODY>
erl_lint
</DIV>

<H3>MODULE SUMMARY</H3>
<DIV CLASS=REFBODY>
The Erlang Code Linter
</DIV>

<H3>DESCRIPTION</H3>
<DIV CLASS=REFBODY>

<P>This module is used to check Erlang code for illegal syntax and
other bugs. It also warns against coding practices which are not recommended. 
<P>The errors detected include:
<P>
<UL>

<LI>
redefined and undefined functions
</LI>


<LI>
unbound and unsafe variables
</LI>


<LI>
illegal record usage.
</LI>


</UL>

<P>Warnings include:
<P>
<UL>

<LI>
unused functions and imports
</LI>


<LI>
variables imported into matches
</LI>


<LI>
variables exported from <CODE>if</CODE>/<CODE>case</CODE>/<CODE>receive</CODE>
</LI>


<LI>
variables shadowed in lambdas and list comprehensions.
</LI>


</UL>

<P>Some of the warnings are optional, and can be turned on by giving the
appropriate option, described below.
<P>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.
</DIV>

<H3>EXPORTS</H3>

<P><A NAME="module/1"><STRONG><CODE>module(AbsForms) -&#62; {ok,Warnings} | {error,Errors,Warnings}</CODE></STRONG></A><BR>
<A NAME="module/2"><STRONG><CODE>module(AbsForms, FileName) -&#62; {ok,Warnings} | {error,Errors,Warnings}</CODE></STRONG></A><BR>
<A NAME="module/3"><STRONG><CODE>module(AbsForms, FileName, CompileOptions) -&#62; {ok,Warnings} | {error,Errors,Warnings}</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>AbsForms = [term()]</CODE></STRONG><BR>
<STRONG><CODE>FileName = FileName2 = atom() | string()</CODE></STRONG><BR>
<STRONG><CODE>Warnings = Errors = [{Filename2,[ErrorInfo]}]</CODE></STRONG><BR>
<STRONG><CODE>ErrorInfo = see separate description below.</CODE></STRONG><BR>
<STRONG><CODE>CompileOptions = [term()]</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

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

<P>
<DL>

<DT>
<CODE>{ok,Warnings}</CODE>
</DT>

<DD>
There were no errors in the module.<BR>

</DD>

<DT>
<CODE>{error,Errors,Warnings}</CODE>
</DT>

<DD>
There were errors in the module.<BR>

</DD>

</DL>

<P>Since this module is of interest only to the maintainers of
        the compiler, and to avoid having the same description in two
        places to avoid the usual maintainence nightmare, the elements
        of <CODE>Options</CODE> that control the warnings are only described
        in the manual page for the <CODE>compile</CODE> module.


<P>The <CODE>AbsForms</CODE> of a module which comes from a file that is read through <CODE>epp</CODE>, the
Erlang pre-processor, can come from many
files. This means that any references to errors must include
the file name (see <A HREF="epp.html">epp(3)</A>, 
or parser <A HREF="erl_parse.html">erl_parse(3)</A>
        The warnings and errors returned have the
following format:


<PRE>
    [{FileName2,[ErrorInfo]}]
</PRE>

<P>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.

</DIV>

<P><A NAME="is_guard_test/1"><STRONG><CODE>is_guard_test(Expr) -&#62; bool()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Expr = term()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

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

</DIV>

<P><A NAME="format_error/1"><STRONG><CODE>format_error(ErrorDescriptor) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>ErrorDescriptor = errordesc()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

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

</DIV>

<H3>Error Information</H3>
<DIV CLASS=REFBODY>

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


<PRE>
    {ErrorLine, Module, ErrorDescriptor}
</PRE>

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


<PRE>
apply(Module, format_error, ErrorDescriptor)
</PRE>

</DIV>

<H3>See Also</H3>
<DIV CLASS=REFBODY>

<P><A HREF="erl_parse.html">erl_parse(3)</A>,
<A HREF="epp.html">epp(3)</A>

</DIV>

<H3>AUTHORS</H3>
<DIV CLASS=REFBODY>
Robert Virding - support@erlang.ericsson.se<BR>

</DIV>
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<SMALL>stdlib 1.13.2<BR>
Copyright &copy; 1991-2004
<A HREF="http://www.erlang.se">Ericsson AB</A><BR>
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