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manual.docbook: added documentation about <not-bool> and <pure>

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Daniel Marjamäki 2016-07-29 23:09:01 +02:00
parent 45a3bf6f6f
commit 4e338e952d
1 changed files with 89 additions and 2 deletions
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man/manual.docbook
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@ -690,6 +690,11 @@ Checking test.c...
<literal>--enable=information</literal> to get hints about what you
should configure.</para>
<para>It is recommended that you use the <literal>Library
Editor</literal> in the <literal>Cppcheck GUI</literal> to edit
configuration files. It is available in the <literal>View</literal>
menu. All settings are not documented in this manual.</para>
<para>The command line cppcheck will try to load custom .cfg files from
the working path - execute cppcheck from the path where the .cfg files
are.</para>
@ -805,7 +810,9 @@ Checking pen1.c...
attribute and their number of arguments. The name is a comma-separated
list of function names. For functions in namespaces or classes, just
provide their fully qualified name. For example: <literal>&lt;function
name="memcpy,std::memcpy"&gt;</literal>.</para>
name="memcpy,std::memcpy"&gt;</literal>. If you have template functions
then provide their instantiated names <literal>&lt;function
name="dostuff&lt;int&gt;"&gt;</literal>.</para>
<section>
<title>Function arguments</title>
@ -820,6 +827,43 @@ Checking pen1.c...
that function. The specifications for individual arguments override
this setting.</para>
<section>
<title>Not bool</title>
<para>Here is an example program with misplaced comparison:</para>
<programlisting>void test()
{
if (MemCmp(buffer1, buffer2, 1024==0)) {}
}</programlisting>
<para><literal>Cppcheck</literal> assumes that it is fine to pass
boolean values to functions:</para>
<programlisting># cppcheck notbool.c
Checking notbool.c...</programlisting>
<para>If you provide a configuration file then Cppcheck detects the
bug:</para>
<programlisting># cppcheck --library=notbool.cfg notbool.c
Checking notbool.c...
[notbool.c:5]: (error) Invalid MemCmp() argument nr 3. A non-boolean value is required.</programlisting>
<para>Here is the minimal notbool.cfg</para>
<para><programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
&lt;function name="MemCmp"&gt;
&lt;arg nr="1"/&gt;
&lt;arg nr="2"/&gt;
&lt;arg nr="3"&gt;
&lt;not-bool/&gt;
&lt;/arg&gt;
&lt;/function&gt;
&lt;/def&gt;</programlisting></para>
</section>
<section>
<title>Uninitialized memory</title>
@ -1120,6 +1164,8 @@ Checking noreturn.c...
&lt;def&gt;
&lt;function name="ZeroMemory"&gt;
&lt;noreturn&gt;false&lt;/noreturn&gt;
&lt;arg nr="1"/&gt;
&lt;arg nr="2"/&gt;
&lt;/function&gt;
&lt;/def&gt;</programlisting>
</section>
@ -1148,7 +1194,7 @@ Checking useretval.c...</programlisting>
<programlisting># cppcheck --library=lib.cfg --enable=warning useretval.c
Checking useretval.c...
[noreturn.c:3]: (warning) Return value of function strcmp() is not used.</programlisting>
[useretval.c:3]: (warning) Return value of function strcmp() is not used.</programlisting>
<para>Here is a minimal <literal>lib.cfg</literal> file:</para>
@ -1156,6 +1202,47 @@ Checking useretval.c...
&lt;def&gt;
&lt;function name="strcmp"&gt;
&lt;use-retval/&gt;
&lt;arg nr="1"/&gt;
&lt;arg nr="2"/&gt;
&lt;/function&gt;
&lt;/def&gt;</programlisting>
</section>
<section>
<title>pure</title>
<para>A function that is pure will calculate a return value and has no
side effects. If the same parameters are given twice then the same
return value will be calculated twice.</para>
<programlisting>void f(int x)
{
if (calculate(x) == 213) {
} else if (calculate(x) == 213) {
// unreachable code
}
}</programlisting>
<para>Cppcheck reports no warning</para>
<programlisting># cppcheck pure.c
Checking pure.c...</programlisting>
<para>If a proper <literal>lib.cfg</literal> is provided, the
unreachable code is detected:</para>
<programlisting># cppcheck --enable=style --library=pure pure.c
Checking pure.c...
[pure.c:7]: (style) Expression is always false because 'else if' condition matches previous condition at line 5.</programlisting>
<para>Here is a minimal <literal>pure.cfg</literal> file:</para>
<programlisting>&lt;?xml version="1.0"?&gt;
&lt;def&gt;
&lt;function name="calculate"&gt;
&lt;pure/&gt;
&lt;arg nr="1"/&gt;
&lt;/function&gt;
&lt;/def&gt;</programlisting>
</section>