Disable std.cfg automatically loaded

[André Coquim]

Context:
* I'm using Cppcheck 2.13.0
* I'm trying to run cppcheck on a cross-compiled project, so I do not use the default system includes
* After reading some documentation and code in the github repository I found that "configuration for the standard libraries of C and C++, std.cfg, is always loaded by cppcheck".

Problem:
I'm trying to get rid of the missingIncludeSystem the correct way which is by specifying the paths for the files/dirs, instead of using the --supress=missingIncludeSystem. In some files where I am able to achieve this I even get new code warnings, which is a good thing, but as a result I get false syntax error in some system include files like math.h.
I understood that this is due to the load of some configurations present in file cppcheck/cfg/ std.cfg that conflict with the cross-tools header files.

As an example:

This enum exists in my cross-compilation math.h file:

enum
  {
    FP_NAN =
# define FP_NAN 0
      FP_NAN,
    FP_INFINITE =
# define FP_INFINITE 1
      FP_INFINITE,
    FP_ZERO =
# define FP_ZERO 2
      FP_ZERO,
    FP_SUBNORMAL =
# define FP_SUBNORMAL 3
      FP_SUBNORMAL,
    FP_NORMAL =
# define FP_NORMAL 4
      FP_NORMAL
  };

When I run cppcheck with preprocessor:
cppcheck math.h -E

I can see that the result becomes:

enum
{
 5 =

 0 ,
 4 =

 1 ,
 3 =

 2 ,
 2 =

 3 ,
 1 =

 4
} ;

The correct result should be:

enum
  {
    FP_NAN =

      0,
    FP_INFINITE =

     1,
    FP_ZERO =

      2,
    FP_SUBNORMAL =

     3,
    FP_NORMAL =

      4
  };

This happens because std.cfg is being loaded with this configurations:

<define name="FP_NORMAL" value="1"/>
  <define name="FP_SUBNORMAL" value="2"/>
  <define name="FP_ZERO" value="3"/>
  <define name="FP_INFINITE" value="4"/>
  <define name="FP_NAN" value="5"/>

Consequently it results in syntax error detected by cppcheck when analyzing the file or any file that includes it!

math.h:915:3: error: syntax error: 5 = [syntaxError]

What I propose here is for cppccheck not load anything automatically or to create a new cppcheck flag to not load any config file automatically, for example: --no-auto-config

Thanks

[CHR]

Not loading std.cfg is really not advisable due to the information about library functions etc. that it contains. In your case, couldn't you use a patched .cfg without the offending values?

[André Coquim]

To prove everything I said I have changed the content of std.cfg to make it "empty":

<?xml version="1.0"?>
<def format="2">
</def>

This solved the problem, but I was using a version that I downloaded personally for me.
In a corporative environment I don't have root privileges in the machine so I cannot do such a thing. Also, each time Cppcheck is upgraded the same fix is needed and this approach is not convenient since I don't have root privileges.
I understand that not loading by default may not be advisable, but that's why I proposed a new flag like --no-auto-config to be able to not load this file as an option.

Thanks

[CHR]

Using --supress=missingIncludeSystem is the way to go, making standard headers visible to cppcheck serves no purpose. That's why std.cfg exists.