False positives in SonarLint C++ rules in C header files in Eclipse

willemr · January 19, 2021, 2:39pm

I am having a lot of false positives when using SonarLint on my local Eclipse based IDE. It looks like this only happens in header (.h) files.

For instance the following C++ rule is detected as a critical code smell: ‘#Macros should not be used to define constants’

This false positive is shown on each define. So for instance on:

#define ADDRESS_END      0xF0041FFFU

But also C++ rules like ‘Non-const global variables should not be used (cpp:S5421)’ on a prototype of a C function and ‘C-style array should not be used (cpp:S5945)’ on an array definition in a function prototype.

This is strange since this project is a pure C code project and this rule is not enabled for this project on the SonarQube server. SonarLint is bind to this SonarQube project and this issue is not shown in SonarQube itself. It is also not possible to disable this rule locally but this is as expected since the rules are obtained from SonarQube.

We are using the latest build_wrapper to analyze our code.

First we were running SonarQube 8.4 and after updating to 8.6 this issue is still there. On 8.4 we had the SonarCFamily installed but with the current installation we don’t.

JBL_SonarSource · January 22, 2021, 5:59pm

Hello @willemr, thank you for your report!

First, as far as I can tell, SonarQube 8.6 comes with the CFamily analyzer pre-installed, in version 6.15.0.25047 - you don’t have to install it manually.

Which “Project Natures” does your project have? (Right click on the project Properties Project Natures).

I tried to reproduce on the latest Eclipse + SonarQube 8.6 DE and I observe a behavior similar to what you report when the project has the “C++” nature - which I would expect. If the project has the “C” nature instead, the rules specific to C++ are not triggered.

See the difference in the screenshots below, first one was created as a “C” project, does not trigger the C++ rules:

Second one was created as a “C++” project, does trigger the rules:

willemr · January 25, 2021, 10:02am

None. In Code Composer Studio this is not a property of the project properties. What I did find are the Language Mappings as bellow:

Here also C++ header and source files are configured. But also after removing those two the issues are still in (also after reboot and re-analyzing all files).

The last thing I tried are the preferences and this does include the Project Natures properties but not the options as your Eclipse screenshots show.

JBL_SonarSource · January 25, 2021, 3:46pm

Thank you for the additional details.

I downloaded the latest CCS from the TI website and created a MSP430 project, and indeed a simple .h file is analyzed as a C++ header file by SonarLint, even though it is considered as a C header file type in the project explorer.

I tried to debug the code where SonarLint detects the file type, and it seems that the underlying CDT infrastructure is classifying it as org.eclipse.cdt.core.cxxHeader, which is the value associated to C++ header files.

However, using the project’s “Advanced settings”, I was able to override this behavior and force .h files to be viewed as "C Header File"s - see screenshot below:

And with this setup, the C++ rules aren’t applied to header files anymore.

willemr · January 25, 2021, 4:36pm

This also works on my project with an older version of CCS. Thanks!

I will now check if it doesn’t break any other functionality. But it sure does solve the SonarLint C++ false positives!

system · February 1, 2021, 4:36pm

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