Correctly Handle relative paths in JSON Compilation Databases

[tisoft]

According to the specification, all paths specified in a JSON Compilation
database must either be absolute, or relative to the location given
in the directory field.

Fixes #1790

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This change is 

[guwirth]

@tisoft My understanding:

Think two cases should be handled:

1. directory is absolute:
   a) path is absolute ==> use path as it is
   b) path is relative==> combine directory and path
2. directory is relative:
   a) What is root in this case? directory realtive to JSON Compilation Database?
   ==> Make this somehow absolute.
   b) then same as above

What do you think?

[tisoft]

Currently it is handled this way:

if the include path is absolute, it is used as is. If it is relative it is concatenated to directory. The cwd.resolve handles both cases:

sonar-cxx/cxx-sensors/src/main/java/org/sonar/cxx/sensors/utils/JsonCompilationDatabase.java

Line 155 in ad963b3

return cwd.resolve(include).normalize().toString();

If directory is absolute, it is used as is, if directory is relative (and so the resulting concatenated path is also relative), it will be concatenated to the baseDir here:

sonar-cxx/cxx-squid/src/main/java/org/sonar/cxx/preprocessor/SourceCodeProvider.java

Line 47 in 7a07985

includeRoot = new File(baseDir, tmp);

This seems to be the correct way for me.

[guwirth]

@tisoft

baseDir is the interesting part:

• JSON Compilation Databases / "directory": "." ==> would mean location of JSON Compilation Database file?
• SQ definition of baseDir (https://docs.sonarqube.org/latest/analysis/scan/sonarscanner/)
  • ... If the files to be analyzed are not in the directory where the analysis starts from, use the sonar.projectBaseDir property to move analysis to a different directory.
  • default of sonar.projectBaseDir is "where the analysis starts from" ==> where .property file is

In case .property file and JSON Compilation Database is in the same folder this would match.

[guwirth]

@tisoft: the tests are still failing. Our CI is partly running on Linux (Travis) and partly on Windows (AppVeyor). In case you are writing tests handling absolute paths you have to split it and you need special versions for each OS.

You find some samples here: https://github.com/SonarOpenCommunity/sonar-cxx/search?l=Java&q=windows

[guwirth]

close this see #1797