Request: Allow merge of `forcedInclude` setting from base config when using `compile_commands.json`

[crackcomm]

Bug type: General

Describe the bug

• OS and Version: Latest Linux Mint
• VS Code Version: 1.61
• C/C++ Extension Version: v1.7.0

This bug should be pretty easy to reproduce, for example:

Create a header file suppress-warnings.h with contents:

#ifdef __INTELLISENSE__
// 20 - identifier is undefined
#pragma diag_suppress 20
#endif

Create main.cc with contents:

int main(int argc, char** argv) { fdsfsdsfd; }

Edit c_cpp_properties.json:

{
    "configurations": [
        {
            "name": "Linux",
            "includePath": ["${default}"],
            "defines": [],
            "compilerPath": "/usr/local/bin/clang++",
            "compileCommands": "${workspaceFolder}/compile_commands.json",
            "cStandard": "c17",
            "cppStandard": "gnu++20",
            "intelliSenseMode": "linux-clang-x64",
            "forcedInclude": [
                "${workspaceFolder}/suppress-warnings.h"
            ]
        }
    ],
    "version": 4
}

Example compile_commands.json (empty list won't break it):

[
  {
    "directory": "/path-to-workspace/build/src",
    "command": "true",
    "file": "/path-to-workspace/main.cc"
  }
]

Includes from forcedInclude are not included and do not suppress a warning.

If you comment compileCommands in c_cpp_properties.json - the forced include is included.

Expected behaviour:

forcedInclude is included when using compileCommands

[Colengms]

Hi @crackcomm . It's currently 'by design' that use of compile_commands.json superceeds the other settings in your c_cpp_properties.json. A compile_commands.json should include all compiler args necessary to compile the file. The C/C++ extension uses that entire command line (from either the command field, or the arguments field) to configure IntelliSense to match how the file is actually built. If a forced include is required to compile the file, it should be passed on the command line in compile_commands.json. I don't believe "true" would be a valid compiler command line. The specification for compile_commands.json is here: https://clang.llvm.org/docs/JSONCompilationDatabase.html

[crackcomm]

Hi @Colengms, indeed "true" is not a valid compiler command nevertheless it does break the behavior I was expecting. It is a valid command though.

[crackcomm]

@Colengms on the other hand - header files are never included in compile_commands.json.

[bobbrow]

@Colengms this request is in the context of #1231 trying to suppress some warnings. Does the new "merge configurations" setting apply for compile_commands.json + forcedInclude?

[Colengms]

@bobbrow The new merge feature only applies to configuration providers.

@crackcomm When a header file is opened, the extension tries to associate that header with a source file that includes it, and looks for that source file in your compile_commands.json. Note that the purpose of using compile_commands.json with the C/C++ extension is specifically so that configuration information can be inferred based on the compiler args. Without those args present, I don't believe it's accomplishing anything. You might get the behavior you expect by removing use of the compile_commands.json from your cpp_properties.json (or, adding real compile command lines, which use your forced include, to compile_commands.json).

[crackcomm]

@Colengms previously my compile_commands.json was generated by CMake, the one provided here is enough to reproduce the issue.

[Colengms]

Hi @crackcomm What you are seeing is currently by design. To add a forced include when using compile_commands.json, you would need to specify -include <file> to the command line.

It sounds like you're requesting a feature, that we merge forcedInclude settings from c_cpp_properties.json when using compile_commands.json. So, I'll change this to a feature request.