Add support for C/C++ #embed

[rascalDan]

Make sure you completed the following tasks

• I searched the discussions
• I searched the closed and open issues

Environment and version details

• Operating System+version: Gentoo Linux 2.18
• Compiler+version: GCC 15+, Clang 21+ (maybe earlier)
• Shell: Bash
• B2 Version: B2 5.4.2 (OS=LINUX, jobs=8)

Describe your use case

Embedding external assets into C/C++ executables. Currently using it to embed SQL, but other possibilities exist aplenty. (OpenGL shader source, etc)

Describe the solution you'd like

Update src/tools/types/cpp.jam to support #embed as well as #include. I've played locally, and given my understanding of #embed itself and b2's dependency tracking, I think it's as simple as changing the pattern rule to:

    rule pattern ( )
    {
        return "^[ \t]*#[ \t]*include[ \t]*(<[^<]+>|\"[^\"]+\")" , 
                "^[ \t]*#[ \t]*embed[ \t]*(<[^<]+>|\"[^\"]+\")" ; 
    }

Alternatives, if applicable

Given I only have #embed used in a single file right now, manually re-saving that file "works" but its a faff... the above rule change works for me.

[grisumbras]

Is the semantics of include directories the same for #embed and #include? Or do they have a separate set of embed directories?

[rascalDan]

Damn. That never occurred to me because I'd only used it for local resources... but unfortunately, they are separate and I appreciate that complicates the matter somewhat. GCC and Clang both use --embed-dir= and maintain a separate list of directories.