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When using clang LTO in the case that cpp files are compiled clang will proudce LLVM bitcode files. This doesn't work correctly with the alt-entry point feature yet, the meta json file isn't produced in all cases

Reproduction:

• compile a compilation unit with 3 alternative entry points
• three binaries will appear
• remove 2 alternative entry points and compile again
• the 2 binaries from the previous compilation still exist

We could simply search for files with the correct naming scheme and remove these

The EntryAttr should be allowed to exist on static method declarations and function declarations with the signature int (int argc, char *argv[]), making that method an additional entry point to the program. The frontend should decide whether to honor the EntryAttr declarations based on a compiler flag -fmultiple-entry-points, if that flag is not set the __attribute((entry)) declarations should be ignored.

Details:

• declarations marked with __attribute((entry)) will have the same constraints as a normal main function, thus they are not allowed to be recursive
• declarations annotated with __attribute((entry)) need to have the signature int (int, char **) even when -fmultiple-entry-points is not set, the flag only controls the code generation behavior.
• templated entry declarations are replaced eagerly, thus a templated instantiation of a surrounding class causes the entry declaration itself to be emitted.

Implementation details:

• Can be handled similarly to the existing UsedAttr
• We have to emit some metadata which can be used by the linker to emit separate binaries

The code generation modification for implementing the meta attribute could use some cleanup

The data a lambda captures has to be serialized so that it can be executed in a serverless function. The compiler should provide a generic interface which can be used to synthesize serialization and deserialization functions at compile-time in user-space.

Open questions?

• How should generic lambdas be handled - does it just work?