Implementing C++ Modules: Lessons Learned, Lessons Abandoned - Cameron DaCamara & Gabriel Dos Reis

--- C Modules were designed to bring more safety to your programs, while dramatically reducing compile time, resulting in overall increased productivity. How can your C toolchain meet this challenge? What can you do to take advantage of these new functionalities available in your toolbox? In this talk, we share lessons learned from implementing Modules based on the singular idea of providing robust support through the entire toolchain (from the lexer through the linker, the IDE, the build system, etc.), debunking the misconception that C Modules are just some syntactic sugar that is compiled away by the front-end. The challenges that any C compiler implementer faces include: (1) how to satisfy the requirements of merging materialization of declarations -- needed for sound handling of the global module fragments, in particular, as found in header files and header units – with associated performance cost; (2) how to take advantage of the One Defin