> Has anyone defined a strict subset of C to be used as target for compilers? Or ideally a more regular and simpler language, as writing a C compiler itself is fraught with pitfalls.
The main reason you'd target C is for portability and free compiler optimisations. If you start inventing new intermediate languages or C dialects, what's the benefit of transpiling in the first place? You might as well just write your own compiler backends and output the machine code directly, with optimisations around your own language's semantics rather than C.
Imho, C89 is the strict subset that a compiler ought to target, assuming they want C's portability and free compiler optimisations. It's well understood, not overly complex, and will compile to fast, sensible machine code on any architecture from the past half century.
Say I am writing a transpiler to C, and I have to choose whether I will target C89, or some arbitrary subset of C23. When would I ever choose the latter?
The only benefit I could think of is where you're also planning to write a new C compiler, and this is simplified by the C being restricted in some way. But if you're doing this, you're just writing a frontend and backend, with an awkward and unnecessary middle-end coupling to some arbitrary subset of C. What's the benefit of C being involved at all in this scenario?
And say you realise this, and opt to replace C with some kind of more abstract, C-like IR. Aren't you now just writing an LLVM clone, with all the work that entails? When the original point of targetting C was to get its portability and backends for free?
The main reason you'd target C is for portability and free compiler optimisations. If you start inventing new intermediate languages or C dialects, what's the benefit of transpiling in the first place? You might as well just write your own compiler backends and output the machine code directly, with optimisations around your own language's semantics rather than C.
Imho, C89 is the strict subset that a compiler ought to target, assuming they want C's portability and free compiler optimisations. It's well understood, not overly complex, and will compile to fast, sensible machine code on any architecture from the past half century.