Specify default value for FunctionType::get's isVarArg parameter

Should we specify a default value (false) for the isVarArg parameter of the FunctionType::get functions to improve ergonomics and reduce visual noise?

Typical usage (good citizens annotate their boolean args):
… = FunctionType::get(IRB.getVoidTy(), {IntptrTy, IntptrTy}, /isVarArg=/ false);

For all usages that I could easily grep, i.e., single-line usages, true was only used 21 times. So at least mechanically, false seems to be a good default.

There are different levels for the proposed change. I also state all the cons that I could think of.

Level 0: Add default in declaration/header
Cons: No, we want to require users to specify isVarArg, i.e., force them to think about the varargs special case.
Enables simplified use in the future and gradual cleanup.

Level 1: Adapt call sites
Cons: This cleanup is not important enough to warrant the churn.

Level 2: Get rid of 2-parameter overload by specifying an additional default in the 3-parameter variant: Params = None
This requires at least a cleanup of the 2-parameter overload usages.
Cons: In addition, this would force ~16 (2-args-true and 2-args-variable) uses to specify None for the params argument (to “gain access” to the isVarArg, i.e., third positional argument).
IMO, this is not a cons. No-parameter var-args functions (no format string!) seem special enough that being explicit about the absence of normal parameters feels okay to me.

Level 3/orthogonal bonus level: Special getter for void *(void) function type
77 out of 102 usages of the 2-parameter variant are used to retrieve a void func(void) type!
Maybe this warrants a special getter, similar to Type::getInt32Ty, for 1) convenience and 2) avoiding the lookup (eagerly initialize it).
We can also have a separate discussion for this since it is orthogonal.

What do you think? Are there other cons I have overlooked?
Which level would you like to see?

Approximate counts (the regex I used are probably not 100% accurate):

Personally, I’d rather to delete the overload lacking “Params”, and otherwise leave it as is. Make all callers always specify all three arguments.

“, {}, false” is really not a lot of clutter.