compiler: Implement @disableIntrinsics() builtin function.

[alexrp]

This implements #22110, and in a way that also satisfies the use case for #21833. If accepted, this would therefore supersede #21900.

I won't add any usage of this builtin to compiler-rt and std yet as this will require a zig1.wasm update.

Closes #21833.
Closes #22110.

[wooster0]

Might be nice to add docs for this in the langref as well, along with disableInstrumentation maybe? (#21424)

I won't add any usage of this builtin to compiler-rt and std yet

Or I guess it can be done then

[alexrp]

Will write docs if/when it's approved.

[andrewrk]

Looks good other than this strange snippet I see here

[alexrp]

@andrewrk do you have any thoughts on nuking -fno-builtin (a rather blunt instrument) in favor of requiring explicit usage of @disableIntrinsics() where necessary? (Would be follow-up work since it needs a zig1.wasm update.)

[andrewrk]

Yeah I'm in favor

[andrewrk]

alexrp enabled auto-merge 2 minutes ago

you have the patience of a saint

[alexrp]

👼