Support for nested invocations of proc-macro-hack expression macros.
By default, macros defined through proc-macro-hack do not support nested invocations, i.e. the code emitted by a proc-macro-hack macro invocation cannot contain recursive calls to the same proc-macro-hack macro nor calls to any other proc-macro-hack macros.
This crate provides opt-in support for such nested invocations.
To make a macro callable recursively, add a dependency on this crate from
your declaration crate and update the #[proc_macro_hack]
re-export as
follows.
// Before
# const IGNORE: &str = stringify!
// After
# const IGNORE: &str = stringify!
No change is required within your definition crate, only to the re-export in the declaration crate.
Limitations
-
Nested invocations are preprocessed by a TT-muncher, so the caller's crate will be required to contain
#![recursion_limit = "..."]
if there are lengthy macro invocations. -
Only up to 64 nested invocations are supported.