pub const MAX_NESTING: u32 = 256;Expand description
How deep the front end will follow user-chosen structure before it refuses.
The number is chosen to be far above anything a person writes and far below anything the stack
notices. SICP’s deepest expression is under 20 levels and the corpus’s is 11; the parser spends
about 18 KiB per level in an unoptimised build, which the_ceiling_fits_the_declared_stack
measures rather than assumes, so this ceiling costs under 5 MiB — inside the 8 MiB a main
thread ordinarily has, and a small fraction of the STACK_BYTES declared below. A ceiling
nobody legitimately reaches is the point: this bound exists to turn an abort into a message,
not to have an opinion about style.