Setting up the fake array is a bit more expensive than would be
expected because `rb_ary_freeze` does a lot of checks and lookup
a shape transition.
If we assume fake arrays will always be frozen, we can precompute
the flags state and just assign it.
Use plain paragraphs instead of a nested unordered list.
Remove some examples, including examples that produce warnings in
verbose mode or raise exceptions.
Explicitly document the common pitfall of using an expression as a
default value instead of using a block.
Improves activerecord by about 1% on the interpreter:
```
before: ruby 3.4.0dev (2024-07-03T18:40:10Z master f88841b8f3) [arm64-darwin23]
after: ruby 3.4.0dev (2024-07-03T18:41:14Z ruby-map 6c0df4eb32) [arm64-darwin23]
------------ ----------- ---------- ---------- ---------- ------------- ------------
bench before (ms) stddev (%) after (ms) stddev (%) after 1st itr before/after
activerecord 235.2 0.8 233.6 0.7 1.01 1.01
------------ ----------- ---------- ---------- ---------- ------------- ------------
Legend:
- after 1st itr: ratio of before/after time for the first benchmarking iteration.
- before/after: ratio of before/after time. Higher is better for after. Above 1 represents a speedup.
```
Improves YJIT by about 4%:
```
before: ruby 3.4.0dev (2024-07-03T18:40:10Z master f88841b8f3) +YJIT [arm64-darwin23]
after: ruby 3.4.0dev (2024-07-03T18:41:14Z ruby-map 6c0df4eb32) +YJIT [arm64-darwin23]
------------ ----------- ---------- ---------- ---------- ------------- ------------
bench before (ms) stddev (%) after (ms) stddev (%) after 1st itr before/after
activerecord 142.1 1.2 137.0 0.6 1.00 1.04
------------ ----------- ---------- ---------- ---------- ------------- ------------
Legend:
- after 1st itr: ratio of before/after time for the first benchmarking iteration.
- before/after: ratio of before/after time. Higher is better for after. Above 1 represents a speedup.
```
This speeds up the mail benchmark by about 7% on the interpreter:
```
before: ruby 3.4.0dev (2024-07-03T17:01:41Z master f4b313f733) [arm64-darwin23]
after: ruby 3.4.0dev (2024-07-03T17:45:50Z ruby-select de282cacd5) [arm64-darwin23]
----- ----------- ---------- ---------- ---------- ------------- ------------
bench before (ms) stddev (%) after (ms) stddev (%) after 1st itr before/after
mail 72.9 0.8 68.2 1.0 1.02 1.07
----- ----------- ---------- ---------- ---------- ------------- ------------
Legend:
- after 1st itr: ratio of before/after time for the first benchmarking iteration.
- before/after: ratio of before/after time. Higher is better for after. Above 1 represents a speedup.
```
YJIT is about 13% faster:
```
before: ruby 3.4.0dev (2024-07-03T17:01:41Z master f4b313f733) +YJIT [arm64-darwin23]
after: ruby 3.4.0dev (2024-07-03T17:45:50Z ruby-select de282cacd5) +YJIT [arm64-darwin23]
----- ----------- ---------- ---------- ---------- ------------- ------------
bench before (ms) stddev (%) after (ms) stddev (%) after 1st itr before/after
mail 51.0 0.8 45.2 0.6 1.00 1.13
----- ----------- ---------- ---------- ---------- ------------- ------------
Legend:
- after 1st itr: ratio of before/after time for the first benchmarking iteration.
- before/after: ratio of before/after time. Higher is better for after. Above 1 represents a speedup.
```
Following [Feature #20589] it can happen that we change the
capacity of a frozen array, so these assertions no longer make
sense.
Normally we don't hit them because `Array#freeze` shrinks the
array, but if somehow the Array was frozen using `Object#freeze`
then we may shrink it after it was frozen.
