streamline a[begin] lowering via firstindex(a, n)

NEWS.md

@@ -44,6 +44,9 @@ Language changes
   a function like other operators. The dotted version `.-->` is now parsed as well.
   For backwards compatibility, `-->` still parses using its own expression head
   instead of `:call`.
+* Instances of `UniformScaling` are no longer `isequal` to matrices. Previous
+  behaviour violated the rule that `isequal(x, y)` implies `hash(x) == hash(y)`.
+* The `a[begin]` syntax now calls `firstindex(a,1)` rather than `first(axes(a,1))` ([#35779]).
 * `⌿` (U+233F) and `¦` (U+00A6) are now infix operators with times-like and plus-like precedence,
   respectively. Previously they were parsed as identifier characters ([#37973]).
 

src/julia-syntax.scm

@@ -105,7 +105,7 @@
   (if (null? tuples)
       (if (and last (= n 1))
           `(call (top firstindex) ,a)
-          `(call (top first) (call (top axes) ,a ,n)))
+          `(call (top firstindex) ,a ,n))
       (let ((dimno `(call (top +) ,(- n (length tuples))
                           ,.(map (lambda (t) `(call (top length) ,t))
                                  tuples))))