fix #17338, broken showing of SimpleVector (#17339)

Author: JeffBezanson

base/essentials.jl

@@ -173,6 +173,7 @@ done(v::SimpleVector,i) = (i > v.length)
 isempty(v::SimpleVector) = (v.length == 0)
 indices(v::SimpleVector) = (OneTo(length(v)),)
 linearindices(v::SimpleVector) = indices(v, 1)
+indices(v::SimpleVector, d) = d <= 1 ? indices(v)[d] : OneTo(1)
 
 function ==(v1::SimpleVector, v2::SimpleVector)
     length(v1)==length(v2) || return false

test/show.jl

@@ -506,3 +506,6 @@ let io = IOBuffer()
     dump(io, :(x = 1))
     @test takebuf_string(io)[end] == '\n'
 end
+
+# issue #17338
+@test repr(Core.svec(1,2)) == "svec(1,2)"