MAKE-ARRAY makes the unexpected array element type upgrade

[Roman Marynchak]

This form

(make-array 8 :element-type 'foo)

surprisingly returns #(0 0 0 0 0 0 0 0) instead of claiming about the undefined type specifier FOO.

One may think that this is a kind of an implicit array element type upgrade to T... But why this form

(upgraded-array-element-type 'foo)

claims about the undefined type FOO instead of returning T in this case?

I think that MAKE-ARRAY should verify :element-type value to be a valid type specifier.

[Nikodemus Siivola (nikodemus)]

Without checking CLHS requirements, this seems sensible.

[Douglas Katzman (dougk)]

CLHS mentions "Exceptional Situations: None." for MAKE-ARRAY.
Of course, CLHS mentions no exceptional situations for UPGRADED-ARRAY-ELEMENT-TYPE either.
Probably it should be STYLE-WARNING if detected at compile-time and an error at runtime.