Malformed let* statements get accepted when inside methods

[Patrick Poitras]

Hello all,

Bit of a weird bug. In processing defmethod, some malformed let* statements are accepted as valid.

For example, let's say I have the following defun:

(defun print-1 ()
  (let* ((a 1 t))
    a))

The compilation of this function returns an error that states `The LET binding spec (A 1 T) is malformed.`

The same thing happens if I try to compile this lambda function.

(lambda ()
  (let* ((a 1 t))
    a))

However, if I have an arbitrary class,

(defclass arbitrary-object () ())

and try to define the following method

(defmethod print-1 ((obj arbitrary-object))
  (let* ((a 1 t))
    a))

Then the function compiles successfully. It is of note that the same method with a "let" instead of "let*" will fail to compile. This also happens with :method inside a defgeneric.

Thanks

SBCL 2.2.7

Linux ppoitras 4.15.0-192-generic #203-Ubuntu SMP Wed Aug 10 17:40:03 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

PS. Priority from my POV is low. We've encountered it once inside our codebase, but the result of macroexpansion just results in a truncated (a 1 t) to (a 1). We haven't seen it cause issues as of yet.