Disallow multiple LHS assignment for one-line function definitions

[StephenVavasis]

Should one-line function definitions be allowed in multiple-LHS assignment statements? Julia (1.7.1) is inconsistent on this matter as the example below shows. My own opinion is that it should not be allowed, because there are too many weird corner cases if it is allowed.

julia> f(x),g(x)=3,5;

julia> f(12) + g('a')
8

julia> f(x),g(x)=x*x,x*x*x
ERROR: UndefVarError: x not defined
Stacktrace:
 [1] top-level scope
   @ REPL[22]:1

This issue was initially raised in discourse by Angel_Ramirez_Reyes: https://discourse.julialang.org/t/why-is-this-a-malformed-expression/86391/6