Deprecate using && and || within at-dot expressions (#26792)

Giving us space to allow lowering this to `.&&` and `.||` in the future. Ref #5187.

base/broadcast.jl

@@ -850,6 +850,11 @@ function __dot__(x::Expr)
            Meta.isexpr(x.args[1], :call) # function or macro definition
         Expr(x.head, x.args[1], dotargs[2])
     else
+        if x.head == :&& || x.head == :||
+            Base.depwarn("""
+                using $(x.head) expressions in @. is deprecated; in the future it will
+                become elementwise. Break the expression into smaller parts instead.""", nothing)
+        end
         head = string(x.head)
         if last(head) == '=' && first(head) != '.'
             Expr(Symbol('.',head), dotargs...)

base/deprecated.jl

@@ -82,11 +82,12 @@ function depwarn(msg, funcsym)
         _id=(frame,funcsym),
         _group=:depwarn,
         caller=caller,
-        maxlog=1
+        maxlog=funcsym === nothing ? nothing : 1
     )
     nothing
 end
 
+firstcaller(bt::Vector, ::Nothing) = Ptr{Cvoid}(0), StackTraces.UNKNOWN
 firstcaller(bt::Vector, funcsym::Symbol) = firstcaller(bt, (funcsym,))
 function firstcaller(bt::Vector, funcsyms)
     # Identify the calling line