Fix improper FFTW function deprecation

Author: ararslan

base/deprecated.jl

@@ -1438,15 +1438,24 @@ export Operators
 # This mimics the structure as it was defined in Base to avoid directly breaking code
 # that assumes this structure
 module DFT
-    for f in [:bfft, :bfft!, :brfft, :dct, :dct!, :fft, :fft!, :fftshift, :idct, :idct!,
-              :ifft, :ifft!, :ifftshift, :irfft, :plan_bfft, :plan_bfft!, :plan_brfft,
+    for f in [:fftshift, :ifftshift]
+        @eval begin
+            function $f(args...; kwargs...)
+                error($f, " has been moved to the package AbstractFFTs.jl.\n",
+                      "Run `Pkg.add(\"AbstractFFTs\")` to install AbstractFFTs then run ",
+                      "`using AbstractFFTs` to load it.")
+            end
+            export $f
+        end
+    end
+    for f in [:bfft, :bfft!, :brfft, :dct, :dct!, :fft, :fft!, :idct, :idct!,
+              :ifft, :ifft!, :irfft, :plan_bfft, :plan_bfft!, :plan_brfft,
               :plan_dct, :plan_dct!, :plan_fft, :plan_fft!, :plan_idct, :plan_idct!,
               :plan_ifft, :plan_ifft!, :plan_irfft, :plan_rfft, :rfft]
-        pkg = endswith(String(f), "shift") ? "AbstractFFTs" : "FFTW"
         @eval begin
             function $f(args...; kwargs...)
-                error($f, " has been moved to the package $pkg.jl.\n",
-                      "Run `Pkg.add(\"$pkg\")` to install $pkg then run `using $pkg` ",
+                error($f, " has been moved to the package FFTW.jl.\n",
+                      "Run `Pkg.add(\"FFTW\")` to install FFTW then run `using FFTW` ",
                       "to load it.")
             end
             export $f