Deprecate the Stream and Genlex stdlib modules (#10482)

The core OCaml development team decided to remove the Stream and Genlex modules from the standard library, making them available in a separate library camlp-streams instead.

To ease the transition, this commit adds a "deprecated" alert to the Stream and Genlex stdlib modules.  Actual removal will take place one or two major releases later.

Changes

@@ -15,6 +15,11 @@ Working version
   is actually a suffix of `name` and raises Invalid_argument otherwise.
   (Xavier Leroy, report by whitequark, review by David Allsopp)
 
+* #10482: mark the Stream and Genlex modules as deprecated, in preparation
+  for a future removal.  These modules (without deprecation alert)
+  are now provided by the camlp-streams library.
+  (Xavier Leroy, review by Nicolás Ojeda Bär)
+
 ### Other libraries:
 
 - #10192: Add support for Unix domain sockets on Windows and use them

stdlib/Compflags

@@ -37,5 +37,7 @@ case $1 in
   stdlib__Float.cm[ox]) echo ' -nolabels -no-alias-deps';;
   stdlib__Oo.cmi) echo ' -no-principal';;
     # preserve structure sharing in Oo.copy (PR#9767)
+  stdlib__Genlex.cm[iox]) echo ' -w -3';;
+    # ignore the "deprecated" alert on the Stream module
   *) echo ' ';;
 esac

stdlib/stdlib.mli

@@ -1397,6 +1397,7 @@ module Format       = Format
 module Fun          = Fun
 module Gc           = Gc
 module Genlex       = Genlex
+[@@deprecated "Use the camlp-streams library instead."]
 module Hashtbl      = Hashtbl
 module Int          = Int
 module Int32        = Int32
@@ -1429,6 +1430,7 @@ module Set          = Set
 module Stack        = Stack
 module StdLabels    = StdLabels
 module Stream       = Stream
+[@@deprecated "Use the camlp-streams library instead."]
 module String       = String
 module StringLabels = StringLabels
 module Sys          = Sys

testsuite/tests/lib-stream/count_concat_bug.ml

@@ -1,4 +1,5 @@
 (* TEST
+   flags = "-w -3"
    include testing
 *)
 

testsuite/tests/lib-stream/mpr7769.ml

@@ -1,4 +1,5 @@
 (* TEST
+   flags = "-w -3"
    readonly_files = "mpr7769.txt"
 *)