Deprecate the numpy repository (RobotLocomotion#14116)

Closes RobotLocomotion#8544.

tools/py_toolchain/BUILD.bazel

@@ -10,7 +10,7 @@ load(
 )
 
 # The value of interpreter_path must match the value of linux_interpreter_path
-# used when declaring the @numpy and @python repositories.
+# used when declaring the @python repository.
 py_runtime(
     name = "linux_py3_runtime",
     interpreter_path = LINUX_INTERPRETER_PATH,
@@ -50,7 +50,7 @@ toolchain(
 )
 
 # The value of interpreter_path must match the value of macos_interpreter_path
-# used when declaring the @numpy and @python repositories.
+# used when declaring the @python repository.
 py_runtime(
     name = "macos_py3_runtime",
     interpreter_path = MACOS_INTERPRETER_PATH,

tools/workspace/numpy/BUILD.bazel

@@ -1,8 +1,20 @@
 # -*- python -*-
 
-# This file exists to make our directory into a Bazel package, so that our
-# neighboring *.bzl file can be loaded elsewhere.
-
+load(
+    "@drake//tools/skylark:drake_cc.bzl",
+    "drake_cc_library",
+)
 load("//tools/lint:lint.bzl", "add_lint_tests")
 
+# This is only intended as regression test and will be removed on or after
+# 2021-01-01.
+drake_cc_library(
+    name = "stub",
+    srcs = ["stub.cc"],
+    deps = [
+        "@numpy//:numpy_for_stub_test",
+        "@python",
+    ],
+)
+
 add_lint_tests()

tools/workspace/numpy/repository.bzl

@@ -70,6 +70,15 @@ cc_library(
     hdrs = glob(["include/**"]),
     includes = ["include"],
     visibility = ["//visibility:public"],
+    deprecation = "DRAKE DEPRECATED: The @numpy repository is being removed from Drake on or after 2021-01-01. Downstream projects should add it to their own WORKSPACE if needed.", # noqa
+)
+
+# This is only intended for use by the regression test in
+# @drake//tools/workspace/numpy, and will be removed on or after 2021-01-01.
+cc_library(
+    name = "numpy_for_stub_test",
+    visibility = ["//visibility:public"],
+    deps = [":numpy"],
 )
     """
 

tools/workspace/numpy/stub.cc

@@ -0,0 +1,6 @@
+#include <numpy/npy_math.h>
+
+void stub() {
+  double x = npy_sin(0.0);
+  (void)x;
+}

tools/workspace/pybind11/package.BUILD.bazel

@@ -44,7 +44,6 @@ cc_library(
     includes = ["include"],
     deps = [
         "@eigen",
-        "@numpy",
         "@python",
     ],
 )