pkg_config: Add extra_deprecation option

tools/workspace/pkg_config.BUILD.tpl

@@ -15,6 +15,7 @@ cc_library(
     includes = %{includes},
     linkopts = %{linkopts},
     deps = %{deps},
+    deprecation = %{extra_deprecation},
 )
 
 %{build_epilog}

tools/workspace/pkg_config.bzl

@@ -221,6 +221,14 @@ def setup_pkg_config_repository(repository_ctx):
         includes += ["include/" + symlink_dest]
     hdrs_prologue = "glob([\"include/**\"]) + "
 
+    extra_deprecation = getattr(
+        repository_ctx.attr,
+        "extra_deprecation",
+        "",
+    )
+    if extra_deprecation == "":
+        extra_deprecation = None
+
     # Write out the BUILD.bazel file.
     substitutions = {
         "%{topcomment}": "DO NOT EDIT: generated by pkg_config_repository()",
@@ -254,6 +262,7 @@ def setup_pkg_config_repository(repository_ctx):
             getattr(repository_ctx.attr, "extra_deps", []),
         ),
         "%{build_epilog}": getattr(repository_ctx.attr, "build_epilog", ""),
+        "%{extra_deprecation}": repr(extra_deprecation),
     }
     template = getattr(
         repository_ctx.attr,
@@ -295,6 +304,7 @@ pkg_config_repository = repository_rule(
         "extra_deps": attr.string_list(),
         "build_epilog": attr.string(),
         "pkg_config_paths": attr.string_list(),
+        "extra_deprecation": attr.string(),
     },
     local = True,
     configure = True,
@@ -345,4 +355,6 @@ Args:
     pkg_config_paths: (Optional) Paths to find pkg-config files (.pc). Note
                       that we ignore the environment variable PKG_CONFIG_PATH
                       set by the user.
+    extra_deprecation: (Optional) Add a deprecation message to the library
+                       BUILD target.
 """