Disallow toolstate regression at the last week of the 6-week cycle.

src/ci/docker/x86_64-gnu-tools/Dockerfile

@@ -17,6 +17,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+COPY x86_64-gnu-tools/checkregression.py /tmp/
 COPY x86_64-gnu-tools/checktools.sh /tmp/
 COPY x86_64-gnu-tools/repo.sh /tmp/
 

src/ci/docker/x86_64-gnu-tools/checkregression.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution and at
+# http://rust-lang.org/COPYRIGHT.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+import sys
+import json
+
+if __name__ == '__main__':
+    os_name = sys.argv[1]
+    toolstate_file = sys.argv[2]
+    current_state = sys.argv[3]
+
+    with open(toolstate_file, 'r') as f:
+        toolstate = json.load(f)
+    with open(current_state, 'r') as f:
+        current = json.load(f)
+
+    regressed = False
+    for cur in current:
+        tool = cur['tool']
+        state = cur[os_name]
+        new_state = toolstate.get(tool, '')
+        if new_state < state:
+            print(
+                'Error: The state of "{}" has regressed from "{}" to "{}"'
+                .format(tool, state, new_state)
+            )
+            regressed = True
+
+    if regressed:
+        sys.exit(1)

src/ci/docker/x86_64-gnu-tools/checktools.sh

@@ -17,6 +17,9 @@ TOOLSTATE_FILE="$(realpath $2)"
 OS="$3"
 COMMIT="$(git rev-parse HEAD)"
 CHANGED_FILES="$(git diff --name-status HEAD HEAD^)"
+SIX_WEEK_CYCLE="$(( ($(date +%s) / 604800 - 3) % 6 ))"
+# ^ 1970 Jan 1st is a Thursday, and our release dates are also on Thursdays,
+#   thus we could divide by 604800 (7 days in seconds) directly.
 
 touch "$TOOLSTATE_FILE"
 
@@ -59,6 +62,11 @@ if [ "$RUST_RELEASE_CHANNEL" = nightly -a -n "${TOOLSTATE_REPO_ACCESS_TOKEN+is_s
         sed -i "1 a\\
 $COMMIT\t$(cat "$TOOLSTATE_FILE")
 " "history/$OS.tsv"
+    # if we are at the last week in the 6-week release cycle, reject any kind of regression.
+    if [ $SIX_WEEK_CYCLE -eq 5 ]; then
+        python2.7 "$(dirname $0)/checkregression.py" \
+            "$OS" "$TOOLSTATE_FILE" "rust-toolstate/_data/latest.json"
+    fi
     rm -f "$MESSAGE_FILE"
     exit 0
 fi