diff --git a/.cspell.json b/.cspell.json
index b11d0b40..81734c25 100644
--- a/.cspell.json
+++ b/.cspell.json
@@ -26,7 +26,7 @@
   ],
   "ignoreRegExpList": [
     // Copyright notice
-    "Copyright ((\\(c\\)|\\(C\\)|©) )?.*",
+    "Copyright .*",
     // GHA actions/workflows
     "uses: .+@",
     // GHA context (repo name, owner name, etc.)
@@ -35,6 +35,8 @@
     "( |\\[)@[\\w_-]+",
     // Git config username
     "git config user.name .*",
+    // Username in todo comment
+    "(TODO|FIXME)\\([\\w_., -]+\\)",
     // Cargo.toml authors
     "authors *= *\\[.*\\]",
     "\".* <[\\w_.+-]+@[\\w.-]+>\""
diff --git a/.github/.cspell/organization-dictionary.txt b/.github/.cspell/organization-dictionary.txt
index 558844c4..b9ff7bda 100644
--- a/.github/.cspell/organization-dictionary.txt
+++ b/.github/.cspell/organization-dictionary.txt
@@ -85,6 +85,7 @@ acqrel
 alloc
 bools
 builtins
+bytecount
 canonicalize
 consts
 ctypes
@@ -98,6 +99,7 @@ inlateout
 intrinsics
 lateout
 mclass
+memcpy
 msrv
 nand
 nomem
@@ -110,6 +112,7 @@ rclass
 repr
 rfind
 rfold
+rposition
 rsplit
 rustlib
 seqcst
@@ -124,6 +127,8 @@ unsized
 upcastable
 
 // Other
+armel
+armhf
 binutils
 connrefused
 cygwin
diff --git a/tools/tidy.sh b/tools/tidy.sh
index 73c4d48a..56e2a903 100755
--- a/tools/tidy.sh
+++ b/tools/tidy.sh
@@ -41,6 +41,14 @@ warn() {
     fi
     should_fail=1
 }
+error() {
+    if [[ -n "${GITHUB_ACTIONS:-}" ]]; then
+        echo "::error::$*"
+    else
+        echo >&2 "error: $*"
+    fi
+    should_fail=1
+}
 
 if [[ $# -gt 0 ]]; then
     cat <<EOF
@@ -70,6 +78,11 @@ if [[ -n "$(git ls-files '*.rs')" ]]; then
     else
         warn "'rustup' is not installed"
     fi
+    cast_without_turbofish=$(grep -n -E '\.cast\(\)' $(git ls-files '*.rs') || true)
+    if [[ -n "${cast_without_turbofish}" ]]; then
+        error "please replace \`.cast()\` with \`.cast::<type_name>()\`:"
+        echo "${cast_without_turbofish}"
+    fi
 fi
 
 # C/C++ (if exists)
@@ -103,8 +116,8 @@ if [[ -n "$(git ls-files '*.yml')$(git ls-files '*.js')$(git ls-files '*.json')"
                 permissions=$(yq '.permissions' "${workflow}" | jq -c)
                 case "${permissions}" in
                     '{"contents":"read"}' | '{"contents":"none"}' | '{}') ;;
-                    null) warn "${workflow}: top level permissions not found; it must be 'contents: read' or weaker permissions" ;;
-                    *) warn "${workflow}: only 'contents: read' and weaker permissions are allowed at top level; if you want to use stronger permissions, please set job-level permissions" ;;
+                    null) error "${workflow}: top level permissions not found; it must be 'contents: read' or weaker permissions" ;;
+                    *) error "${workflow}: only 'contents: read' and weaker permissions are allowed at top level; if you want to use stronger permissions, please set job-level permissions" ;;
                 esac
                 # Make sure the 'needs' section is not out of date.
                 if grep -q '# tidy:needs' "${workflow}" && ! grep -Eq '# *needs: \[' "${workflow}"; then
@@ -117,7 +130,7 @@ if [[ -n "$(git ls-files '*.yml')$(git ls-files '*.js')$(git ls-files '*.json')"
                         printf -v jobs '%s, ' "${jobs_actual[@]}"
                         sed -i "s/needs: \[.*\] # tidy:needs/needs: [${jobs%, }] # tidy:needs/" "${workflow}"
                         check_diff "${workflow}"
-                        warn "${workflow}: please update 'needs' section in 'ci-success' job"
+                        error "${workflow}: please update 'needs' section in 'ci-success' job"
                     fi
                 fi
             done
@@ -127,7 +140,7 @@ if [[ -n "$(git ls-files '*.yml')$(git ls-files '*.js')$(git ls-files '*.json')"
     fi
 fi
 if [[ -n "$(git ls-files '*.yaml')" ]]; then
-    warn "please use '.yml' instead of '.yaml' for consistency"
+    error "please use '.yml' instead of '.yaml' for consistency"
     git ls-files '*.yaml'
 fi
 
@@ -199,7 +212,7 @@ EOF
             fi
             dup=$(sed '/^$/d' .github/.cspell/project-dictionary.txt "${dictionary}" | LC_ALL=C sort -f | uniq -d -i | (grep -v '//.*' || true))
             if [[ -n "${dup}" ]]; then
-                warn "duplicated words in dictionaries; please remove the following words from .github/.cspell/project-dictionary.txt"
+                error "duplicated words in dictionaries; please remove the following words from .github/.cspell/project-dictionary.txt"
                 echo "======================================="
                 echo "${dup}"
                 echo "======================================="