Run miri

To spare CI resources, only doc tests are run there.
And some non-doc tests are so slow with miri that I don't even want
to run them locally.

.cirrus.yml

@@ -72,6 +72,7 @@ task:
   # rustc version is so likely to have changed that build artefacts are not worth caching
   setup_script:
     - cargo install cargo-fuzz
+    - rustup component add miri
   info_script:
     - rustc --version
   check_script:
@@ -81,6 +82,9 @@ task:
     - cargo build --benches --all-features
     - cargo fuzz build
     # fuzz supports feature selection,
-    # but --no-default-features doesn't seem to have any effect.
+    # but --no-default-features doesn't seem to have any effect
+  test_script:
+    # the doc tets are fast and should cover a lot of code
+    - cargo miri test --all-features --doc -- --test-threads=1
   before_cache_script:
     - rm -rf $HOME/.cargo/registry/index

do.sh

@@ -9,7 +9,7 @@ if [[ ${1:0:1} == - || $1 == help ]] || (( $# > 1 )); then
     echo "A script to make it easy to check & lint & test everything." >&2
     echo "It assumes rustup is installed and that cargo +release works." >&2
     echo >&2
-    echo "Usage: $0 ([setup|MSRV|check|test|ignored|clippy|fuzz|bench|shellcheck|help])" >&2
+    echo "Usage: $0 ([setup|MSRV|check|test|ignored|clippy|miri|fuzz|bench|shellcheck|help])" >&2
     echo "If no argument is provided, all parts except ignored and help are run," >&2
     echo "but setup is only done if auto-detection fails." >&2
     exit 1
@@ -55,6 +55,15 @@ if [[ -z $1 || $1 == clippy ]]; then
     cargo +nightly clippy --all-features --tests --benches --examples
 fi
 
+# miri, nightly
+if [[ $1 == setup ]] || ! cargo +nightly help miri >/dev/null 2>/dev/null; then
+    rustup component add miri --toolchain nightly
+    cargo +nightly miri setup
+fi
+if [[ -z $1 || $1 == miri ]]; then
+    cargo +nightly miri test --all-features -- --quiet
+fi
+
 # fuzzing tests, nightly
 if [[ $1 == setup ]] || ! command -V cargo-fuzz >/dev/null 2>/dev/null; then
     cargo +nightly install cargo-fuzz

tests/errs.rs

@@ -67,7 +67,9 @@ fn kind<T>(result: Result<T,Utf8Error>) -> Result<T,Utf8ErrorKind> {
     }
 }
 
-#[test] fn utf16_extra_unit() {
+#[test]
+#[cfg_attr(miri, ignore)]
+fn utf16_extra_unit() {
     for c in 0..0x1_00_00 {
         assert_eq!( (c as u16).utf16_needs_extra_unit(), match c {
             0b_0000_0000_0000_0000..=0b_1101_0111_1111_1111 => Ok(false),
@@ -80,7 +82,9 @@ fn kind<T>(result: Result<T,Utf8Error>) -> Result<T,Utf8ErrorKind> {
 }
 
 
-#[test] fn from_utf16_tuple() {
+#[test]
+#[cfg_attr(miri, ignore)]
+fn from_utf16_tuple() {
     use encode_unicode::error::InvalidUtf16Tuple::*;
     for u in 0xdc00..0xe000 {
         let close = if u%3==0 {u-100} else {u+100};

tests/exhaustive.rs

@@ -24,6 +24,7 @@ fn from_ascii() {
 }
 
 #[test]
+#[cfg_attr(miri, ignore)]
 fn from_bmp() {
     for cp in 0u32..0x1_00_00 {
         assert_eq!(