Auto merge of #2320 - RalfJung:less-rebuilds, r=RalfJung

reduce regex features to reduce rebuilds

Helps with the issue I [mentioned on Zulip](https://rust-lang.zulipchat.com/#narrow/stream/269128-miri/topic/Miri.20rebuilds/near/287442340).

Cargo.toml

@@ -39,7 +39,8 @@ libc = "0.2"
 [dev-dependencies]
 colored = "2"
 ui_test = { path = "ui_test" }
-regex = "1.5.5"
+# Features chosen to match those required by env_logger, to avoid rebuilds
+regex = { version = "1.5.5", default-features = false, features = ["perf", "std"] }
 lazy_static = "1.4.0"
 
 [package.metadata.rust-analyzer]

ui_test/Cargo.toml

@@ -10,7 +10,8 @@ doctest = false # but no doc tests
 [dependencies]
 rustc_version = "0.4"
 colored = "2"
-regex = "1.5.5"
+# Features chosen to match those required by env_logger, to avoid rebuilds
+regex = { version = "1.5.5", default-features = false, features = ["perf", "std"] }
 pretty_assertions = "1.2.1"
 crossbeam = "0.8.1"
 lazy_static = "1.4.0"

ui_test/src/comments.rs

@@ -75,7 +75,7 @@ pub(crate) fn parse_file(path: &Path) -> Self {
     pub(crate) fn parse(path: &Path, content: &str) -> Self {
         let mut this = Self::default();
         let error_pattern_regex =
-            Regex::new(r"//(\[(?P<revision>[^\]]+)\])?~(?P<offset>\||[\^]+)?\s*(?P<level>ERROR|HELP|WARN|NOTE)?:?(?P<text>.*)")
+            Regex::new(r"//(\[(?P<revision>[^\]]+)\])?~(?P<offset>\||[\^]+)? *(?P<level>ERROR|HELP|WARN|NOTE)?:?(?P<text>.*)")
                 .unwrap();
 
         // The line that a `|` will refer to

ui_test/src/rustc_stderr.rs

@@ -116,7 +116,7 @@ fn line(&self, file: &Path) -> Option<usize> {
 }
 
 pub(crate) fn filter_annotations_from_rendered(rendered: &str) -> std::borrow::Cow<'_, str> {
-    let annotations = Regex::new(r"\s*//(\[[^\]]\])?~.*").unwrap();
+    let annotations = Regex::new(r" *//(\[[^\]]\])?~.*").unwrap();
     annotations.replace_all(rendered, "")
 }