Auto merge of #53356 - michaelwoerister:itlto, r=alexcrichton

Preliminary work for incremental ThinLTO (CGU name edition)

Bring back the first half of #52266 but hopefully without the performance regression.

src/runtest.rs

@@ -2209,12 +2209,12 @@ impl<'test> TestCx<'test> {
             .stdout
             .lines()
             .filter(|line| line.starts_with(PREFIX))
-            .map(str_to_mono_item)
+            .map(|line| str_to_mono_item(line, true))
             .collect();
 
         let expected: Vec<MonoItem> = errors::load_errors(&self.testpaths.file, None)
             .iter()
-            .map(|e| str_to_mono_item(&e.msg[..]))
+            .map(|e| str_to_mono_item(&e.msg[..], false))
             .collect();
 
         let mut missing = Vec::new();
@@ -2299,14 +2299,14 @@ impl<'test> TestCx<'test> {
         }
 
         // [MONO_ITEM] name [@@ (cgu)+]
-        fn str_to_mono_item(s: &str) -> MonoItem {
+        fn str_to_mono_item(s: &str, cgu_has_crate_disambiguator: bool) -> MonoItem {
             let s = if s.starts_with(PREFIX) {
                 (&s[PREFIX.len()..]).trim()
             } else {
                 s.trim()
             };
 
-            let full_string = format!("{}{}", PREFIX, s.trim().to_owned());
+            let full_string = format!("{}{}", PREFIX, s);
 
             let parts: Vec<&str> = s
                 .split(CGU_MARKER)
@@ -2323,7 +2323,13 @@ impl<'test> TestCx<'test> {
                     .split(' ')
                     .map(str::trim)
                     .filter(|s| !s.is_empty())
-                    .map(str::to_owned)
+                    .map(|s| {
+                        if cgu_has_crate_disambiguator {
+                            remove_crate_disambiguator_from_cgu(s)
+                        } else {
+                            s.to_string()
+                        }
+                    })
                     .collect()
             } else {
                 HashSet::new()
@@ -2348,6 +2354,23 @@ impl<'test> TestCx<'test> {
 
             string
         }
+
+        fn remove_crate_disambiguator_from_cgu(cgu: &str) -> String {
+            // The first '.' is the start of the crate disambiguator
+            let disambiguator_start = cgu.find('.')
+                .expect("Could not find start of crate disambiguator in CGU spec");
+
+            // The first non-alphanumeric character is the end of the disambiguator
+            let disambiguator_end = cgu[disambiguator_start + 1 ..]
+                .find(|c| !char::is_alphanumeric(c))
+                .expect("Could not find end of crate disambiguator in CGU spec")
+                + disambiguator_start + 1;
+
+            let mut result = cgu[0 .. disambiguator_start].to_string();
+            result.push_str(&cgu[disambiguator_end ..]);
+
+            result
+        }
     }
 
     fn init_incremental_test(&self) {