Replace truncate(0) with clear()

compiler/rustc_data_structures/src/obligation_forest/mod.rs

@@ -702,7 +702,7 @@ fn compress(&mut self, mut outcome_cb: impl FnMut(&O)) {
             self.apply_rewrites(&node_rewrites);
         }
 
-        node_rewrites.truncate(0);
+        node_rewrites.clear();
         self.reused_node_vec = node_rewrites;
     }
 

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -349,7 +349,7 @@ fn process_obligation(
         &mut self,
         pending_obligation: &mut PendingPredicateObligation<'tcx>,
     ) -> ProcessResult<PendingPredicateObligation<'tcx>, FulfillmentErrorCode<'tcx>> {
-        pending_obligation.stalled_on.truncate(0);
+        pending_obligation.stalled_on.clear();
 
         let obligation = &mut pending_obligation.obligation;
 

library/std/src/io/buffered/tests.rs

@@ -391,16 +391,16 @@ fn test_read_until() {
     let mut v = Vec::new();
     reader.read_until(0, &mut v).unwrap();
     assert_eq!(v, [0]);
-    v.truncate(0);
+    v.clear();
     reader.read_until(2, &mut v).unwrap();
     assert_eq!(v, [1, 2]);
-    v.truncate(0);
+    v.clear();
     reader.read_until(1, &mut v).unwrap();
     assert_eq!(v, [1]);
-    v.truncate(0);
+    v.clear();
     reader.read_until(8, &mut v).unwrap();
     assert_eq!(v, [0]);
-    v.truncate(0);
+    v.clear();
     reader.read_until(9, &mut v).unwrap();
     assert_eq!(v, []);
 }
@@ -429,13 +429,13 @@ fn test_read_line() {
     let mut s = String::new();
     reader.read_line(&mut s).unwrap();
     assert_eq!(s, "a\n");
-    s.truncate(0);
+    s.clear();
     reader.read_line(&mut s).unwrap();
     assert_eq!(s, "b\n");
-    s.truncate(0);
+    s.clear();
     reader.read_line(&mut s).unwrap();
     assert_eq!(s, "c");
-    s.truncate(0);
+    s.clear();
     reader.read_line(&mut s).unwrap();
     assert_eq!(s, "");
 }

library/std/src/io/tests.rs

@@ -17,10 +17,10 @@ fn read_until() {
     let mut v = Vec::new();
     assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 3);
     assert_eq!(v, b"123");
-    v.truncate(0);
+    v.clear();
     assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 1);
     assert_eq!(v, b"3");
-    v.truncate(0);
+    v.clear();
     assert_eq!(buf.read_until(b'3', &mut v).unwrap(), 0);
     assert_eq!(v, []);
 }
@@ -80,10 +80,10 @@ fn read_line() {
     let mut v = String::new();
     assert_eq!(buf.read_line(&mut v).unwrap(), 3);
     assert_eq!(v, "12\n");
-    v.truncate(0);
+    v.clear();
     assert_eq!(buf.read_line(&mut v).unwrap(), 1);
     assert_eq!(v, "\n");
-    v.truncate(0);
+    v.clear();
     assert_eq!(buf.read_line(&mut v).unwrap(), 0);
     assert_eq!(v, "");
 }

library/std/src/path.rs

@@ -1364,7 +1364,7 @@ fn _push(&mut self, path: &Path) {
 
         // absolute `path` replaces `self`
         if need_clear {
-            self.inner.truncate(0);
+            self.inner.clear();
 
         // verbatim paths need . and .. removed
         } else if comps.prefix_verbatim() && !path.inner.is_empty() {

library/std/src/sys/args/uefi.rs

@@ -93,7 +93,7 @@ fn parse_lp_cmd_line(code_units: &[u16]) -> Option<Vec<OsString>> {
             // If not `in_quotes`, a space or tab ends the argument.
             SPACE if !in_quotes => {
                 ret_val.push(OsString::from(&cur[..]));
-                cur.truncate(0);
+                cur.clear();
 
                 // Skip whitespace.
                 while code_units_iter.next_if_eq(&Ok(SPACE)).is_some() {}

library/std/src/sys/args/windows.rs

@@ -106,7 +106,7 @@ fn parse_lp_cmd_line<'a, F: Fn() -> OsString>(
             // If not `in_quotes`, a space or tab ends the argument.
             SPACE | TAB if !in_quotes => {
                 ret_val.push(OsString::from_wide(&cur[..]));
-                cur.truncate(0);
+                cur.clear();
 
                 // Skip whitespace.
                 code_units.advance_while(|w| w == SPACE || w == TAB);

src/tools/compiletest/src/runtest/debuginfo.rs

@@ -191,7 +191,7 @@ fn run_debuginfo_gdb_test(&self) {
             let mut stdout = BufReader::new(adb.stdout.take().unwrap());
             let mut line = String::new();
             loop {
-                line.truncate(0);
+                line.clear();
                 stdout.read_line(&mut line).unwrap();
                 if line.starts_with("Listening on port 5039") {
                     break;

src/tools/remote-test-server/src/main.rs

@@ -211,12 +211,12 @@ fn handle_run(socket: TcpStream, work: &Path, tmp: &Path, lock: &Mutex<()>, conf
     let mut args = Vec::new();
     while t!(reader.read_until(0, &mut arg)) > 1 {
         args.push(t!(str::from_utf8(&arg[..arg.len() - 1])).to_string());
-        arg.truncate(0);
+        arg.clear();
     }
 
     // Next we'll get a bunch of env vars in pairs delimited by 0s as well
     let mut env = Vec::new();
-    arg.truncate(0);
+    arg.clear();
     while t!(reader.read_until(0, &mut arg)) > 1 {
         let key_len = arg.len() - 1;
         let val_len = t!(reader.read_until(0, &mut arg)) - 1;
@@ -227,7 +227,7 @@ fn handle_run(socket: TcpStream, work: &Path, tmp: &Path, lock: &Mutex<()>, conf
             let val = t!(str::from_utf8(val)).to_string();
             env.push((key, val));
         }
-        arg.truncate(0);
+        arg.clear();
     }
 
     // The section of code from here down to where we drop the lock is going to