Auto merge of #46602 - mbrubeck:try, r=kennytm

Replace option_try macros and match with ? operator

None

src/liballoc/allocator.rs

@@ -217,14 +217,8 @@ impl Layout {
     /// On arithmetic overflow, returns `None`.
     #[inline]
     pub fn repeat(&self, n: usize) -> Option<(Self, usize)> {
-        let padded_size = match self.size.checked_add(self.padding_needed_for(self.align)) {
-            None => return None,
-            Some(padded_size) => padded_size,
-        };
-        let alloc_size = match padded_size.checked_mul(n) {
-            None => return None,
-            Some(alloc_size) => alloc_size,
-        };
+        let padded_size = self.size.checked_add(self.padding_needed_for(self.align))?;
+        let alloc_size = padded_size.checked_mul(n)?;
 
         // We can assume that `self.align` is a power-of-two that does
         // not exceed 2<sup>31</sup>. Furthermore, `alloc_size` has already been
@@ -246,26 +240,14 @@ impl Layout {
     /// On arithmetic overflow, returns `None`.
     pub fn extend(&self, next: Self) -> Option<(Self, usize)> {
         let new_align = cmp::max(self.align, next.align);
-        let realigned = match Layout::from_size_align(self.size, new_align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let realigned = Layout::from_size_align(self.size, new_align)?;
 
         let pad = realigned.padding_needed_for(next.align);
 
-        let offset = match self.size.checked_add(pad) {
-            None => return None,
-            Some(offset) => offset,
-        };
-        let new_size = match offset.checked_add(next.size) {
-            None => return None,
-            Some(new_size) => new_size,
-        };
+        let offset = self.size.checked_add(pad)?;
+        let new_size = offset.checked_add(next.size)?;
 
-        let layout = match Layout::from_size_align(new_size, new_align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let layout = Layout::from_size_align(new_size, new_align)?;
         Some((layout, offset))
     }
 
@@ -282,11 +264,7 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `None`.
     pub fn repeat_packed(&self, n: usize) -> Option<Self> {
-        let size = match self.size().checked_mul(n) {
-            None => return None,
-            Some(scaled) => scaled,
-        };
-
+        let size = self.size().checked_mul(n)?;
         Layout::from_size_align(size, self.align)
     }
 
@@ -306,14 +284,8 @@ impl Layout {
     ///
     /// On arithmetic overflow, returns `None`.
     pub fn extend_packed(&self, next: Self) -> Option<(Self, usize)> {
-        let new_size = match self.size().checked_add(next.size()) {
-            None => return None,
-            Some(new_size) => new_size,
-        };
-        let layout = match Layout::from_size_align(new_size, self.align) {
-            None => return None,
-            Some(l) => l,
-        };
+        let new_size = self.size().checked_add(next.size())?;
+        let layout = Layout::from_size_align(new_size, self.align)?;
         Some((layout, self.size()))
     }
 

src/liballoc/btree/set.rs

@@ -1067,21 +1067,15 @@ impl<'a, T: Ord> Iterator for Intersection<'a, T> {
 
     fn next(&mut self) -> Option<&'a T> {
         loop {
-            let o_cmp = match (self.a.peek(), self.b.peek()) {
-                (None, _) => None,
-                (_, None) => None,
-                (Some(a1), Some(b1)) => Some(a1.cmp(b1)),
-            };
-            match o_cmp {
-                None => return None,
-                Some(Less) => {
+            match Ord::cmp(self.a.peek()?, self.b.peek()?) {
+                Less => {
                     self.a.next();
                 }
-                Some(Equal) => {
+                Equal => {
                     self.b.next();
                     return self.a.next();
                 }
-                Some(Greater) => {
+                Greater => {
                     self.b.next();
                 }
             }

src/liballoc/string.rs

@@ -1044,10 +1044,7 @@ impl String {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn pop(&mut self) -> Option<char> {
-        let ch = match self.chars().rev().next() {
-            Some(ch) => ch,
-            None => return None,
-        };
+        let ch = self.chars().rev().next()?;
         let newlen = self.len() - ch.len_utf8();
         unsafe {
             self.vec.set_len(newlen);

src/liballoc/vec.rs

@@ -1423,10 +1423,7 @@ impl<T: PartialEq> Vec<T> {
     /// ```
     #[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")]
     pub fn remove_item(&mut self, item: &T) -> Option<T> {
-        let pos = match self.iter().position(|x| *x == *item) {
-            Some(x) => x,
-            None => return None,
-        };
+        let pos = self.iter().position(|x| *x == *item)?;
         Some(self.remove(pos))
     }
 }

src/libcore/str/mod.rs

@@ -494,11 +494,10 @@ fn unwrap_or_0(opt: Option<&u8>) -> u8 {
 #[inline]
 pub fn next_code_point<'a, I: Iterator<Item = &'a u8>>(bytes: &mut I) -> Option<u32> {
     // Decode UTF-8
-    let x = match bytes.next() {
-        None => return None,
-        Some(&next_byte) if next_byte < 128 => return Some(next_byte as u32),
-        Some(&next_byte) => next_byte,
-    };
+    let x = *bytes.next()?;
+    if x < 128 {
+        return Some(x as u32)
+    }
 
     // Multibyte case follows
     // Decode from a byte combination out of: [[[x y] z] w]

src/librustc/hir/map/mod.rs

@@ -978,9 +978,8 @@ impl<'a, 'hir> NodesMatchingSuffix<'a, 'hir> {
         // chain, then returns `None`.
         fn find_first_mod_parent<'a>(map: &'a Map, mut id: NodeId) -> Option<(NodeId, Name)> {
             loop {
-                match map.find(id) {
-                    None => return None,
-                    Some(NodeItem(item)) if item_is_mod(&item) =>
+                match map.find(id)? {
+                    NodeItem(item) if item_is_mod(&item) =>
                         return Some((id, item.name)),
                     _ => {}
                 }

src/librustc/infer/error_reporting/util.rs

@@ -91,10 +91,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                         .iter()
                         .enumerate()
                         .filter_map(|(index, arg)| {
-                            let ty = match tables.borrow().node_id_to_type_opt(arg.hir_id) {
-                                Some(v) => v,
-                                None => return None, // sometimes the tables are not yet populated
-                            };
+                            // May return None; sometimes the tables are not yet populated.
+                            let ty = tables.borrow().node_id_to_type_opt(arg.hir_id)?;
                             let mut found_anon_region = false;
                             let new_arg_ty = self.tcx
                                 .fold_regions(&ty, &mut false, |r, _| if *r == *anon_region {

src/librustc/ty/util.rs

@@ -439,12 +439,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             }
         });
 
-        let dtor_did = match dtor_did {
-            Some(dtor) => dtor,
-            None => return None,
-        };
-
-        Some(ty::Destructor { did: dtor_did })
+        Some(ty::Destructor { did: dtor_did? })
     }
 
     /// Return the set of types that are required to be alive in

src/librustc/util/common.rs

@@ -215,12 +215,6 @@ pub fn record_time<T, F>(accu: &Cell<Duration>, f: F) -> T where
     rv
 }
 
-// Like std::macros::try!, but for Option<>.
-#[cfg(unix)]
-macro_rules! option_try(
-    ($e:expr) => (match $e { Some(e) => e, None => return None })
-);
-
 // Memory reporting
 #[cfg(unix)]
 fn get_resident() -> Option<usize> {
@@ -228,11 +222,11 @@ fn get_resident() -> Option<usize> {
     use std::io::Read;
 
     let field = 1;
-    let mut f = option_try!(File::open("/proc/self/statm").ok());
+    let mut f = File::open("/proc/self/statm").ok()?;
     let mut contents = String::new();
-    option_try!(f.read_to_string(&mut contents).ok());
-    let s = option_try!(contents.split_whitespace().nth(field));
-    let npages = option_try!(s.parse::<usize>().ok());
+    f.read_to_string(&mut contents).ok()?;
+    let s = contents.split_whitespace().nth(field)?;
+    let npages = s.parse::<usize>().ok()?;
     Some(npages * 4096)
 }
 

src/librustc_data_structures/indexed_set.rs

@@ -291,10 +291,8 @@ impl<'a, T: Idx> Iterator for Iter<'a, T> {
                 }
             }
 
-            match self.iter.next() {
-                Some((i, word)) => self.cur = Some((*word, word_bits * i)),
-                None => return None,
-            }
+            let (i, word) = self.iter.next()?;
+            self.cur = Some((*word, word_bits * i));
         }
     }
 }

src/librustc_metadata/creader.rs

@@ -385,10 +385,7 @@ impl<'a> CrateLoader<'a> {
     }
 
     fn load(&mut self, locate_ctxt: &mut locator::Context) -> Option<LoadResult> {
-        let library = match locate_ctxt.maybe_load_library_crate() {
-            Some(lib) => lib,
-            None => return None,
-        };
+        let library = locate_ctxt.maybe_load_library_crate()?;
 
         // In the case that we're loading a crate, but not matching
         // against a hash, we could load a crate which has the same hash

src/librustc_mir/borrow_check/mod.rs

@@ -1982,10 +1982,7 @@ mod prefixes {
     impl<'cx, 'gcx, 'tcx> Iterator for Prefixes<'cx, 'gcx, 'tcx> {
         type Item = &'cx Place<'tcx>;
         fn next(&mut self) -> Option<Self::Item> {
-            let mut cursor = match self.next {
-                None => return None,
-                Some(place) => place,
-            };
+            let mut cursor = self.next?;
 
             // Post-processing `place`: Enqueue any remaining
             // work. Also, `place` may not be a prefix itself, but

src/librustc_trans/back/archive.rs

@@ -120,10 +120,7 @@ impl<'a> ArchiveBuilder<'a> {
         if let Some(ref a) = self.src_archive {
             return a.as_ref()
         }
-        let src = match self.config.src {
-            Some(ref src) => src,
-            None => return None,
-        };
+        let src = self.config.src.as_ref()?;
         self.src_archive = Some(ArchiveRO::open(src).ok());
         self.src_archive.as_ref().unwrap().as_ref()
     }

src/librustc_typeck/check/autoderef.rs

@@ -79,10 +79,8 @@ impl<'a, 'gcx, 'tcx> Iterator for Autoderef<'a, 'gcx, 'tcx> {
         let (kind, new_ty) = if let Some(mt) = self.cur_ty.builtin_deref(false, NoPreference) {
             (AutoderefKind::Builtin, mt.ty)
         } else {
-            match self.overloaded_deref_ty(self.cur_ty) {
-                Some(ty) => (AutoderefKind::Overloaded, ty),
-                _ => return None,
-            }
+            let ty = self.overloaded_deref_ty(self.cur_ty)?;
+            (AutoderefKind::Overloaded, ty)
         };
 
         if new_ty.references_error() {
@@ -108,10 +106,7 @@ impl<'a, 'gcx, 'tcx> Autoderef<'a, 'gcx, 'tcx> {
 
         // <cur_ty as Deref>
         let trait_ref = TraitRef {
-            def_id: match tcx.lang_items().deref_trait() {
-                Some(f) => f,
-                None => return None,
-            },
+            def_id: tcx.lang_items().deref_trait()?,
             substs: tcx.mk_substs_trait(self.cur_ty, &[]),
         };
 

src/librustdoc/html/format.rs

@@ -425,16 +425,14 @@ pub fn href(did: DefId) -> Option<(String, ItemType, Vec<String>)> {
         Some(&(ref fqp, shortty)) => {
             (fqp, shortty, repeat("../").take(loc.len()).collect())
         }
-        None => match cache.external_paths.get(&did) {
-            Some(&(ref fqp, shortty)) => {
+        None => {
+            let &(ref fqp, shortty) = cache.external_paths.get(&did)?;
             (fqp, shortty, match cache.extern_locations[&did.krate] {
                 (.., render::Remote(ref s)) => s.to_string(),
                 (.., render::Local) => repeat("../").take(loc.len()).collect(),
                 (.., render::Unknown) => return None,
             })
         }
-            None => return None,
-        }
     };
     for component in &fqp[..fqp.len() - 1] {
         url.push_str(component);

src/librustdoc/html/render.rs

@@ -1672,11 +1672,8 @@ impl<'a> Item<'a> {
         let mut path = String::new();
         let (krate, path) = if self.item.def_id.is_local() {
             let path = PathBuf::from(&self.item.source.filename);
-            if let Some(path) = self.cx.shared.local_sources.get(&path) {
+            let path = self.cx.shared.local_sources.get(&path)?;
             (&self.cx.shared.layout.krate, path)
-            } else {
-                return None;
-            }
         } else {
             // Macros from other libraries get special filenames which we can
             // safely ignore.

src/libserialize/json.rs

@@ -1052,10 +1052,7 @@ impl Json {
     pub fn find_path<'a>(&'a self, keys: &[&str]) -> Option<&'a Json>{
         let mut target = self;
         for key in keys {
-            match target.find(*key) {
-                Some(t) => { target = t; },
-                None => return None
-            }
+            target = target.find(*key)?;
         }
         Some(target)
     }

src/libstd/collections/hash/set.rs

@@ -1152,16 +1152,12 @@ impl<'a, T, S> Iterator for Intersection<'a, T, S>
 
     fn next(&mut self) -> Option<&'a T> {
         loop {
-            match self.iter.next() {
-                None => return None,
-                Some(elt) => {
+            let elt = self.iter.next()?;
             if self.other.contains(elt) {
                 return Some(elt);
             }
         }
     }
-        }
-    }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
         let (_, upper) = self.iter.size_hint();
@@ -1202,16 +1198,12 @@ impl<'a, T, S> Iterator for Difference<'a, T, S>
 
     fn next(&mut self) -> Option<&'a T> {
         loop {
-            match self.iter.next() {
-                None => return None,
-                Some(elt) => {
+            let elt = self.iter.next()?;
             if !self.other.contains(elt) {
                 return Some(elt);
             }
         }
     }
-        }
-    }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
         let (_, upper) = self.iter.size_hint();

src/libstd/io/mod.rs

@@ -2019,10 +2019,9 @@ impl<R: Read> Iterator for Chars<R> {
     type Item = result::Result<char, CharsError>;
 
     fn next(&mut self) -> Option<result::Result<char, CharsError>> {
-        let first_byte = match read_one_byte(&mut self.inner) {
-            None => return None,
-            Some(Ok(b)) => b,
-            Some(Err(e)) => return Some(Err(CharsError::Other(e))),
+        let first_byte = match read_one_byte(&mut self.inner)? {
+            Ok(b) => b,
+            Err(e) => return Some(Err(CharsError::Other(e))),
         };
         let width = core_str::utf8_char_width(first_byte);
         if width == 1 { return Some(Ok(first_byte as char)) }

src/libstd/net/parser.rs

@@ -170,11 +170,7 @@ impl<'a> Parser<'a> {
                 return None;
             }
 
-            let octet = self.read_number(10, 3, 0x100).map(|n| n as u8);
-            match octet {
-                Some(d) => bs[i] = d,
-                None => return None,
-            };
+            bs[i] = self.read_number(10, 3, 0x100).map(|n| n as u8)?;
             i += 1;
         }
         Some(Ipv4Addr::new(bs[0], bs[1], bs[2], bs[3]))

src/libstd/sys/unix/thread.rs

@@ -255,10 +255,7 @@ pub mod guard {
 
     pub unsafe fn init() -> Option<usize> {
         let psize = os::page_size();
-        let mut stackaddr = match get_stack_start() {
-            Some(addr) => addr,
-            None => return None,
-        };
+        let mut stackaddr = get_stack_start()?;
 
         // Ensure stackaddr is page aligned! A parent process might
         // have reset RLIMIT_STACK to be non-page aligned. The

src/libstd/sys_common/net.rs

@@ -136,10 +136,7 @@ impl Iterator for LookupHost {
     fn next(&mut self) -> Option<SocketAddr> {
         loop {
             unsafe {
-                let cur = match self.cur.as_ref() {
-                    None => return None,
-                    Some(c) => c,
-                };
+                let cur = self.cur.as_ref()?;
                 self.cur = cur.ai_next;
                 match sockaddr_to_addr(mem::transmute(cur.ai_addr),
                                        cur.ai_addrlen as usize)

src/libstd/sys_common/wtf8.rs

@@ -578,10 +578,7 @@ impl Wtf8 {
     fn next_surrogate(&self, mut pos: usize) -> Option<(usize, u16)> {
         let mut iter = self.bytes[pos..].iter();
         loop {
-            let b = match iter.next() {
-                None => return None,
-                Some(&b) => b,
-            };
+            let b = *iter.next()?;
             if b < 0x80 {
                 pos += 1;
             } else if b < 0xE0 {

src/libstd_unicode/char.rs

@@ -1528,12 +1528,7 @@ impl<I: Iterator<Item = u16>> Iterator for DecodeUtf16<I> {
     fn next(&mut self) -> Option<Result<char, DecodeUtf16Error>> {
         let u = match self.buf.take() {
             Some(buf) => buf,
-            None => {
-                match self.iter.next() {
-                    Some(u) => u,
-                    None => return None,
-                }
-            }
+            None => self.iter.next()?
         };
 
         if u < 0xD800 || 0xDFFF < u {

src/libsyntax/attr.rs

@@ -1123,10 +1123,7 @@ impl MetaItem {
             _ => return None,
         };
         let list_closing_paren_pos = tokens.peek().map(|tt| tt.span().hi());
-        let node = match MetaItemKind::from_tokens(tokens) {
-            Some(node) => node,
-            _ => return None,
-        };
+        let node = MetaItemKind::from_tokens(tokens)?;
         let hi = match node {
             MetaItemKind::NameValue(ref lit) => lit.span.hi(),
             MetaItemKind::List(..) => list_closing_paren_pos.unwrap_or(span.hi()),
@@ -1182,10 +1179,8 @@ impl MetaItemKind {
         let mut tokens = delimited.into_trees().peekable();
         let mut result = Vec::new();
         while let Some(..) = tokens.peek() {
-            match NestedMetaItemKind::from_tokens(&mut tokens) {
-                Some(item) => result.push(respan(item.span(), item)),
-                None => return None,
-            }
+            let item = NestedMetaItemKind::from_tokens(&mut tokens)?;
+            result.push(respan(item.span(), item));
             match tokens.next() {
                 None | Some(TokenTree::Token(_, Token::Comma)) => {}
                 _ => return None,

src/libsyntax/parse/token.rs

@@ -620,10 +620,7 @@ fn prepend_attrs(sess: &ParseSess,
                  span: syntax_pos::Span)
     -> Option<tokenstream::TokenStream>
 {
-    let tokens = match tokens {
-        Some(tokens) => tokens,
-        None => return None,
-    };
+    let tokens = tokens?;
     if attrs.len() == 0 {
         return Some(tokens.clone())
     }

src/libsyntax_ext/format_foreign.rs

@@ -8,15 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-macro_rules! try_opt {
-    ($e:expr) => {
-        match $e {
-            Some(v) => v,
-            None => return None,
-        }
-    };
-}
-
 pub mod printf {
     use super::strcursor::StrCursor as Cur;
 
@@ -173,7 +164,7 @@ pub mod printf {
             s.push_str("{");
 
             if let Some(arg) = self.parameter {
-                try_opt!(write!(s, "{}", try_opt!(arg.checked_sub(1))).ok());
+                write!(s, "{}", arg.checked_sub(1)?).ok()?;
             }
 
             if has_options {
@@ -203,12 +194,12 @@ pub mod printf {
                 }
 
                 if let Some(width) = width {
-                    try_opt!(width.translate(&mut s).ok());
+                    width.translate(&mut s).ok()?;
                 }
 
                 if let Some(precision) = precision {
                     s.push_str(".");
-                    try_opt!(precision.translate(&mut s).ok());
+                    precision.translate(&mut s).ok()?;
                 }
 
                 if let Some(type_) = type_ {
@@ -277,13 +268,9 @@ pub mod printf {
     impl<'a> Iterator for Substitutions<'a> {
         type Item = Substitution<'a>;
         fn next(&mut self) -> Option<Self::Item> {
-            match parse_next_substitution(self.s) {
-                Some((sub, tail)) => {
+            let (sub, tail) = parse_next_substitution(self.s)?;
             self.s = tail;
             Some(sub)
-                },
-                None => None,
-            }
         }
     }
 
@@ -303,11 +290,10 @@ pub mod printf {
         use self::State::*;
 
         let at = {
-            let start = try_opt!(s.find('%'));
-            match s[start+1..].chars().next() {
-                Some('%') => return Some((Substitution::Escape, &s[start+2..])),
-                Some(_) => {/* fall-through */},
-                None => return None,
+            let start = s.find('%')?;
+            match s[start+1..].chars().next()? {
+                '%' => return Some((Substitution::Escape, &s[start+2..])),
+                _ => {/* fall-through */},
             }
 
             Cur::new_at_start(&s[start..])
@@ -335,16 +321,16 @@ pub mod printf {
         // Used to establish the full span at the end.
         let start = at;
         // The current position within the string.
-        let mut at = try_opt!(at.at_next_cp());
+        let mut at = at.at_next_cp()?;
         // `c` is the next codepoint, `next` is a cursor after it.
-        let (mut c, mut next) = try_opt!(at.next_cp());
+        let (mut c, mut next) = at.next_cp()?;
 
         // Update `at`, `c`, and `next`, exiting if we're out of input.
         macro_rules! move_to {
             ($cur:expr) => {
                 {
                     at = $cur;
-                    let (c_, next_) = try_opt!(at.next_cp());
+                    let (c_, next_) = at.next_cp()?;
                     c = c_;
                     next = next_;
                 }
@@ -801,32 +787,28 @@ pub mod shell {
     /// Parse the next substitution from the input string.
     pub fn parse_next_substitution(s: &str) -> Option<(Substitution, &str)> {
         let at = {
-            let start = try_opt!(s.find('$'));
-            match s[start+1..].chars().next() {
-                Some('$') => return Some((Substitution::Escape, &s[start+2..])),
-                Some(c @ '0' ... '9') => {
+            let start = s.find('$')?;
+            match s[start+1..].chars().next()? {
+                '$' => return Some((Substitution::Escape, &s[start+2..])),
+                c @ '0' ... '9' => {
                     let n = (c as u8) - b'0';
                     return Some((Substitution::Ordinal(n), &s[start+2..]));
                 },
-                Some(_) => {/* fall-through */},
-                None => return None,
+                _ => {/* fall-through */},
             }
 
             Cur::new_at_start(&s[start..])
         };
 
-        let at = try_opt!(at.at_next_cp());
-        match at.next_cp() {
-            Some((c, inner)) => {
+        let at = at.at_next_cp()?;
+        let (c, inner) = at.next_cp()?;
+
         if !is_ident_head(c) {
             None
         } else {
             let end = at_next_cp_while(inner, is_ident_tail);
             Some((Substitution::Name(at.slice_between(end).unwrap()), end.slice_after()))
         }
-            },
-            _ => None
-        }
     }
 
     fn at_next_cp_while<F>(mut cur: Cur, mut pred: F) -> Cur
@@ -946,10 +928,7 @@ mod strcursor {
         }
 
         pub fn next_cp(mut self) -> Option<(char, StrCursor<'a>)> {
-            let cp = match self.cp_after() {
-                Some(cp) => cp,
-                None => return None,
-            };
+            let cp = self.cp_after()?;
             self.seek_right(cp.len_utf8());
             Some((cp, self))
         }

src/libterm/terminfo/searcher.rs

@@ -20,10 +20,7 @@ use std::path::PathBuf;
 #[allow(deprecated)]
 pub fn get_dbpath_for_term(term: &str) -> Option<PathBuf> {
     let mut dirs_to_search = Vec::new();
-    let first_char = match term.chars().next() {
-        Some(c) => c,
-        None => return None,
-    };
+    let first_char = term.chars().next()?;
 
     // Find search directory
     if let Some(dir) = env::var_os("TERMINFO") {