Merge #306

306: Finish weird exprs r=DJMcNab a=DJMcNab

Fix #290.

Note that I'm not certain my use of `p.nth(1) == Ident` is entirely consistent with `libsyntax` - in the original, [`is_union_item`](9622f9dc47/src/libsyntax/parse/parser.rs (L4593-L4596)) uses `t.is_ident() && !t.is_reserved_ident()`, whereas we effectively only do `is_ident`. However, I cannot find the definition of `is_reserved_ident` (even searching the rust repository only gives uses, no definitions), so this will have to do unless someone else can find it :|.

Co-authored-by: DJMcNab <36049421+djmcnab@users.noreply.github.com>

crates/ra_syntax/src/grammar/items.rs

@@ -202,7 +202,7 @@ fn items_without_modifiers(p: &mut Parser) -> Option<SyntaxKind> {
             }
             STRUCT_DEF
         }
-        IDENT if p.at_contextual_kw("union") => {
+        IDENT if p.at_contextual_kw("union") && p.nth(1) == IDENT => {
             // test union_items
             // union Foo {}
             // union Foo {

crates/ra_syntax/tests/data/parser/ok/0035_weird_exprs.rs

@@ -0,0 +1,154 @@
+//! Adapted from a `rustc` test, which can be found at 
+//! https://github.com/rust-lang/rust/blob/6d34ec18c7d7e574553f6347ecf08e1e1c45c13d/src/test/run-pass/weird-exprs.rs.
+//! 
+//! Reported to rust-analyzer in https://github.com/rust-analyzer/rust-analyzer/issues/290
+
+#![allow(non_camel_case_types)]
+#![allow(dead_code)]
+#![allow(unreachable_code)]
+#![allow(unused_parens)]
+
+#![recursion_limit = "128"]
+
+use std::cell::Cell;
+use std::mem::swap;
+
+// Just a grab bag of stuff that you wouldn't want to actually write.
+
+fn strange() -> bool { let _x: bool = return true; }
+
+fn funny() {
+    fn f(_x: ()) { }
+    f(return);
+}
+
+fn what() {
+    fn the(x: &Cell<bool>) {
+        return while !x.get() { x.set(true); };
+    }
+    let i = &Cell::new(false);
+    let dont = {||the(i)};
+    dont();
+    assert!((i.get()));
+}
+
+fn zombiejesus() {
+    loop {
+        while (return) {
+            if (return) {
+                match (return) {
+                    1 => {
+                        if (return) {
+                            return
+                        } else {
+                            return
+                        }
+                    }
+                    _ => { return }
+                };
+            } else if (return) {
+                return;
+            }
+        }
+        if (return) { break; }
+    }
+}
+
+fn notsure() {
+    let mut _x: isize;
+    let mut _y = (_x = 0) == (_x = 0);
+    let mut _z = (_x = 0) < (_x = 0);
+    let _a = (_x += 0) == (_x = 0);
+    let _b = swap(&mut _y, &mut _z) == swap(&mut _y, &mut _z);
+}
+
+fn canttouchthis() -> usize {
+    fn p() -> bool { true }
+    let _a = (assert!((true)) == (assert!(p())));
+    let _c = (assert!((p())) == ());
+    let _b: bool = (println!("{}", 0) == (return 0));
+}
+
+fn angrydome() {
+    loop { if break { } }
+    let mut i = 0;
+    loop { i += 1; if i == 1 { match (continue) { 1 => { }, _ => panic!("wat") } }
+      break; }
+}
+
+fn evil_lincoln() { let _evil = println!("lincoln"); }
+
+fn dots() {
+    assert_eq!(String::from(".................................................."),
+               format!("{:?}", .. .. .. .. .. .. .. .. .. .. .. .. ..
+                               .. .. .. .. .. .. .. .. .. .. .. ..));
+}
+
+fn u8(u8: u8) {
+    if u8 != 0u8 {
+        assert_eq!(8u8, {
+            macro_rules! u8 {
+                (u8) => {
+                    mod u8 {
+                        pub fn u8<'u8: 'u8 + 'u8>(u8: &'u8 u8) -> &'u8 u8 {
+                            "u8";
+                            u8
+                        }
+                    }
+                };
+            }
+
+            u8!(u8);
+            let &u8: &u8 = u8::u8(&8u8);
+            crate::u8(0u8);
+            u8
+        });
+    }
+}
+
+fn fishy() {
+    assert_eq!(String::from("><>"),
+               String::<>::from::<>("><>").chars::<>().rev::<>().collect::<String>());
+}
+
+fn union() {
+    union union<'union> { union: &'union union<'union>, }
+}
+
+fn special_characters() {
+    let val = !((|(..):(_,_),__@_|__)((&*"\\",'🤔')/**/,{})=={&[..=..][..];})//
+    ;
+    assert!(!val);
+}
+
+fn punch_card() -> impl std::fmt::Debug {
+    ..=..=.. ..    .. .. .. ..    .. .. .. ..    .. ..=.. ..
+    ..=.. ..=..    .. .. .. ..    .. .. .. ..    ..=..=..=..
+    ..=.. ..=..    ..=.. ..=..    .. ..=..=..    .. ..=.. ..
+    ..=..=.. ..    ..=.. ..=..    ..=.. .. ..    .. ..=.. ..
+    ..=.. ..=..    ..=.. ..=..    .. ..=.. ..    .. ..=.. ..
+    ..=.. ..=..    ..=.. ..=..    .. .. ..=..    .. ..=.. ..
+    ..=.. ..=..    .. ..=..=..    ..=..=.. ..    .. ..=.. ..
+}
+
+fn ktulhu() {
+    ;;;();;;;;;;;;()
+}
+
+pub fn main() {
+    strange();
+    funny();
+    what();
+    zombiejesus();
+    notsure();
+    canttouchthis();
+    angrydome();
+    evil_lincoln();
+    dots();
+    u8(8u8);
+    fishy();
+    union();
+    special_characters();
+    punch_card();
+    ktulhu();
+}