Rollup merge of #54409 - estebank:remove-in, r=pnkfelix

Detect `for _ in in bar {}` typo

Fix #36611, #52964, without modifying the parsing of emplacement `in` to avoid further problems like #50832.

src/test/ui/did_you_mean/issue-54109-and_instead_of_ampersands.stderr

@@ -2,16 +2,20 @@ error: expected `{`, found `and`
   --> $DIR/issue-54109-and_instead_of_ampersands.rs:14:10
    |
 LL |     if a and b {
-   |     --   ^^^ help: use `&&` instead of `and` for the boolean operator
-   |     |
+   |     --   ^^^
+   |     |    |
+   |     |    expected `{`
+   |     |    help: use `&&` instead of `and` for the boolean operator
    |     this `if` statement has a condition, but no block
 
 error: expected `{`, found `or`
   --> $DIR/issue-54109-and_instead_of_ampersands.rs:23:10
    |
 LL |     if a or b {
-   |     --   ^^ help: use `||` instead of `or` for the boolean operator
-   |     |
+   |     --   ^^
+   |     |    |
+   |     |    expected `{`
+   |     |    help: use `||` instead of `or` for the boolean operator
    |     this `if` statement has a condition, but no block
 
 error: expected one of `!`, `)`, `,`, `.`, `::`, `?`, `{`, or an operator, found `and`

src/test/ui/parser/if-in-in.rs

@@ -0,0 +1,5 @@
+fn main() {
+    for i in in 1..2 {
+        println!("{}", i);
+    }
+}

src/test/ui/parser/if-in-in.stderr

@@ -0,0 +1,13 @@
+error: expected iterable, found keyword `in`
+  --> $DIR/if-in-in.rs:2:14
+   |
+LL |     for i in in 1..2 {
+   |           ---^^
+   |           |
+   |           help: remove the duplicated `in`
+   |
+   = note: if you meant to use emplacement syntax, it is obsolete (for now, anyway)
+   = note: for more information on the status of emplacement syntax, see <https://github.com/rust-lang/rust/issues/27779#issuecomment-378416911>
+
+error: aborting due to previous error
+