From e1dcc490d2ece65e130181d78c2c813a066d23b1 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sat, 27 Nov 2021 14:25:17 -0800
Subject: [PATCH] Pattern parser to preserve all spans in `if let` and `for`

---
 src/ensure.rs | 104 ++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 89 insertions(+), 15 deletions(-)

diff --git a/src/ensure.rs b/src/ensure.rs
index 868feb3..dcb9b09 100644
--- a/src/ensure.rs
+++ b/src/ensure.rs
@@ -143,8 +143,8 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!(0 $stack $bail ($($fuel)*) {($($buf)* $neg) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($let:tt $($dup:tt)*) let $(|)? $($pat:pat)|+ = $($rest:tt)*) => {
-        $crate::__parse_ensure!(0 $stack $bail ($($fuel)*) {($($buf)* $let $($pat)|+ =) $($parse)*} ($($rest)*) $($rest)*)
+    (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($let:tt $($dup:tt)*) let $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $let) $($parse)*} ($($rest)*) $($rest)*)
     };
 
     (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($life:tt $colon:tt $($dup:tt)*) $label:lifetime : $($rest:tt)*) => {
@@ -181,8 +181,8 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!(0 (cond $stack) $bail ($($fuel)*) {($($buf)* $while) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($for:tt $($dup:tt)*) for $(|)? $($pat:pat)|+ in $($rest:tt)*) => {
-        $crate::__parse_ensure!(0 (cond $stack) $bail ($($fuel)*) {($($buf)* $for $($pat)|+ in) $($parse)*} ($($rest)*) $($rest)*)
+    (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($for:tt $($dup:tt)*) for $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat (cond $stack) $bail ($($fuel)*) {($($buf)* $for) $($parse)*} ($($rest)*) $($rest)*)
     };
 
     (atom (cond $stack:tt) $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($brace:tt $($dup:tt)*) {$($block:tt)*} $($rest:tt)*) => {
@@ -238,15 +238,15 @@ macro_rules! __parse_ensure {
     // path expressions
 
     (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($colons:tt $($dup:tt)*) :: $ident:ident $($rest:tt)*) => {
-        $crate::__parse_ensure!(epath $stack $bail ($($fuel)*) {($($buf)* $colons $ident) $($parse)*} ($($rest)*) $($rest)*)
+        $crate::__parse_ensure!(epath (atom $stack) $bail ($($fuel)*) {($($buf)* $colons $ident) $($parse)*} ($($rest)*) $($rest)*)
     };
 
     (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} $dup:tt $ident:ident $($rest:tt)*) => {
-        $crate::__parse_ensure!(epath $stack $bail ($($fuel)*) {($($buf)* $ident) $($parse)*} ($($rest)*) $($rest)*)
+        $crate::__parse_ensure!(epath (atom $stack) $bail ($($fuel)*) {($($buf)* $ident) $($parse)*} ($($rest)*) $($rest)*)
     };
 
     (0 $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($langle:tt $($dup:tt)*) < $($rest:tt)*) => {
-        $crate::__parse_ensure!(type (qpath (epath $stack)) $bail ($($fuel)*) {($($buf)* $langle) $($parse)*} ($($rest)*) $($rest)*)
+        $crate::__parse_ensure!(type (qpath (epath (atom $stack))) $bail ($($fuel)*) {($($buf)* $langle) $($parse)*} ($($rest)*) $($rest)*)
     };
 
     (epath $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($colons:tt $langle:tt $($dup:tt)*) :: < $($rest:tt)*) => {
@@ -261,20 +261,20 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!(epath $stack $bail ($($fuel)*) {($($buf)* $colons $ident) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (epath $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! ($($mac:tt)*) $($rest:tt)*) => {
-        $crate::__parse_ensure!(atom $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
+    (epath ($pop:ident $stack:tt) $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! ($($mac:tt)*) $($rest:tt)*) => {
+        $crate::__parse_ensure!($pop $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (epath $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! [$($mac:tt)*] $($rest:tt)*) => {
-        $crate::__parse_ensure!(atom $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
+    (epath ($pop:ident $stack:tt) $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! [$($mac:tt)*] $($rest:tt)*) => {
+        $crate::__parse_ensure!($pop $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (epath $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! {$($mac:tt)*} $($rest:tt)*) => {
-        $crate::__parse_ensure!(atom $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
+    (epath ($pop:ident $stack:tt) $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bang:tt $args:tt $($dup:tt)*) ! {$($mac:tt)*} $($rest:tt)*) => {
+        $crate::__parse_ensure!($pop $stack $bail ($($fuel)*) {($($buf)* $bang $args) $($parse)*} ($($rest)*) $($rest)*)
     };
 
-    (epath $stack:tt $bail:tt (~$($fuel:tt)*) $parse:tt $dup:tt $($rest:tt)*) => {
-        $crate::__parse_ensure!(atom $stack $bail ($($fuel)*) $parse $dup $($rest)*)
+    (epath ($pop:ident $stack:tt) $bail:tt (~$($fuel:tt)*) $parse:tt $dup:tt $($rest:tt)*) => {
+        $crate::__parse_ensure!($pop $stack $bail ($($fuel)*) $parse $dup $($rest)*)
     };
 
     // trailer expressions
@@ -537,6 +537,80 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!($pop $stack $bail ($($fuel)*) {($($buf)* >) $($parse)*} (> $($rest)*) > $($rest)*)
     };
 
+    // patterns
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($pipe:tt $($dup:tt)*) | $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $pipe) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($eq:tt $($dup:tt)*) = $($rest:tt)*) => {
+        $crate::__parse_ensure!(0 $stack $bail ($($fuel)*) {($($buf)* $eq) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($in:tt $($dup:tt)*) in $($rest:tt)*) => {
+        $crate::__parse_ensure!(0 $stack $bail ($($fuel)*) {($($buf)* $in) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($ref:tt $($dup:tt)*) ref $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $ref) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($mut:tt $($dup:tt)*) mut $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $mut) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($at:tt $($dup:tt)*) @ $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $at) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} $dup:tt $lit:literal $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $lit) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($range:tt $($dup:tt)*) .. $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $range) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($range:tt $($dup:tt)*) ..= $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $range) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($and:tt $($dup:tt)*) & $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $and) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($andand:tt $($dup:tt)*) && $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $andand) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($paren:tt $($dup:tt)*) ($($content:tt)*) $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $paren) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($bracket:tt $($dup:tt)*) [$($content:tt)*] $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $bracket) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($brace:tt $($dup:tt)*) {$($content:tt)*} $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $brace) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($wild:tt $($dup:tt)*) _ $($rest:tt)*) => {
+        $crate::__parse_ensure!(pat $stack $bail ($($fuel)*) {($($buf)* $wild) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($colons:tt $($dup:tt)*) :: $ident:ident $($rest:tt)*) => {
+        $crate::__parse_ensure!(epath (pat $stack) $bail ($($fuel)*) {($($buf)* $colons $ident) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} $dup:tt $ident:ident $($rest:tt)*) => {
+        $crate::__parse_ensure!(epath (pat $stack) $bail ($($fuel)*) {($($buf)* $ident) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
+    (pat $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($langle:tt $($dup:tt)*) < $($rest:tt)*) => {
+        $crate::__parse_ensure!(type (qpath (epath (pat $stack))) $bail ($($fuel)*) {($($buf)* $langle) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
     // high precedence binary operators
 
     (atom $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($add:tt $($dup:tt)*) + $($rest:tt)*) => {