Hoist array binding and rest ref declarations. Fixes #1139. Fixes #1312

source/parser/lib.civet

@@ -877,6 +877,8 @@ function processAssignments(statements): void {
             lhs.children.splice(0, 0, "(")
             tail.push(")")
 
+      refsToDeclare := new Set<ASTRef>
+
       // Walk from right to left to handle splices
       i = len - 1
       while i >= 0
@@ -916,6 +918,9 @@ function processAssignments(statements): void {
               break
           else if lhs.type is like "ObjectBindingPattern", "ArrayBindingPattern"
             processBindingPatternLHS(lhs, tail)
+            // Extract temp refs that need to be declared from lhs
+            gatherRecursiveAll(lhs, .type is "Ref").forEach refsToDeclare@add
+
           // NOTE: currently not processing any non-binding pattern ObjectExpression or ArrayExpressions
           // This might not be correct in all situations, esp BindingPatterns nested inside ObjectExpressions
         i--
@@ -937,18 +942,27 @@ function processAssignments(statements): void {
 
           if newMemberExp !== lhs
             if newMemberExp.usesRef
-              exp.hoistDec = {
+              exp.hoistDec =
                 type: "Declaration"
                 children: ["let ", optionalChainRef]
                 names: []
-              }
 
             replaceNode $2, newMemberExp
             newMemberExp.parent = exp
             $2 = newMemberExp
 
         i--
 
+      // Add any additional binding refs that need to be declared to our hoisted declarations
+      if refsToDeclare.size
+        if exp.hoistDec
+          exp.hoistDec.children.push [...refsToDeclare].map [",", &]
+        else
+          exp.hoistDec =
+            type: "Declaration"
+            children: ["let ", [...refsToDeclare].map (r, i) => i ? [",", r] : r]
+            names: []
+
       // Gather all identifier names from the lhs array
       exp.names = $1.flatMap(([, l]) => l.names or [])
 

test/assignment.civet

@@ -111,6 +111,38 @@ describe "assignment", ->
     [a, ...b] = d, [c] = b.splice(-1)
   """
 
+  testCase """
+    array destructuring with anon rest element
+    ---
+    [a, ..., c] = d
+    ---
+    let ref;[a, ...ref] = d, [c] = ref.splice(-1)
+  """
+
+  testCase """
+    array destructure into @rest
+    ---
+    [, ...@rest] = c
+    ---
+    let rest;[, ...rest] = c, this.rest = rest
+  """
+
+  testCase """
+    destructure into @ bindings
+    ---
+    [@a, b] = c
+    ---
+    let a;[a, b] = c, this.a = a
+  """
+
+  testCase """
+    complex destructure
+    ---
+    {a: [@b, ..., @c], x: { y: [@a, @d, ..., @e] } } = x
+    ---
+    let b,ref,a1,d,ref1;({a: [b, ...ref], x: { y: [a1, d, ...ref1] } } = x), [c] = ref.splice(-1), [e] = ref1.splice(-1), this.b = b, this.c = c, this.a = a1, this.d = d, this.e = e
+  """
+
   testCase """
     object destructuring
     ---
@@ -219,23 +251,23 @@ describe "assignment", ->
     ---
     [a, ..., b] = d
     ---
-    [a, ...ref] = d, [b] = ref.splice(-1)
+    let ref;[a, ...ref] = d, [b] = ref.splice(-1)
   """
 
   testCase """
     non-end rest element with post rest trailing comma
     ---
     [a, ..., b,] = d
     ---
-    [a, ...ref] = d, [b,] = ref.splice(-2)
+    let ref;[a, ...ref] = d, [b,] = ref.splice(-2)
   """
 
   testCase """
     non-end rest element with post rest elisions
     ---
     [a, ..., b,,,] = d
     ---
-    [a, ...ref] = d, [b,,,] = ref.splice(-4)
+    let ref;[a, ...ref] = d, [b,,,] = ref.splice(-4)
   """
 
   testCase """
@@ -251,7 +283,7 @@ describe "assignment", ->
     ---
     { x, y: [b, ...@c, d] } = e
     ---
-    ({ x, y: [b, ...c] } = e), [d] = c.splice(-1), this.c = c
+    let c;({ x, y: [b, ...c] } = e), [d] = c.splice(-1), this.c = c
   """
 
   testCase """