From 92a5207cdac7259d3770e075bc2962fc8c0e7290 Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Wed, 16 Aug 2017 01:18:01 +0200
Subject: [PATCH 1/9] fix splat error with soak properties or expressions

---
 lib/coffeescript/nodes.js | 26 ++++++++++++++++++++++++--
 src/nodes.coffee          | 20 +++++++++++++++++++-
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index 1d5609bd96..bc95b50eeb 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -1702,7 +1702,7 @@
         if (content) {
           fragments.push(this.makeCode('>'));
           fragments.push(...content.compileNode(o, LEVEL_LIST));
-          fragments.push(...[this.makeCode('</'), ...tag, this.makeCode('>')]);
+          fragments.push(...([this.makeCode('</'), ...tag, this.makeCode('>')]));
         } else {
           fragments.push(this.makeCode(' />'));
         }
@@ -4207,7 +4207,29 @@
       }
 
       compileToFragments(o) {
-        return [this.makeCode('...'), ...this.name.compileToFragments(o)];
+        var fragment, fragments, ix, j, len1;
+        // Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
+        // and ensure correct compilation by wrapping the @name in `Parens`.
+        // Examples:
+        // [a?.b...]    => [(a?.b)...]
+        // f(a.b?.c...) => f((a.b?.c)...)
+        // [a if b...]  => [(a if b)...]
+        if (!(this.name instanceof Value) || (!(this.name.base instanceof Parens) && !this.isAssignable())) {
+          this.name = new Value(new Parens(this.name));
+          fragments = this.name.compileToFragments(o);
+          // We need to replace `void 0` with `[]` in compiled fragments.
+          // Example: [a?.b...]
+          // [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+          for (ix = j = 0, len1 = fragments.length; j < len1; ix = ++j) {
+            fragment = fragments[ix];
+            if (fragment.code === "void 0" && fragment.type === "If") {
+              fragments[ix].code = "[]";
+            }
+          }
+        } else {
+          fragments = this.name.compileToFragments(o);
+        }
+        return [this.makeCode('...'), ...fragments];
       }
 
       unwrap() {
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 677d4df028..be197baf24 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -2873,8 +2873,26 @@ exports.Splat = class Splat extends Base
     @name.assigns name
 
   compileToFragments: (o) ->
+    # Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
+    # and ensure correct compilation by wrapping the @name in `Parens`.
+    # Examples:
+    # [a?.b...]    => [(a?.b)...]
+    # f(a.b?.c...) => f((a.b?.c)...)
+    # [a if b...]  => [(a if b)...]
+    if not (@name instanceof Value) or
+        (not (@name.base instanceof Parens) and not @isAssignable())
+      @name = new Value new Parens @name
+      fragments = @name.compileToFragments o
+      # We need to replace `void 0` with `[]` in compiled fragments.
+      # Example: [a?.b...]
+      # [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+      for fragment, ix in fragments
+        fragments[ix].code = "[]" if fragment.code == "void 0" and fragment.type == "If"
+    else
+      fragments = @name.compileToFragments o
+
     [ @makeCode('...')
-      @name.compileToFragments(o)... ]
+      fragments... ]
 
   unwrap: -> @name
 

From aed529ffd18fadf3976032e49547af204a810cac Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webmaster@geoffreybooth.com>
Date: Tue, 22 Aug 2017 20:23:06 -0700
Subject: [PATCH 2/9] Add test based on #4260

---
 test/arrays.coffee | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/test/arrays.coffee b/test/arrays.coffee
index 5c509b28d9..29d5ba9a0d 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -38,7 +38,6 @@ test "array splat expansions with assignments", ->
 
 
 test "mixed shorthand objects in array lists", ->
-
   arr = [
     a:1
     'b'
@@ -58,7 +57,6 @@ test "mixed shorthand objects in array lists", ->
   eq arr[2].b, 1
   eq arr[3], 'b'
 
-
 test "array splats with nested arrays", ->
   nonce = {}
   a = [nonce]
@@ -70,6 +68,11 @@ test "array splats with nested arrays", ->
   list = [1, 2, a...]
   arrayEq list, [1, 2, [nonce]]
 
+test "#4260: splat after existential operator soak", ->
+  a = {b: [3]}
+  arrayEq [a?.b...], [3]
+  arrayEq [c?.b...], []
+
 test "#1274: `[] = a()` compiles to `false` instead of `a()`", ->
   a = false
   fn = -> a = true

From 5d08948653b1d643663a50f3f8f7744ee4adc2fc Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webmaster@geoffreybooth.com>
Date: Tue, 22 Aug 2017 20:29:03 -0700
Subject: [PATCH 3/9] Add test based on #1349

---
 test/arrays.coffee | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/test/arrays.coffee b/test/arrays.coffee
index 29d5ba9a0d..fa8be7c1ab 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -73,6 +73,13 @@ test "#4260: splat after existential operator soak", ->
   arrayEq [a?.b...], [3]
   arrayEq [c?.b...], []
 
+test "#1349: trailing if after splat", ->
+  a = [3]
+  b = yes
+  c = null
+  arrayEq [a if b...], [3]
+  arrayEq [a if c...], []
+
 test "#1274: `[] = a()` compiles to `false` instead of `a()`", ->
   a = false
   fn = -> a = true

From ba50f9ea934fca9a99b61a08b3917b70d7d8be6f Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Wed, 23 Aug 2017 13:26:49 +0200
Subject: [PATCH 4/9] tests for the leading splat variant

---
 test/arrays.coffee | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/test/arrays.coffee b/test/arrays.coffee
index fa8be7c1ab..f4a9510e21 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -72,6 +72,12 @@ test "#4260: splat after existential operator soak", ->
   a = {b: [3]}
   arrayEq [a?.b...], [3]
   arrayEq [c?.b...], []
+  arrayEq [...a?.b], [3]
+  arrayEq [...c?.b], []
+
+  # Should not trigger implicit call, e.g. rest ... => rest(...)
+  arrayEq [a?.b ...], [3]
+  arrayEq [c?.b ...], []
 
 test "#1349: trailing if after splat", ->
   a = [3]
@@ -79,6 +85,12 @@ test "#1349: trailing if after splat", ->
   c = null
   arrayEq [a if b...], [3]
   arrayEq [a if c...], []
+  arrayEq [...a if b], [3]
+  arrayEq [...a if c], []
+
+  # Should not trigger implicit call, e.g. rest ... => rest(...)
+  arrayEq [a if b ...], [3]
+  arrayEq [a if c ...], []
 
 test "#1274: `[] = a()` compiles to `false` instead of `a()`", ->
   a = false

From 47444bf54d19a1ed677f15b3704799999874c767 Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Thu, 24 Aug 2017 12:42:19 +0200
Subject: [PATCH 5/9] test for spaced prefix ...

---
 test/arrays.coffee | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/test/arrays.coffee b/test/arrays.coffee
index f4a9510e21..bea31ada99 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -76,6 +76,8 @@ test "#4260: splat after existential operator soak", ->
   arrayEq [...c?.b], []
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
+  arrayEq [... a?.b], [3]
+  arrayEq [... c?.b], []
   arrayEq [a?.b ...], [3]
   arrayEq [c?.b ...], []
 
@@ -89,6 +91,8 @@ test "#1349: trailing if after splat", ->
   arrayEq [...a if c], []
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
+  arrayEq [... a if b], [3]
+  arrayEq [... a if c], []
   arrayEq [a if b ...], [3]
   arrayEq [a if c ...], []
 

From 777a91666b88e2e21ef0de87678c3a84a4232b02 Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Thu, 24 Aug 2017 13:30:31 +0200
Subject: [PATCH 6/9] fixed 'if' statement in parens

---
 lib/coffeescript/nodes.js |  2 +-
 src/nodes.coffee          |  3 +--
 test/arrays.coffee        | 11 +++++++++++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index bc95b50eeb..6f58fabc8a 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -4214,7 +4214,7 @@
         // [a?.b...]    => [(a?.b)...]
         // f(a.b?.c...) => f((a.b?.c)...)
         // [a if b...]  => [(a if b)...]
-        if (!(this.name instanceof Value) || (!(this.name.base instanceof Parens) && !this.isAssignable())) {
+        if (!(this.name instanceof Value) || !this.isAssignable()) {
           this.name = new Value(new Parens(this.name));
           fragments = this.name.compileToFragments(o);
           // We need to replace `void 0` with `[]` in compiled fragments.
diff --git a/src/nodes.coffee b/src/nodes.coffee
index be197baf24..bea3173540 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -2879,8 +2879,7 @@ exports.Splat = class Splat extends Base
     # [a?.b...]    => [(a?.b)...]
     # f(a.b?.c...) => f((a.b?.c)...)
     # [a if b...]  => [(a if b)...]
-    if not (@name instanceof Value) or
-        (not (@name.base instanceof Parens) and not @isAssignable())
+    if not (@name instanceof Value) or not @isAssignable()
       @name = new Value new Parens @name
       fragments = @name.compileToFragments o
       # We need to replace `void 0` with `[]` in compiled fragments.
diff --git a/test/arrays.coffee b/test/arrays.coffee
index bea31ada99..e91055d599 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -74,12 +74,23 @@ test "#4260: splat after existential operator soak", ->
   arrayEq [c?.b...], []
   arrayEq [...a?.b], [3]
   arrayEq [...c?.b], []
+  e = yes
+  f = null
+  arrayEq [(a if e)?.b...], [3]
+  arrayEq [(a if f)?.b...], []
+  arrayEq [...(a if e)?.b], [3]
+  arrayEq [...(a if f)?.b], []
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
   arrayEq [... a?.b], [3]
   arrayEq [... c?.b], []
   arrayEq [a?.b ...], [3]
   arrayEq [c?.b ...], []
+  arrayEq [(a if e)?.b ...], [3]
+  arrayEq [(a if f)?.b ...], []
+  arrayEq [... (a if e)?.b], [3]
+  arrayEq [... (a if f)?.b], []
+
 
 test "#1349: trailing if after splat", ->
   a = [3]

From 81947d1c420adbbd16c9f27b248501edfd3d3450 Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Sat, 26 Aug 2017 11:00:16 +0200
Subject: [PATCH 7/9] fixed replacing 'void 0' with '[]'

---
 lib/coffeescript/nodes.js | 29 ++++++++++++++------------
 src/nodes.coffee          | 14 ++++++++-----
 test/arrays.coffee        | 43 ++++++++++++++++++++++++++++++++++++++-
 3 files changed, 67 insertions(+), 19 deletions(-)

diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index 6f58fabc8a..5c71d932a8 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -1406,7 +1406,7 @@
         }
         for (j = 0, len1 = props.length; j < len1; j++) {
           prop = props[j];
-          fragments.push(...prop.compileToFragments(o));
+          fragments.push(...(prop.compileToFragments(o)));
         }
         return fragments;
       }
@@ -1659,7 +1659,7 @@
           if (argIndex) {
             compiledArgs.push(this.makeCode(", "));
           }
-          compiledArgs.push(...arg.compileToFragments(o, LEVEL_LIST));
+          compiledArgs.push(...(arg.compileToFragments(o, LEVEL_LIST)));
         }
         fragments = [];
         if (this.isNew) {
@@ -1702,7 +1702,7 @@
         if (content) {
           fragments.push(this.makeCode('>'));
           fragments.push(...content.compileNode(o, LEVEL_LIST));
-          fragments.push(...([this.makeCode('</'), ...tag, this.makeCode('>')]));
+          fragments.push(...[this.makeCode('</'), ...tag, this.makeCode('>')]);
         } else {
           fragments.push(this.makeCode(' />'));
         }
@@ -3854,7 +3854,7 @@
           // Create a destructured assignment, e.g. `[a, b, c] = [args..., b, c]`
           exprs.unshift(new Assign(new Value(new Arr([
             new Splat(new IdentifierLiteral(splatParamName)),
-            ...(function() {
+            ...((function() {
               var k, len2, results;
               results = [];
               for (k = 0, len2 = paramsAfterSplat.length; k < len2; k++) {
@@ -3862,7 +3862,7 @@
                 results.push(param.asReference(o));
               }
               return results;
-            })()
+            })())
           ])), new Value(new IdentifierLiteral(splatParamName))));
         }
         // Add new expressions to the function body
@@ -4207,7 +4207,7 @@
       }
 
       compileToFragments(o) {
-        var fragment, fragments, ix, j, len1;
+        var flen, fragment, fragments, ix, j, len1;
         // Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
         // and ensure correct compilation by wrapping the @name in `Parens`.
         // Examples:
@@ -4215,15 +4215,18 @@
         // f(a.b?.c...) => f((a.b?.c)...)
         // [a if b...]  => [(a if b)...]
         if (!(this.name instanceof Value) || !this.isAssignable()) {
-          this.name = new Value(new Parens(this.name));
-          fragments = this.name.compileToFragments(o);
+          fragments = this.name.compileToFragments(o, LEVEL_OP);
           // We need to replace `void 0` with `[]` in compiled fragments.
-          // Example: [a?.b...]
-          // [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+          // Examples:
+          // - [a?.b...]
+          //   [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+          // - f(a?b...)
+          //   f(...(typeof c !== "undefined" && c !== null ? c.b : []))
+          flen = fragments.length;
           for (ix = j = 0, len1 = fragments.length; j < len1; ix = ++j) {
             fragment = fragments[ix];
-            if (fragment.code === "void 0" && fragment.type === "If") {
-              fragments[ix].code = "[]";
+            if (fragment.type === 'If' && fragment.code === 'void 0' && ix + 1 < flen && fragments[ix + 1].type !== 'Call') {
+              fragments[ix].code = '[]';
             }
           }
         } else {
@@ -5380,7 +5383,7 @@
           fragments.push(cond.makeCode(idt2 + 'break;\n'));
         }
         if (this.otherwise && this.otherwise.expressions.length) {
-          fragments.push(this.makeCode(idt1 + "default:\n"), ...this.otherwise.compileToFragments(o, LEVEL_TOP), this.makeCode("\n"));
+          fragments.push(this.makeCode(idt1 + "default:\n"), ...(this.otherwise.compileToFragments(o, LEVEL_TOP)), this.makeCode("\n"));
         }
         fragments.push(this.makeCode(this.tab + '}'));
         return fragments;
diff --git a/src/nodes.coffee b/src/nodes.coffee
index bea3173540..0728b0542c 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -2880,13 +2880,17 @@ exports.Splat = class Splat extends Base
     # f(a.b?.c...) => f((a.b?.c)...)
     # [a if b...]  => [(a if b)...]
     if not (@name instanceof Value) or not @isAssignable()
-      @name = new Value new Parens @name
-      fragments = @name.compileToFragments o
+      fragments = @name.compileToFragments o, LEVEL_OP
       # We need to replace `void 0` with `[]` in compiled fragments.
-      # Example: [a?.b...]
-      # [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+      # Examples:
+      # - [a?.b...]
+      #   [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
+      # - f(a?b...)
+      #   f(...(typeof c !== "undefined" && c !== null ? c.b : []))
+      flen = fragments.length
       for fragment, ix in fragments
-        fragments[ix].code = "[]" if fragment.code == "void 0" and fragment.type == "If"
+        fragments[ix].code = '[]' if fragment.type is 'If' and fragment.code is 'void 0' and
+            ix + 1 < flen and fragments[ix + 1].type isnt 'Call'
     else
       fragments = @name.compileToFragments o
 
diff --git a/test/arrays.coffee b/test/arrays.coffee
index e91055d599..ca54d85818 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -70,16 +70,43 @@ test "array splats with nested arrays", ->
 
 test "#4260: splat after existential operator soak", ->
   a = {b: [3]}
+  foo = (a) -> [a] ? []
+
   arrayEq [a?.b...], [3]
   arrayEq [c?.b...], []
   arrayEq [...a?.b], [3]
   arrayEq [...c?.b], []
+  arrayEq foo(a?.b...), [3]
+  arrayEq foo(...a?.b), [3]
+  arrayEq [foo(a?.b)...], [a.b]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo(a?.b)], [a.b]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo(a?.b...)...], [3]
+  arrayEq [...foo(...a?.b)], [3]
+  arrayEq foo(c?.b...), [undefined]
+  arrayEq foo(...c?.b), [undefined]
+  arrayEq [foo(c?.b)...], [undefined]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo(c?.b)], [undefined]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo(c?.b...)...], [undefined]
+  arrayEq [...foo(...c?.b)], [undefined]
+
   e = yes
   f = null
   arrayEq [(a if e)?.b...], [3]
   arrayEq [(a if f)?.b...], []
   arrayEq [...(a if e)?.b], [3]
   arrayEq [...(a if f)?.b], []
+  arrayEq foo((a if e)?.b...), [3]
+  arrayEq foo(...(a if e)?.b), [3]
+  arrayEq [foo((a if e)?.b)...], [a.b]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo((a if e)?.b)], [a.b]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo((a if e)?.b...)...], [3]
+  arrayEq [...foo(...(a if e)?.b)], [3]
+  arrayEq foo((a if f)?.b...), [undefined]
+  arrayEq foo(...(a if f)?.b), [undefined]
+  arrayEq [foo((a if f)?.b)...], [undefined]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo((a if f)?.b)], [undefined]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo((a if f)?.b...)...], [undefined]
+  arrayEq [...foo(...(a if f)?.b)], [undefined]
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
   arrayEq [... a?.b], [3]
@@ -90,16 +117,30 @@ test "#4260: splat after existential operator soak", ->
   arrayEq [(a if f)?.b ...], []
   arrayEq [... (a if e)?.b], [3]
   arrayEq [... (a if f)?.b], []
-
+  arrayEq foo(a?.b ...), [3]
+  arrayEq foo(... a?.b), [3]
 
 test "#1349: trailing if after splat", ->
   a = [3]
   b = yes
   c = null
+  foo = (a) -> [a]
   arrayEq [a if b...], [3]
   arrayEq [a if c...], []
   arrayEq [...a if b], [3]
   arrayEq [...a if c], []
+  arrayEq foo((a if b)...), [3]
+  arrayEq foo(...(a if b)), [3]
+  arrayEq [foo((a if b))...], [a]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo((a if b))], [a]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo((a if b)...)...], [3]
+  arrayEq [...foo(...(a if b))], [3]
+  arrayEq foo((a if c)...), [undefined]
+  arrayEq foo(...(a if c)), [undefined]
+  arrayEq [foo((a if c))...], [[]]   # `void 0` should not be replaced with `[]`
+  arrayEq [...foo((a if c))], [[]]   # `void 0` should not be replaced with `[]`
+  arrayEq [foo((a if c)...)...], [undefined]
+  arrayEq [...foo(...(a if c))], [undefined]
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
   arrayEq [... a if b], [3]

From 2efeaff952eb16543c662e2a04b7ad2c7878c882 Mon Sep 17 00:00:00 2001
From: Zdenko Vujasinovic <zdenko@tozd.si>
Date: Sun, 27 Aug 2017 08:40:34 +0200
Subject: [PATCH 8/9] remove 'void 0' replacement; add Splat::compileNode

---
 lib/coffeescript/nodes.js | 39 +++++--------------------
 src/nodes.coffee          | 25 ++--------------
 test/arrays.coffee        | 60 +++++++++------------------------------
 3 files changed, 23 insertions(+), 101 deletions(-)

diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index 5c71d932a8..bdb9dee5aa 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -1406,7 +1406,7 @@
         }
         for (j = 0, len1 = props.length; j < len1; j++) {
           prop = props[j];
-          fragments.push(...(prop.compileToFragments(o)));
+          fragments.push(...prop.compileToFragments(o));
         }
         return fragments;
       }
@@ -1659,7 +1659,7 @@
           if (argIndex) {
             compiledArgs.push(this.makeCode(", "));
           }
-          compiledArgs.push(...(arg.compileToFragments(o, LEVEL_LIST)));
+          compiledArgs.push(...arg.compileToFragments(o, LEVEL_LIST));
         }
         fragments = [];
         if (this.isNew) {
@@ -3854,7 +3854,7 @@
           // Create a destructured assignment, e.g. `[a, b, c] = [args..., b, c]`
           exprs.unshift(new Assign(new Value(new Arr([
             new Splat(new IdentifierLiteral(splatParamName)),
-            ...((function() {
+            ...(function() {
               var k, len2, results;
               results = [];
               for (k = 0, len2 = paramsAfterSplat.length; k < len2; k++) {
@@ -3862,7 +3862,7 @@
                 results.push(param.asReference(o));
               }
               return results;
-            })())
+            })()
           ])), new Value(new IdentifierLiteral(splatParamName))));
         }
         // Add new expressions to the function body
@@ -4206,33 +4206,8 @@
         return this.name.assigns(name);
       }
 
-      compileToFragments(o) {
-        var flen, fragment, fragments, ix, j, len1;
-        // Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
-        // and ensure correct compilation by wrapping the @name in `Parens`.
-        // Examples:
-        // [a?.b...]    => [(a?.b)...]
-        // f(a.b?.c...) => f((a.b?.c)...)
-        // [a if b...]  => [(a if b)...]
-        if (!(this.name instanceof Value) || !this.isAssignable()) {
-          fragments = this.name.compileToFragments(o, LEVEL_OP);
-          // We need to replace `void 0` with `[]` in compiled fragments.
-          // Examples:
-          // - [a?.b...]
-          //   [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
-          // - f(a?b...)
-          //   f(...(typeof c !== "undefined" && c !== null ? c.b : []))
-          flen = fragments.length;
-          for (ix = j = 0, len1 = fragments.length; j < len1; ix = ++j) {
-            fragment = fragments[ix];
-            if (fragment.type === 'If' && fragment.code === 'void 0' && ix + 1 < flen && fragments[ix + 1].type !== 'Call') {
-              fragments[ix].code = '[]';
-            }
-          }
-        } else {
-          fragments = this.name.compileToFragments(o);
-        }
-        return [this.makeCode('...'), ...fragments];
+      compileNode(o) {
+        return [this.makeCode('...'), ...this.name.compileToFragments(o)];
       }
 
       unwrap() {
@@ -5383,7 +5358,7 @@
           fragments.push(cond.makeCode(idt2 + 'break;\n'));
         }
         if (this.otherwise && this.otherwise.expressions.length) {
-          fragments.push(this.makeCode(idt1 + "default:\n"), ...(this.otherwise.compileToFragments(o, LEVEL_TOP)), this.makeCode("\n"));
+          fragments.push(this.makeCode(idt1 + "default:\n"), ...this.otherwise.compileToFragments(o, LEVEL_TOP), this.makeCode("\n"));
         }
         fragments.push(this.makeCode(this.tab + '}'));
         return fragments;
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 0728b0542c..949892985d 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -2872,30 +2872,9 @@ exports.Splat = class Splat extends Base
   assigns: (name) ->
     @name.assigns name
 
-  compileToFragments: (o) ->
-    # Check if @name is not an instance of `Value` or @name properties contains soak accessor, e.g. ?.b,
-    # and ensure correct compilation by wrapping the @name in `Parens`.
-    # Examples:
-    # [a?.b...]    => [(a?.b)...]
-    # f(a.b?.c...) => f((a.b?.c)...)
-    # [a if b...]  => [(a if b)...]
-    if not (@name instanceof Value) or not @isAssignable()
-      fragments = @name.compileToFragments o, LEVEL_OP
-      # We need to replace `void 0` with `[]` in compiled fragments.
-      # Examples:
-      # - [a?.b...]
-      #   [...(a !== null ? a.b : void 0)] => [...(a !== null ? a.b : [])]
-      # - f(a?b...)
-      #   f(...(typeof c !== "undefined" && c !== null ? c.b : []))
-      flen = fragments.length
-      for fragment, ix in fragments
-        fragments[ix].code = '[]' if fragment.type is 'If' and fragment.code is 'void 0' and
-            ix + 1 < flen and fragments[ix + 1].type isnt 'Call'
-    else
-      fragments = @name.compileToFragments o
-
+  compileNode: (o) ->
     [ @makeCode('...')
-      fragments... ]
+      @name.compileToFragments(o)... ]
 
   unwrap: -> @name
 
diff --git a/test/arrays.coffee b/test/arrays.coffee
index ca54d85818..0963d3e591 100644
--- a/test/arrays.coffee
+++ b/test/arrays.coffee
@@ -70,53 +70,31 @@ test "array splats with nested arrays", ->
 
 test "#4260: splat after existential operator soak", ->
   a = {b: [3]}
-  foo = (a) -> [a] ? []
-
+  foo = (a) -> [a]
   arrayEq [a?.b...], [3]
-  arrayEq [c?.b...], []
+  arrayEq [c?.b ? []...], []
   arrayEq [...a?.b], [3]
-  arrayEq [...c?.b], []
+  arrayEq [...c?.b ? []], []
   arrayEq foo(a?.b...), [3]
   arrayEq foo(...a?.b), [3]
-  arrayEq [foo(a?.b)...], [a.b]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo(a?.b)], [a.b]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo(a?.b...)...], [3]
-  arrayEq [...foo(...a?.b)], [3]
-  arrayEq foo(c?.b...), [undefined]
-  arrayEq foo(...c?.b), [undefined]
-  arrayEq [foo(c?.b)...], [undefined]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo(c?.b)], [undefined]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo(c?.b...)...], [undefined]
-  arrayEq [...foo(...c?.b)], [undefined]
-
+  arrayEq foo(c?.b ? []...), [undefined]
+  arrayEq foo(...c?.b ? []), [undefined]
   e = yes
   f = null
   arrayEq [(a if e)?.b...], [3]
-  arrayEq [(a if f)?.b...], []
+  arrayEq [(a if f)?.b ? []...], []
   arrayEq [...(a if e)?.b], [3]
-  arrayEq [...(a if f)?.b], []
+  arrayEq [...(a if f)?.b ? []], []
   arrayEq foo((a if e)?.b...), [3]
   arrayEq foo(...(a if e)?.b), [3]
-  arrayEq [foo((a if e)?.b)...], [a.b]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo((a if e)?.b)], [a.b]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo((a if e)?.b...)...], [3]
-  arrayEq [...foo(...(a if e)?.b)], [3]
-  arrayEq foo((a if f)?.b...), [undefined]
-  arrayEq foo(...(a if f)?.b), [undefined]
-  arrayEq [foo((a if f)?.b)...], [undefined]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo((a if f)?.b)], [undefined]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo((a if f)?.b...)...], [undefined]
-  arrayEq [...foo(...(a if f)?.b)], [undefined]
+  arrayEq foo((a if f)?.b ? []...), [undefined]
+  arrayEq foo(...(a if f)?.b ? []), [undefined]
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
   arrayEq [... a?.b], [3]
-  arrayEq [... c?.b], []
+  arrayEq [... c?.b ? []], []
   arrayEq [a?.b ...], [3]
-  arrayEq [c?.b ...], []
   arrayEq [(a if e)?.b ...], [3]
-  arrayEq [(a if f)?.b ...], []
-  arrayEq [... (a if e)?.b], [3]
-  arrayEq [... (a if f)?.b], []
   arrayEq foo(a?.b ...), [3]
   arrayEq foo(... a?.b), [3]
 
@@ -126,27 +104,17 @@ test "#1349: trailing if after splat", ->
   c = null
   foo = (a) -> [a]
   arrayEq [a if b...], [3]
-  arrayEq [a if c...], []
+  arrayEq [(a if c) ? []...], []
   arrayEq [...a if b], [3]
-  arrayEq [...a if c], []
+  arrayEq [...(a if c) ? []], []
   arrayEq foo((a if b)...), [3]
   arrayEq foo(...(a if b)), [3]
-  arrayEq [foo((a if b))...], [a]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo((a if b))], [a]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo((a if b)...)...], [3]
-  arrayEq [...foo(...(a if b))], [3]
-  arrayEq foo((a if c)...), [undefined]
-  arrayEq foo(...(a if c)), [undefined]
-  arrayEq [foo((a if c))...], [[]]   # `void 0` should not be replaced with `[]`
-  arrayEq [...foo((a if c))], [[]]   # `void 0` should not be replaced with `[]`
-  arrayEq [foo((a if c)...)...], [undefined]
-  arrayEq [...foo(...(a if c))], [undefined]
+  arrayEq foo((a if c) ? []...), [undefined]
+  arrayEq foo(...(a if c) ? []), [undefined]
 
   # Should not trigger implicit call, e.g. rest ... => rest(...)
   arrayEq [... a if b], [3]
-  arrayEq [... a if c], []
   arrayEq [a if b ...], [3]
-  arrayEq [a if c ...], []
 
 test "#1274: `[] = a()` compiles to `false` instead of `a()`", ->
   a = false

From 9863aae99799af2ba30d3d75c36514d509cd2128 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webmaster@geoffreybooth.com>
Date: Sat, 26 Aug 2017 23:56:25 -0700
Subject: [PATCH 9/9] Use LEVEL_OP; follow style better

---
 lib/coffeescript/nodes.js | 10 +++++-----
 src/nodes.coffee          | 10 ++++------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index bdb9dee5aa..44da97411a 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -4193,21 +4193,21 @@
   // or as part of a destructuring assignment.
   exports.Splat = Splat = (function() {
     class Splat extends Base {
-      isAssignable() {
-        return this.name.isAssignable() && (!this.name.isAtomic || this.name.isAtomic());
-      }
-
       constructor(name) {
         super();
         this.name = name.compile ? name : new Literal(name);
       }
 
+      isAssignable() {
+        return this.name.isAssignable() && (!this.name.isAtomic || this.name.isAtomic());
+      }
+
       assigns(name) {
         return this.name.assigns(name);
       }
 
       compileNode(o) {
-        return [this.makeCode('...'), ...this.name.compileToFragments(o)];
+        return [this.makeCode('...'), ...this.name.compileToFragments(o, LEVEL_OP)];
       }
 
       unwrap() {
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 949892985d..1edeeb3b8a 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -2859,22 +2859,20 @@ exports.Param = class Param extends Base
 # A splat, either as a parameter to a function, an argument to a call,
 # or as part of a destructuring assignment.
 exports.Splat = class Splat extends Base
+  constructor: (name) ->
+    super()
+    @name = if name.compile then name else new Literal name
 
   children: ['name']
 
   isAssignable: ->
     @name.isAssignable() and (not @name.isAtomic or @name.isAtomic())
 
-  constructor: (name) ->
-    super()
-    @name = if name.compile then name else new Literal name
-
   assigns: (name) ->
     @name.assigns name
 
   compileNode: (o) ->
-    [ @makeCode('...')
-      @name.compileToFragments(o)... ]
+    [@makeCode('...'), @name.compileToFragments(o, LEVEL_OP)...]
 
   unwrap: -> @name