From 859466f5dd8469ce6934797c741e9aba65b1b9a0 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk@outlook.com>
Date: Tue, 3 Nov 2020 10:48:36 +0200
Subject: [PATCH] feat(31388): allow binding elements starting with an
 underscore

---
 src/compiler/checker.ts                       |  15 +-
 ...sWithUnderscoreInBindingElement.errors.txt | 145 +++++++
 ...VariablesWithUnderscoreInBindingElement.js | 136 +++++++
 ...blesWithUnderscoreInBindingElement.symbols | 279 +++++++++++++
 ...iablesWithUnderscoreInBindingElement.types | 378 ++++++++++++++++++
 ...iablesWithUnderscoreInForOfLoop.errors.txt |  56 +++
 ...nusedVariablesWithUnderscoreInForOfLoop.js |  43 +-
 ...VariablesWithUnderscoreInForOfLoop.symbols |  37 +-
 ...edVariablesWithUnderscoreInForOfLoop.types |  67 +++-
 ...ablesWithUnderscoreInForOfLoop1.errors.txt |  23 --
 ...usedVariablesWithUnderscoreInForOfLoop1.js |  22 -
 ...ariablesWithUnderscoreInForOfLoop1.symbols |  17 -
 ...dVariablesWithUnderscoreInForOfLoop1.types |  29 --
 ...VariablesWithUnderscoreInBindingElement.ts |  90 +++++
 ...nusedVariablesWithUnderscoreInForOfLoop.ts |  21 +-
 ...usedVariablesWithUnderscoreInForOfLoop1.ts |   9 -
 16 files changed, 1253 insertions(+), 114 deletions(-)
 create mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.errors.txt
 create mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.js
 create mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.symbols
 create mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.types
 create mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.errors.txt
 delete mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.errors.txt
 delete mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.js
 delete mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.symbols
 delete mode 100644 tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.types
 create mode 100644 tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts
 delete mode 100644 tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a220e79dc44a5..a79e835e54ee2 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -33362,13 +33362,16 @@ namespace ts {
         }
 
         function isValidUnusedLocalDeclaration(declaration: Declaration): boolean {
-            if (isBindingElement(declaration) && isIdentifierThatStartsWithUnderscore(declaration.name)) {
-                return !!findAncestor(declaration.parent, ancestor =>
-                    isArrayBindingPattern(ancestor) || isVariableDeclaration(ancestor) || isVariableDeclarationList(ancestor) ? false :
-                        isForOfStatement(ancestor) ? true : "quit"
-                );
+            if (isBindingElement(declaration)) {
+                if (isObjectBindingPattern(declaration.parent)) {
+                    /**
+                     * ignore starts with underscore names _
+                     * const { a: _a } = { a: 1 }
+                     */
+                    return !!(declaration.propertyName && isIdentifierThatStartsWithUnderscore(declaration.name));
+                }
+                return isIdentifierThatStartsWithUnderscore(declaration.name);
             }
-
             return isAmbientModule(declaration) ||
                 (isVariableDeclaration(declaration) && isForInOrOfStatement(declaration.parent.parent) || isImportedDeclaration(declaration)) && isIdentifierThatStartsWithUnderscore(declaration.name!);
         }
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.errors.txt b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.errors.txt
new file mode 100644
index 0000000000000..58eccaee1e8f5
--- /dev/null
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.errors.txt
@@ -0,0 +1,145 @@
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(12,17): error TS6133: 'b1' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(13,12): error TS6133: 'a2' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(14,12): error TS6133: 'a3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(14,16): error TS6133: 'b3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(23,12): error TS6133: 'a3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(23,18): error TS6133: 'b3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(23,22): error TS6133: 'c3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(23,28): error TS6133: 'd3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(23,32): error TS6133: 'e3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(37,22): error TS6133: 'b1' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(38,13): error TS6133: 'a2' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(39,11): error TS6198: All destructured elements are unused.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(68,9): error TS6133: 'a3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(70,18): error TS6198: All destructured elements are unused.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(74,9): error TS6133: 'c3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(75,9): error TS6133: 'd3' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts(81,11): error TS6198: All destructured elements are unused.
+
+
+==== tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts (17 errors) ====
+    function t1() {
+        const [_a1, b1] = [1, 2];
+        console.log(b1);
+    
+        const [a2, _b2] = [1, 2];
+        console.log(a2);
+    
+        const [_a3, _b3] = [1, 2];
+    }
+    
+    function t2() {
+        const [_a1, b1] = [1, 2];
+                    ~~
+!!! error TS6133: 'b1' is declared but its value is never read.
+        const [a2, _b2] = [1, 2];
+               ~~
+!!! error TS6133: 'a2' is declared but its value is never read.
+        const [a3, b3] = [1, 2];
+               ~~
+!!! error TS6133: 'a3' is declared but its value is never read.
+                   ~~
+!!! error TS6133: 'b3' is declared but its value is never read.
+    }
+    
+    function t3() {
+        const [_a1, [[_b1, c1]], d1, _e1] = [1, [[2, 3]], 4, 5];
+        console.log(c1, d1);
+    
+        const [_a2, [[_b2, _c2]], _d2, _e2] = [1, [[2, 3]], 4, 5];
+    
+        const [a3, [[b3, c3]], d3, e3] = [1, [[2, 3]], 4, 5];
+               ~~
+!!! error TS6133: 'a3' is declared but its value is never read.
+                     ~~
+!!! error TS6133: 'b3' is declared but its value is never read.
+                         ~~
+!!! error TS6133: 'c3' is declared but its value is never read.
+                               ~~
+!!! error TS6133: 'd3' is declared but its value is never read.
+                                   ~~
+!!! error TS6133: 'e3' is declared but its value is never read.
+    }
+    
+    function t4() {
+        const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+        console.log(b1);
+    
+        const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+        console.log(a2);
+    
+        const { a3: _a3, b3: _b3 } = { a3: 1, b3: 1 };
+    }
+    
+    function t5() {
+        const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+                         ~~
+!!! error TS6133: 'b1' is declared but its value is never read.
+        const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+                ~~
+!!! error TS6133: 'a2' is declared but its value is never read.
+        const { a3, b3 } = { a3: 1, b3: 1 };
+              ~~~~~~~~~~
+!!! error TS6198: All destructured elements are unused.
+    }
+    
+    function t6() {
+        const {
+            a1: _a1,
+            b1: {
+                b11: {
+                    b111: _b111,
+                    b112
+                }
+            },
+            c1,
+            d1: _d1
+        } = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 };
+        console.log(b112, c1);
+    
+        const {
+            a2: _a2,
+            b2: {
+                b21: {
+                    b211: _b211, b212: _b212
+                }
+            },
+            c2: _c2,
+            d2: _d2
+        } = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 };
+    
+        const {
+            a3,
+            ~~
+!!! error TS6133: 'a3' is declared but its value is never read.
+            b3: {
+                b31: {
+                     ~
+                    b311, b312
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+                }
+    ~~~~~~~~~~~~~
+!!! error TS6198: All destructured elements are unused.
+            },
+            c3,
+            ~~
+!!! error TS6133: 'c3' is declared but its value is never read.
+            d3
+            ~~
+!!! error TS6133: 'd3' is declared but its value is never read.
+        } = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 };
+    }
+    
+    function t7() {
+        // error
+        const { _a1, _b1 } = { _a1: 1, _b1: 1 };
+              ~~~~~~~~~~~~
+!!! error TS6198: All destructured elements are unused.
+    
+        // ok
+        const { a2: _a2, b2: _b2 } = { a2: 1, b2: 1 };
+    
+        // ok
+        const { _a3: _ignoreA3, _b3: _ignoreB3 } = { _a3: 1, _b3: 1 };
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.js b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.js
new file mode 100644
index 0000000000000..6e6846f470a59
--- /dev/null
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.js
@@ -0,0 +1,136 @@
+//// [unusedVariablesWithUnderscoreInBindingElement.ts]
+function t1() {
+    const [_a1, b1] = [1, 2];
+    console.log(b1);
+
+    const [a2, _b2] = [1, 2];
+    console.log(a2);
+
+    const [_a3, _b3] = [1, 2];
+}
+
+function t2() {
+    const [_a1, b1] = [1, 2];
+    const [a2, _b2] = [1, 2];
+    const [a3, b3] = [1, 2];
+}
+
+function t3() {
+    const [_a1, [[_b1, c1]], d1, _e1] = [1, [[2, 3]], 4, 5];
+    console.log(c1, d1);
+
+    const [_a2, [[_b2, _c2]], _d2, _e2] = [1, [[2, 3]], 4, 5];
+
+    const [a3, [[b3, c3]], d3, e3] = [1, [[2, 3]], 4, 5];
+}
+
+function t4() {
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+    console.log(b1);
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+    console.log(a2);
+
+    const { a3: _a3, b3: _b3 } = { a3: 1, b3: 1 };
+}
+
+function t5() {
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+    const { a3, b3 } = { a3: 1, b3: 1 };
+}
+
+function t6() {
+    const {
+        a1: _a1,
+        b1: {
+            b11: {
+                b111: _b111,
+                b112
+            }
+        },
+        c1,
+        d1: _d1
+    } = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 };
+    console.log(b112, c1);
+
+    const {
+        a2: _a2,
+        b2: {
+            b21: {
+                b211: _b211, b212: _b212
+            }
+        },
+        c2: _c2,
+        d2: _d2
+    } = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 };
+
+    const {
+        a3,
+        b3: {
+            b31: {
+                b311, b312
+            }
+        },
+        c3,
+        d3
+    } = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 };
+}
+
+function t7() {
+    // error
+    const { _a1, _b1 } = { _a1: 1, _b1: 1 };
+
+    // ok
+    const { a2: _a2, b2: _b2 } = { a2: 1, b2: 1 };
+
+    // ok
+    const { _a3: _ignoreA3, _b3: _ignoreB3 } = { _a3: 1, _b3: 1 };
+}
+
+
+//// [unusedVariablesWithUnderscoreInBindingElement.js]
+function t1() {
+    var _a = [1, 2], _a1 = _a[0], b1 = _a[1];
+    console.log(b1);
+    var _b = [1, 2], a2 = _b[0], _b2 = _b[1];
+    console.log(a2);
+    var _c = [1, 2], _a3 = _c[0], _b3 = _c[1];
+}
+function t2() {
+    var _a = [1, 2], _a1 = _a[0], b1 = _a[1];
+    var _b = [1, 2], a2 = _b[0], _b2 = _b[1];
+    var _c = [1, 2], a3 = _c[0], b3 = _c[1];
+}
+function t3() {
+    var _a = [1, [[2, 3]], 4, 5], _a1 = _a[0], _b = _a[1][0], _b1 = _b[0], c1 = _b[1], d1 = _a[2], _e1 = _a[3];
+    console.log(c1, d1);
+    var _c = [1, [[2, 3]], 4, 5], _a2 = _c[0], _d = _c[1][0], _b2 = _d[0], _c2 = _d[1], _d2 = _c[2], _e2 = _c[3];
+    var _e = [1, [[2, 3]], 4, 5], a3 = _e[0], _f = _e[1][0], b3 = _f[0], c3 = _f[1], d3 = _e[2], e3 = _e[3];
+}
+function t4() {
+    var _a = { a1: 1, b1: 1 }, _a1 = _a.a1, b1 = _a.b1;
+    console.log(b1);
+    var _b = { a2: 1, b2: 1 }, a2 = _b.a2, _b2 = _b.b2;
+    console.log(a2);
+    var _c = { a3: 1, b3: 1 }, _a3 = _c.a3, _b3 = _c.b3;
+}
+function t5() {
+    var _a = { a1: 1, b1: 1 }, _a1 = _a.a1, b1 = _a.b1;
+    var _b = { a2: 1, b2: 1 }, a2 = _b.a2, _b2 = _b.b2;
+    var _c = { a3: 1, b3: 1 }, a3 = _c.a3, b3 = _c.b3;
+}
+function t6() {
+    var _a = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 }, _a1 = _a.a1, _b = _a.b1.b11, _b111 = _b.b111, b112 = _b.b112, c1 = _a.c1, _d1 = _a.d1;
+    console.log(b112, c1);
+    var _c = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 }, _a2 = _c.a2, _d = _c.b2.b21, _b211 = _d.b211, _b212 = _d.b212, _c2 = _c.c2, _d2 = _c.d2;
+    var _e = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 }, a3 = _e.a3, _f = _e.b3.b31, b311 = _f.b311, b312 = _f.b312, c3 = _e.c3, d3 = _e.d3;
+}
+function t7() {
+    // error
+    var _a = { _a1: 1, _b1: 1 }, _a1 = _a._a1, _b1 = _a._b1;
+    // ok
+    var _b = { a2: 1, b2: 1 }, _a2 = _b.a2, _b2 = _b.b2;
+    // ok
+    var _c = { _a3: 1, _b3: 1 }, _ignoreA3 = _c._a3, _ignoreB3 = _c._b3;
+}
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.symbols b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.symbols
new file mode 100644
index 0000000000000..0c5367a9ed64f
--- /dev/null
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.symbols
@@ -0,0 +1,279 @@
+=== tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts ===
+function t1() {
+>t1 : Symbol(t1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 0, 0))
+
+    const [_a1, b1] = [1, 2];
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 1, 11))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 1, 15))
+
+    console.log(b1);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 1, 15))
+
+    const [a2, _b2] = [1, 2];
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 4, 11))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 4, 14))
+
+    console.log(a2);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 4, 11))
+
+    const [_a3, _b3] = [1, 2];
+>_a3 : Symbol(_a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 7, 11))
+>_b3 : Symbol(_b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 7, 15))
+}
+
+function t2() {
+>t2 : Symbol(t2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 8, 1))
+
+    const [_a1, b1] = [1, 2];
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 11, 11))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 11, 15))
+
+    const [a2, _b2] = [1, 2];
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 12, 11))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 12, 14))
+
+    const [a3, b3] = [1, 2];
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 13, 11))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 13, 14))
+}
+
+function t3() {
+>t3 : Symbol(t3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 14, 1))
+
+    const [_a1, [[_b1, c1]], d1, _e1] = [1, [[2, 3]], 4, 5];
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 11))
+>_b1 : Symbol(_b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 18))
+>c1 : Symbol(c1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 22))
+>d1 : Symbol(d1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 28))
+>_e1 : Symbol(_e1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 32))
+
+    console.log(c1, d1);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>c1 : Symbol(c1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 22))
+>d1 : Symbol(d1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 17, 28))
+
+    const [_a2, [[_b2, _c2]], _d2, _e2] = [1, [[2, 3]], 4, 5];
+>_a2 : Symbol(_a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 20, 11))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 20, 18))
+>_c2 : Symbol(_c2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 20, 22))
+>_d2 : Symbol(_d2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 20, 29))
+>_e2 : Symbol(_e2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 20, 34))
+
+    const [a3, [[b3, c3]], d3, e3] = [1, [[2, 3]], 4, 5];
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 22, 11))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 22, 17))
+>c3 : Symbol(c3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 22, 20))
+>d3 : Symbol(d3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 22, 26))
+>e3 : Symbol(e3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 22, 30))
+}
+
+function t4() {
+>t4 : Symbol(t4, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 23, 1))
+
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 29))
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 11))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 20))
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 29))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 36))
+
+    console.log(b1);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 26, 20))
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 11))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 36))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 15))
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 29))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 36))
+
+    console.log(a2);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 29, 11))
+
+    const { a3: _a3, b3: _b3 } = { a3: 1, b3: 1 };
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 34))
+>_a3 : Symbol(_a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 11))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 41))
+>_b3 : Symbol(_b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 20))
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 34))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 32, 41))
+}
+
+function t5() {
+>t5 : Symbol(t5, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 33, 1))
+
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 36, 29))
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 36, 11))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 36, 20))
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 36, 29))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 36, 36))
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 37, 11))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 37, 36))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 37, 15))
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 37, 29))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 37, 36))
+
+    const { a3, b3 } = { a3: 1, b3: 1 };
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 38, 11))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 38, 15))
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 38, 24))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 38, 31))
+}
+
+function t6() {
+>t6 : Symbol(t6, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 39, 1))
+
+    const {
+        a1: _a1,
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 9))
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 42, 11))
+
+        b1: {
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 16))
+
+            b11: {
+>b11 : Symbol(b11, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 22))
+
+                b111: _b111,
+>b111 : Symbol(b111, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 29))
+>_b111 : Symbol(_b111, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 45, 18))
+
+                b112
+>b112 : Symbol(b112, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 46, 28))
+            }
+        },
+        c1,
+>c1 : Symbol(c1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 49, 10))
+
+        d1: _d1
+>d1 : Symbol(d1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 58))
+>_d1 : Symbol(_d1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 50, 11))
+
+    } = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 };
+>a1 : Symbol(a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 9))
+>b1 : Symbol(b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 16))
+>b11 : Symbol(b11, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 22))
+>b111 : Symbol(b111, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 29))
+>b112 : Symbol(b112, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 38))
+>c1 : Symbol(c1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 51))
+>d1 : Symbol(d1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 52, 58))
+
+    console.log(b112, c1);
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>b112 : Symbol(b112, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 46, 28))
+>c1 : Symbol(c1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 49, 10))
+
+    const {
+        a2: _a2,
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 9))
+>_a2 : Symbol(_a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 55, 11))
+
+        b2: {
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 16))
+
+            b21: {
+>b21 : Symbol(b21, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 22))
+
+                b211: _b211, b212: _b212
+>b211 : Symbol(b211, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 29))
+>_b211 : Symbol(_b211, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 58, 18))
+>b212 : Symbol(b212, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 38))
+>_b212 : Symbol(_b212, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 59, 28))
+            }
+        },
+        c2: _c2,
+>c2 : Symbol(c2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 51))
+>_c2 : Symbol(_c2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 61, 10))
+
+        d2: _d2
+>d2 : Symbol(d2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 58))
+>_d2 : Symbol(_d2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 62, 16))
+
+    } = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 };
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 9))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 16))
+>b21 : Symbol(b21, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 22))
+>b211 : Symbol(b211, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 29))
+>b212 : Symbol(b212, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 38))
+>c2 : Symbol(c2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 51))
+>d2 : Symbol(d2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 64, 58))
+
+    const {
+        a3,
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 66, 11))
+
+        b3: {
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 16))
+
+            b31: {
+>b31 : Symbol(b31, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 22))
+
+                b311, b312
+>b311 : Symbol(b311, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 69, 18))
+>b312 : Symbol(b312, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 70, 21))
+            }
+        },
+        c3,
+>c3 : Symbol(c3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 72, 10))
+
+        d3
+>d3 : Symbol(d3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 73, 11))
+
+    } = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 };
+>a3 : Symbol(a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 9))
+>b3 : Symbol(b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 16))
+>b31 : Symbol(b31, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 22))
+>b311 : Symbol(b311, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 29))
+>b312 : Symbol(b312, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 38))
+>c3 : Symbol(c3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 51))
+>d3 : Symbol(d3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 75, 58))
+}
+
+function t7() {
+>t7 : Symbol(t7, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 76, 1))
+
+    // error
+    const { _a1, _b1 } = { _a1: 1, _b1: 1 };
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 80, 11))
+>_b1 : Symbol(_b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 80, 16))
+>_a1 : Symbol(_a1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 80, 26))
+>_b1 : Symbol(_b1, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 80, 34))
+
+    // ok
+    const { a2: _a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 34))
+>_a2 : Symbol(_a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 11))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 41))
+>_b2 : Symbol(_b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 20))
+>a2 : Symbol(a2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 34))
+>b2 : Symbol(b2, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 83, 41))
+
+    // ok
+    const { _a3: _ignoreA3, _b3: _ignoreB3 } = { _a3: 1, _b3: 1 };
+>_a3 : Symbol(_a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 48))
+>_ignoreA3 : Symbol(_ignoreA3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 11))
+>_b3 : Symbol(_b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 56))
+>_ignoreB3 : Symbol(_ignoreB3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 27))
+>_a3 : Symbol(_a3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 48))
+>_b3 : Symbol(_b3, Decl(unusedVariablesWithUnderscoreInBindingElement.ts, 86, 56))
+}
+
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.types b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.types
new file mode 100644
index 0000000000000..d5d65c91af935
--- /dev/null
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInBindingElement.types
@@ -0,0 +1,378 @@
+=== tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts ===
+function t1() {
+>t1 : () => void
+
+    const [_a1, b1] = [1, 2];
+>_a1 : number
+>b1 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+
+    console.log(b1);
+>console.log(b1) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>b1 : number
+
+    const [a2, _b2] = [1, 2];
+>a2 : number
+>_b2 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+
+    console.log(a2);
+>console.log(a2) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>a2 : number
+
+    const [_a3, _b3] = [1, 2];
+>_a3 : number
+>_b3 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+}
+
+function t2() {
+>t2 : () => void
+
+    const [_a1, b1] = [1, 2];
+>_a1 : number
+>b1 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+
+    const [a2, _b2] = [1, 2];
+>a2 : number
+>_b2 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+
+    const [a3, b3] = [1, 2];
+>a3 : number
+>b3 : number
+>[1, 2] : [number, number]
+>1 : 1
+>2 : 2
+}
+
+function t3() {
+>t3 : () => void
+
+    const [_a1, [[_b1, c1]], d1, _e1] = [1, [[2, 3]], 4, 5];
+>_a1 : number
+>_b1 : number
+>c1 : number
+>d1 : number
+>_e1 : number
+>[1, [[2, 3]], 4, 5] : [number, [[number, number]], number, number]
+>1 : 1
+>[[2, 3]] : [[number, number]]
+>[2, 3] : [number, number]
+>2 : 2
+>3 : 3
+>4 : 4
+>5 : 5
+
+    console.log(c1, d1);
+>console.log(c1, d1) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>c1 : number
+>d1 : number
+
+    const [_a2, [[_b2, _c2]], _d2, _e2] = [1, [[2, 3]], 4, 5];
+>_a2 : number
+>_b2 : number
+>_c2 : number
+>_d2 : number
+>_e2 : number
+>[1, [[2, 3]], 4, 5] : [number, [[number, number]], number, number]
+>1 : 1
+>[[2, 3]] : [[number, number]]
+>[2, 3] : [number, number]
+>2 : 2
+>3 : 3
+>4 : 4
+>5 : 5
+
+    const [a3, [[b3, c3]], d3, e3] = [1, [[2, 3]], 4, 5];
+>a3 : number
+>b3 : number
+>c3 : number
+>d3 : number
+>e3 : number
+>[1, [[2, 3]], 4, 5] : [number, [[number, number]], number, number]
+>1 : 1
+>[[2, 3]] : [[number, number]]
+>[2, 3] : [number, number]
+>2 : 2
+>3 : 3
+>4 : 4
+>5 : 5
+}
+
+function t4() {
+>t4 : () => void
+
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+>a1 : any
+>_a1 : number
+>b1 : number
+>{ a1: 1, b1: 1 } : { a1: number; b1: number; }
+>a1 : number
+>1 : 1
+>b1 : number
+>1 : 1
+
+    console.log(b1);
+>console.log(b1) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>b1 : number
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : number
+>b2 : any
+>_b2 : number
+>{ a2: 1, b2: 1 } : { a2: number; b2: number; }
+>a2 : number
+>1 : 1
+>b2 : number
+>1 : 1
+
+    console.log(a2);
+>console.log(a2) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>a2 : number
+
+    const { a3: _a3, b3: _b3 } = { a3: 1, b3: 1 };
+>a3 : any
+>_a3 : number
+>b3 : any
+>_b3 : number
+>{ a3: 1, b3: 1 } : { a3: number; b3: number; }
+>a3 : number
+>1 : 1
+>b3 : number
+>1 : 1
+}
+
+function t5() {
+>t5 : () => void
+
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+>a1 : any
+>_a1 : number
+>b1 : number
+>{ a1: 1, b1: 1 } : { a1: number; b1: number; }
+>a1 : number
+>1 : 1
+>b1 : number
+>1 : 1
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : number
+>b2 : any
+>_b2 : number
+>{ a2: 1, b2: 1 } : { a2: number; b2: number; }
+>a2 : number
+>1 : 1
+>b2 : number
+>1 : 1
+
+    const { a3, b3 } = { a3: 1, b3: 1 };
+>a3 : number
+>b3 : number
+>{ a3: 1, b3: 1 } : { a3: number; b3: number; }
+>a3 : number
+>1 : 1
+>b3 : number
+>1 : 1
+}
+
+function t6() {
+>t6 : () => void
+
+    const {
+        a1: _a1,
+>a1 : any
+>_a1 : number
+
+        b1: {
+>b1 : any
+
+            b11: {
+>b11 : any
+
+                b111: _b111,
+>b111 : any
+>_b111 : number
+
+                b112
+>b112 : number
+            }
+        },
+        c1,
+>c1 : number
+
+        d1: _d1
+>d1 : any
+>_d1 : number
+
+    } = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 };
+>{ a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 } : { a1: number; b1: { b11: { b111: number; b112: number; }; }; c1: number; d1: number; }
+>a1 : number
+>1 : 1
+>b1 : { b11: { b111: number; b112: number; }; }
+>{ b11: { b111: 1, b112: 1 } } : { b11: { b111: number; b112: number; }; }
+>b11 : { b111: number; b112: number; }
+>{ b111: 1, b112: 1 } : { b111: number; b112: number; }
+>b111 : number
+>1 : 1
+>b112 : number
+>1 : 1
+>c1 : number
+>1 : 1
+>d1 : number
+>1 : 1
+
+    console.log(b112, c1);
+>console.log(b112, c1) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>b112 : number
+>c1 : number
+
+    const {
+        a2: _a2,
+>a2 : any
+>_a2 : number
+
+        b2: {
+>b2 : any
+
+            b21: {
+>b21 : any
+
+                b211: _b211, b212: _b212
+>b211 : any
+>_b211 : number
+>b212 : any
+>_b212 : number
+            }
+        },
+        c2: _c2,
+>c2 : any
+>_c2 : number
+
+        d2: _d2
+>d2 : any
+>_d2 : number
+
+    } = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 };
+>{ a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 } : { a2: number; b2: { b21: { b211: number; b212: number; }; }; c2: number; d2: number; }
+>a2 : number
+>1 : 1
+>b2 : { b21: { b211: number; b212: number; }; }
+>{ b21: { b211: 1, b212: 1 } } : { b21: { b211: number; b212: number; }; }
+>b21 : { b211: number; b212: number; }
+>{ b211: 1, b212: 1 } : { b211: number; b212: number; }
+>b211 : number
+>1 : 1
+>b212 : number
+>1 : 1
+>c2 : number
+>1 : 1
+>d2 : number
+>1 : 1
+
+    const {
+        a3,
+>a3 : number
+
+        b3: {
+>b3 : any
+
+            b31: {
+>b31 : any
+
+                b311, b312
+>b311 : number
+>b312 : number
+            }
+        },
+        c3,
+>c3 : number
+
+        d3
+>d3 : number
+
+    } = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 };
+>{ a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 } : { a3: number; b3: { b31: { b311: number; b312: number; }; }; c3: number; d3: number; }
+>a3 : number
+>1 : 1
+>b3 : { b31: { b311: number; b312: number; }; }
+>{ b31: { b311: 1, b312: 1 } } : { b31: { b311: number; b312: number; }; }
+>b31 : { b311: number; b312: number; }
+>{ b311: 1, b312: 1 } : { b311: number; b312: number; }
+>b311 : number
+>1 : 1
+>b312 : number
+>1 : 1
+>c3 : number
+>1 : 1
+>d3 : number
+>1 : 1
+}
+
+function t7() {
+>t7 : () => void
+
+    // error
+    const { _a1, _b1 } = { _a1: 1, _b1: 1 };
+>_a1 : number
+>_b1 : number
+>{ _a1: 1, _b1: 1 } : { _a1: number; _b1: number; }
+>_a1 : number
+>1 : 1
+>_b1 : number
+>1 : 1
+
+    // ok
+    const { a2: _a2, b2: _b2 } = { a2: 1, b2: 1 };
+>a2 : any
+>_a2 : number
+>b2 : any
+>_b2 : number
+>{ a2: 1, b2: 1 } : { a2: number; b2: number; }
+>a2 : number
+>1 : 1
+>b2 : number
+>1 : 1
+
+    // ok
+    const { _a3: _ignoreA3, _b3: _ignoreB3 } = { _a3: 1, _b3: 1 };
+>_a3 : any
+>_ignoreA3 : number
+>_b3 : any
+>_ignoreB3 : number
+>{ _a3: 1, _b3: 1 } : { _a3: number; _b3: number; }
+>_a3 : number
+>1 : 1
+>_b3 : number
+>1 : 1
+}
+
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.errors.txt b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.errors.txt
new file mode 100644
index 0000000000000..38476fd6c796a
--- /dev/null
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.errors.txt
@@ -0,0 +1,56 @@
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(15,21): error TS6133: 'b' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(17,17): error TS6133: 'a' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(19,17): error TS6133: 'a' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(19,20): error TS6133: 'b' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(23,23): error TS6133: 'b' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(25,19): error TS6133: 'a' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(27,19): error TS6133: 'a' is declared but its value is never read.
+tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts(27,22): error TS6133: 'b' is declared but its value is never read.
+
+
+==== tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts (8 errors) ====
+    function t1() {
+        for (const [_a, b] of [['key', 1]]) {
+            console.log(b);
+        }
+    
+        for (const [a, _b] of [['key', 1]]) {
+            console.log(a);
+        }
+    
+        for (const [_a, _b] of [['key', 1]]) {}
+    }
+    
+    
+    function t2() {
+        for (const [_a, b] of [['key', 1]]) {}
+                        ~
+!!! error TS6133: 'b' is declared but its value is never read.
+    
+        for (const [a, _b] of [['key', 1]]) {}
+                    ~
+!!! error TS6133: 'a' is declared but its value is never read.
+    
+        for (const [a, b] of [['key', 1]]) {}
+                    ~
+!!! error TS6133: 'a' is declared but its value is never read.
+                       ~
+!!! error TS6133: 'b' is declared but its value is never read.
+    }
+    
+    function t3() {
+        for (const [[[_a, b]]] of [[[['key', 1]]]]) {}
+                          ~
+!!! error TS6133: 'b' is declared but its value is never read.
+    
+        for (const [[[a, _b]]] of [[[['key', 1]]]]) {}
+                      ~
+!!! error TS6133: 'a' is declared but its value is never read.
+    
+        for (const [[[a, b]]] of [[[['key', 1]]]]) {}
+                      ~
+!!! error TS6133: 'a' is declared but its value is never read.
+                         ~
+!!! error TS6133: 'b' is declared but its value is never read.
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.js b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.js
index 0c08ba841931f..3418db8795e79 100644
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.js
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.js
@@ -1,5 +1,5 @@
 //// [unusedVariablesWithUnderscoreInForOfLoop.ts]
-function f() {
+function t1() {
     for (const [_a, b] of [['key', 1]]) {
         console.log(b);
     }
@@ -10,10 +10,27 @@ function f() {
 
     for (const [_a, _b] of [['key', 1]]) {}
 }
+
+
+function t2() {
+    for (const [_a, b] of [['key', 1]]) {}
+
+    for (const [a, _b] of [['key', 1]]) {}
+
+    for (const [a, b] of [['key', 1]]) {}
+}
+
+function t3() {
+    for (const [[[_a, b]]] of [[[['key', 1]]]]) {}
+
+    for (const [[[a, _b]]] of [[[['key', 1]]]]) {}
+
+    for (const [[[a, b]]] of [[[['key', 1]]]]) {}
+}
 
 
 //// [unusedVariablesWithUnderscoreInForOfLoop.js]
-function f() {
+function t1() {
     for (var _i = 0, _c = [['key', 1]]; _i < _c.length; _i++) {
         var _d = _c[_i], _a = _d[0], b = _d[1];
         console.log(b);
@@ -26,3 +43,25 @@ function f() {
         var _k = _j[_h], _a = _k[0], _b = _k[1];
     }
 }
+function t2() {
+    for (var _i = 0, _c = [['key', 1]]; _i < _c.length; _i++) {
+        var _d = _c[_i], _a = _d[0], b = _d[1];
+    }
+    for (var _e = 0, _f = [['key', 1]]; _e < _f.length; _e++) {
+        var _g = _f[_e], a = _g[0], _b = _g[1];
+    }
+    for (var _h = 0, _j = [['key', 1]]; _h < _j.length; _h++) {
+        var _k = _j[_h], a = _k[0], b = _k[1];
+    }
+}
+function t3() {
+    for (var _i = 0, _c = [[[['key', 1]]]]; _i < _c.length; _i++) {
+        var _d = _c[_i][0][0], _a = _d[0], b = _d[1];
+    }
+    for (var _e = 0, _f = [[[['key', 1]]]]; _e < _f.length; _e++) {
+        var _g = _f[_e][0][0], a = _g[0], _b = _g[1];
+    }
+    for (var _h = 0, _j = [[[['key', 1]]]]; _h < _j.length; _h++) {
+        var _k = _j[_h][0][0], a = _k[0], b = _k[1];
+    }
+}
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.symbols b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.symbols
index d6c97536d3b4f..2bc45a8911a2f 100644
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.symbols
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.symbols
@@ -1,6 +1,6 @@
 === tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts ===
-function f() {
->f : Symbol(f, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 0, 0))
+function t1() {
+>t1 : Symbol(t1, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 0, 0))
 
     for (const [_a, b] of [['key', 1]]) {
 >_a : Symbol(_a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 1, 16))
@@ -29,3 +29,36 @@ function f() {
 >_b : Symbol(_b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 9, 19))
 }
 
+
+function t2() {
+>t2 : Symbol(t2, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 10, 1))
+
+    for (const [_a, b] of [['key', 1]]) {}
+>_a : Symbol(_a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 14, 16))
+>b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 14, 19))
+
+    for (const [a, _b] of [['key', 1]]) {}
+>a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 16, 16))
+>_b : Symbol(_b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 16, 18))
+
+    for (const [a, b] of [['key', 1]]) {}
+>a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 18, 16))
+>b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 18, 18))
+}
+
+function t3() {
+>t3 : Symbol(t3, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 19, 1))
+
+    for (const [[[_a, b]]] of [[[['key', 1]]]]) {}
+>_a : Symbol(_a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 22, 18))
+>b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 22, 21))
+
+    for (const [[[a, _b]]] of [[[['key', 1]]]]) {}
+>a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 24, 18))
+>_b : Symbol(_b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 24, 20))
+
+    for (const [[[a, b]]] of [[[['key', 1]]]]) {}
+>a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 26, 18))
+>b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop.ts, 26, 20))
+}
+
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.types b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.types
index eb1ce0b0bbeae..b86d820a46b91 100644
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.types
+++ b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop.types
@@ -1,6 +1,6 @@
 === tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts ===
-function f() {
->f : () => void
+function t1() {
+>t1 : () => void
 
     for (const [_a, b] of [['key', 1]]) {
 >_a : string | number
@@ -43,3 +43,66 @@ function f() {
 >1 : 1
 }
 
+
+function t2() {
+>t2 : () => void
+
+    for (const [_a, b] of [['key', 1]]) {}
+>_a : string | number
+>b : string | number
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+
+    for (const [a, _b] of [['key', 1]]) {}
+>a : string | number
+>_b : string | number
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+
+    for (const [a, b] of [['key', 1]]) {}
+>a : string | number
+>b : string | number
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+}
+
+function t3() {
+>t3 : () => void
+
+    for (const [[[_a, b]]] of [[[['key', 1]]]]) {}
+>_a : string | number
+>b : string | number
+>[[[['key', 1]]]] : (string | number)[][][][]
+>[[['key', 1]]] : (string | number)[][][]
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+
+    for (const [[[a, _b]]] of [[[['key', 1]]]]) {}
+>a : string | number
+>_b : string | number
+>[[[['key', 1]]]] : (string | number)[][][][]
+>[[['key', 1]]] : (string | number)[][][]
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+
+    for (const [[[a, b]]] of [[[['key', 1]]]]) {}
+>a : string | number
+>b : string | number
+>[[[['key', 1]]]] : (string | number)[][][][]
+>[[['key', 1]]] : (string | number)[][][]
+>[['key', 1]] : (string | number)[][]
+>['key', 1] : (string | number)[]
+>'key' : "key"
+>1 : 1
+}
+
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.errors.txt b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.errors.txt
deleted file mode 100644
index fa8b7d9d55caf..0000000000000
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.errors.txt
+++ /dev/null
@@ -1,23 +0,0 @@
-tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts(2,21): error TS6133: 'b' is declared but its value is never read.
-tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts(4,17): error TS6133: 'a' is declared but its value is never read.
-tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts(6,17): error TS6133: 'a' is declared but its value is never read.
-tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts(6,20): error TS6133: 'b' is declared but its value is never read.
-
-
-==== tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts (4 errors) ====
-    function f() {
-        for (const [_a, b] of [['key', 1]]) {}
-                        ~
-!!! error TS6133: 'b' is declared but its value is never read.
-    
-        for (const [a, _b] of [['key', 1]]) {}
-                    ~
-!!! error TS6133: 'a' is declared but its value is never read.
-    
-        for (const [a, b] of [['key', 1]]) {}
-                    ~
-!!! error TS6133: 'a' is declared but its value is never read.
-                       ~
-!!! error TS6133: 'b' is declared but its value is never read.
-    }
-    
\ No newline at end of file
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.js b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.js
deleted file mode 100644
index bb5ecbfe974c2..0000000000000
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.js
+++ /dev/null
@@ -1,22 +0,0 @@
-//// [unusedVariablesWithUnderscoreInForOfLoop1.ts]
-function f() {
-    for (const [_a, b] of [['key', 1]]) {}
-
-    for (const [a, _b] of [['key', 1]]) {}
-
-    for (const [a, b] of [['key', 1]]) {}
-}
-
-
-//// [unusedVariablesWithUnderscoreInForOfLoop1.js]
-function f() {
-    for (var _i = 0, _c = [['key', 1]]; _i < _c.length; _i++) {
-        var _d = _c[_i], _a = _d[0], b = _d[1];
-    }
-    for (var _e = 0, _f = [['key', 1]]; _e < _f.length; _e++) {
-        var _g = _f[_e], a = _g[0], _b = _g[1];
-    }
-    for (var _h = 0, _j = [['key', 1]]; _h < _j.length; _h++) {
-        var _k = _j[_h], a = _k[0], b = _k[1];
-    }
-}
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.symbols b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.symbols
deleted file mode 100644
index b98293944afd4..0000000000000
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.symbols
+++ /dev/null
@@ -1,17 +0,0 @@
-=== tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts ===
-function f() {
->f : Symbol(f, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 0, 0))
-
-    for (const [_a, b] of [['key', 1]]) {}
->_a : Symbol(_a, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 1, 16))
->b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 1, 19))
-
-    for (const [a, _b] of [['key', 1]]) {}
->a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 3, 16))
->_b : Symbol(_b, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 3, 18))
-
-    for (const [a, b] of [['key', 1]]) {}
->a : Symbol(a, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 5, 16))
->b : Symbol(b, Decl(unusedVariablesWithUnderscoreInForOfLoop1.ts, 5, 18))
-}
-
diff --git a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.types b/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.types
deleted file mode 100644
index 100e87191482f..0000000000000
--- a/tests/baselines/reference/unusedVariablesWithUnderscoreInForOfLoop1.types
+++ /dev/null
@@ -1,29 +0,0 @@
-=== tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts ===
-function f() {
->f : () => void
-
-    for (const [_a, b] of [['key', 1]]) {}
->_a : string | number
->b : string | number
->[['key', 1]] : (string | number)[][]
->['key', 1] : (string | number)[]
->'key' : "key"
->1 : 1
-
-    for (const [a, _b] of [['key', 1]]) {}
->a : string | number
->_b : string | number
->[['key', 1]] : (string | number)[][]
->['key', 1] : (string | number)[]
->'key' : "key"
->1 : 1
-
-    for (const [a, b] of [['key', 1]]) {}
->a : string | number
->b : string | number
->[['key', 1]] : (string | number)[][]
->['key', 1] : (string | number)[]
->'key' : "key"
->1 : 1
-}
-
diff --git a/tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts b/tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts
new file mode 100644
index 0000000000000..23b732d51edb9
--- /dev/null
+++ b/tests/cases/compiler/unusedVariablesWithUnderscoreInBindingElement.ts
@@ -0,0 +1,90 @@
+// @noUnusedLocals: true
+
+function t1() {
+    const [_a1, b1] = [1, 2];
+    console.log(b1);
+
+    const [a2, _b2] = [1, 2];
+    console.log(a2);
+
+    const [_a3, _b3] = [1, 2];
+}
+
+function t2() {
+    const [_a1, b1] = [1, 2];
+    const [a2, _b2] = [1, 2];
+    const [a3, b3] = [1, 2];
+}
+
+function t3() {
+    const [_a1, [[_b1, c1]], d1, _e1] = [1, [[2, 3]], 4, 5];
+    console.log(c1, d1);
+
+    const [_a2, [[_b2, _c2]], _d2, _e2] = [1, [[2, 3]], 4, 5];
+
+    const [a3, [[b3, c3]], d3, e3] = [1, [[2, 3]], 4, 5];
+}
+
+function t4() {
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+    console.log(b1);
+
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+    console.log(a2);
+
+    const { a3: _a3, b3: _b3 } = { a3: 1, b3: 1 };
+}
+
+function t5() {
+    const { a1: _a1, b1 } = { a1: 1, b1: 1 };
+    const { a2, b2: _b2 } = { a2: 1, b2: 1 };
+    const { a3, b3 } = { a3: 1, b3: 1 };
+}
+
+function t6() {
+    const {
+        a1: _a1,
+        b1: {
+            b11: {
+                b111: _b111,
+                b112
+            }
+        },
+        c1,
+        d1: _d1
+    } = { a1: 1, b1: { b11: { b111: 1, b112: 1 } }, c1: 1, d1: 1 };
+    console.log(b112, c1);
+
+    const {
+        a2: _a2,
+        b2: {
+            b21: {
+                b211: _b211, b212: _b212
+            }
+        },
+        c2: _c2,
+        d2: _d2
+    } = { a2: 1, b2: { b21: { b211: 1, b212: 1 } }, c2: 1, d2: 1 };
+
+    const {
+        a3,
+        b3: {
+            b31: {
+                b311, b312
+            }
+        },
+        c3,
+        d3
+    } = { a3: 1, b3: { b31: { b311: 1, b312: 1 } }, c3: 1, d3: 1 };
+}
+
+function t7() {
+    // error
+    const { _a1, _b1 } = { _a1: 1, _b1: 1 };
+
+    // ok
+    const { a2: _a2, b2: _b2 } = { a2: 1, b2: 1 };
+
+    // ok
+    const { _a3: _ignoreA3, _b3: _ignoreB3 } = { _a3: 1, _b3: 1 };
+}
diff --git a/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts b/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts
index 064e1971ead3d..0bd35321760d9 100644
--- a/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts
+++ b/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop.ts
@@ -1,6 +1,6 @@
-//@noUnusedLocals:true
+// @noUnusedLocals: true
 
-function f() {
+function t1() {
     for (const [_a, b] of [['key', 1]]) {
         console.log(b);
     }
@@ -11,3 +11,20 @@ function f() {
 
     for (const [_a, _b] of [['key', 1]]) {}
 }
+
+
+function t2() {
+    for (const [_a, b] of [['key', 1]]) {}
+
+    for (const [a, _b] of [['key', 1]]) {}
+
+    for (const [a, b] of [['key', 1]]) {}
+}
+
+function t3() {
+    for (const [[[_a, b]]] of [[[['key', 1]]]]) {}
+
+    for (const [[[a, _b]]] of [[[['key', 1]]]]) {}
+
+    for (const [[[a, b]]] of [[[['key', 1]]]]) {}
+}
diff --git a/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts b/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts
deleted file mode 100644
index 0848f20d34a1d..0000000000000
--- a/tests/cases/compiler/unusedVariablesWithUnderscoreInForOfLoop1.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-//@noUnusedLocals:true
-
-function f() {
-    for (const [_a, b] of [['key', 1]]) {}
-
-    for (const [a, _b] of [['key', 1]]) {}
-
-    for (const [a, b] of [['key', 1]]) {}
-}