v8/test/mjsunit/es6/block-let-declaration.js

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// Test let declarations in various settings.

"use strict";

// Global
let x;
let y = 2;
const z = 4;
class c { static foo() { return 1; } }

// Block local
{
  let y;
  let x = 3;
  const z = 5;
  class c { static foo() { return 2; } }
}

assertEquals(undefined, x);
assertEquals(2,y);
assertEquals(4,z);
assertEquals(1, c.foo());

if (true) {
  let y;
  assertEquals(undefined, y);
}

// Invalid declarations are early errors in harmony mode and thus should trigger
// an exception in eval code during parsing, before even compiling or executing
// the code. Thus the generated function is not called here.
function TestLocalThrows(str, expect) {
  assertThrows("(function(arg){ 'use strict'; " + str + "})", expect);
}

function TestLocalDoesNotThrow(str) {
  assertDoesNotThrow("(function(arg){ 'use strict'; " + str + "})()");
}

// Test let declarations in statement positions.
TestLocalThrows("if (true) let x;", SyntaxError);
TestLocalThrows("if (true) {} else let x;", SyntaxError);
TestLocalThrows("do let x; while (false)", SyntaxError);
TestLocalThrows("while (false) let x;", SyntaxError);
TestLocalThrows("label: let x;", SyntaxError);
TestLocalThrows("for (;false;) let x;", SyntaxError);
TestLocalDoesNotThrow("switch (true) { case true: let x; }");
TestLocalDoesNotThrow("switch (true) { default: let x; }");

// Test const declarations with initialisers in statement positions.
TestLocalThrows("if (true) const x = 1;", SyntaxError);
TestLocalThrows("if (true) {} else const x = 1;", SyntaxError);
TestLocalThrows("do const x = 1; while (false)", SyntaxError);
TestLocalThrows("while (false) const x = 1;", SyntaxError);
TestLocalThrows("label: const x = 1;", SyntaxError);
TestLocalThrows("for (;false;) const x = 1;", SyntaxError);
TestLocalDoesNotThrow("switch (true) { case true: const x = 1; }");
TestLocalDoesNotThrow("switch (true) { default: const x = 1; }");

// Test const declarations without initialisers.
TestLocalThrows("const x;", SyntaxError);
TestLocalThrows("const x = 1, y;", SyntaxError);
TestLocalThrows("const x, y = 1;", SyntaxError);

// Test const declarations without initialisers in statement positions.
TestLocalThrows("if (true) const x;", SyntaxError);
TestLocalThrows("if (true) {} else const x;", SyntaxError);
TestLocalThrows("do const x; while (false)", SyntaxError);
TestLocalThrows("while (false) const x;", SyntaxError);
TestLocalThrows("label: const x;", SyntaxError);
TestLocalThrows("for (;false;) const x;", SyntaxError);
TestLocalThrows("switch (true) { case true: const x; }", SyntaxError);
TestLocalThrows("switch (true) { default: const x; }", SyntaxError);

// Test var declarations in statement positions.
TestLocalDoesNotThrow("if (true) var x;");
TestLocalDoesNotThrow("if (true) {} else var x;");
TestLocalDoesNotThrow("do var x; while (false)");
TestLocalDoesNotThrow("while (false) var x;");
TestLocalDoesNotThrow("label: var x;");
TestLocalDoesNotThrow("for (;false;) var x;");
TestLocalDoesNotThrow("switch (true) { case true: var x; }");
TestLocalDoesNotThrow("switch (true) { default: var x; }");

// Test class declarations with initialisers in statement positions.
TestLocalThrows("if (true) class x { };", SyntaxError);
TestLocalThrows("if (true) {} else class x { };", SyntaxError);
TestLocalThrows("do class x { }; while (false)", SyntaxError);
TestLocalThrows("while (false) class x { };", SyntaxError);
TestLocalThrows("label: class x { };", SyntaxError);
TestLocalThrows("for (;false;) class x { };", SyntaxError);
TestLocalDoesNotThrow("switch (true) { case true: class x { }; }");
TestLocalDoesNotThrow("switch (true) { default: class x { }; }");

// Test that redeclarations of functions are only allowed in outermost scope.
TestLocalThrows("{ let f; var f; }");
TestLocalThrows("{ var f; let f; }");
TestLocalThrows("{ function f() {} let f; }");
TestLocalThrows("{ let f; function f() {} }");
TestLocalThrows("{ function f() {} var f; }");
TestLocalThrows("{ var f; function f() {} }");
TestLocalThrows("{ function f() {} class f {} }");
TestLocalThrows("{ class f {}; function f() {} }");
TestLocalThrows("{ function f() {} function f() {} }");
TestLocalThrows("function f() {} let f;");
TestLocalThrows("let f; function f() {}");
TestLocalThrows("function f() {} class f {}");
TestLocalThrows("class f {}; function f() {}");
TestLocalDoesNotThrow("function arg() {}");
TestLocalDoesNotThrow("function f() {} var f;");
TestLocalDoesNotThrow("var f; function f() {}");
TestLocalDoesNotThrow("function f() {} function f() {}");

function g(f) {
  function f() { return 1 }
  return f()
}
assertEquals(1, g(function() { return 2 }))


// Test function declarations in source element and
// sloppy statement positions.
function f() {
  // Sloppy source element positions.
  function g0() {
    "use strict";
    // Strict source element positions.
    function h() { }
    {
      function h1() { }
    }
  }
  {
    function g1() { }
  }
}
f();

// Test function declarations in statement position in strict mode.
TestLocalThrows("function f() { if (true) function g() {} }", SyntaxError);
TestLocalThrows("function f() { if (true) {} else function g() {} }", SyntaxError);
TestLocalThrows("function f() { do function g() {} while (false) }", SyntaxError);
TestLocalThrows("function f() { while (false) function g() {} }", SyntaxError);
TestLocalThrows("function f() { label: function g() {} }", SyntaxError);
TestLocalThrows("function f() { for (;false;) function g() {} }", SyntaxError);
TestLocalDoesNotThrow("function f() { switch (true) { case true: function g() {} } }");
TestLocalDoesNotThrow("function f() { switch (true) { default: function g() {} } }");