v8/test/mjsunit/harmony/block-const-assign.js

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// Flags: --harmony-scoping

// Test that we throw early syntax errors in harmony mode
// when using an immutable binding in an assigment or with
// prefix/postfix decrement/increment operators.

"use strict";

// Function local const.
function constDecl0(use) {
  return "(function() { const constvar = 1; " + use + "; })();";
}


function constDecl1(use) {
  return "(function() { " + use + "; const constvar = 1; })();";
}


// Function local const, assign from eval.
function constDecl2(use) {
  use = "eval('(function() { " + use + " })')()";
  return "(function() { const constvar = 1; " + use + "; })();";
}


function constDecl3(use) {
  use = "eval('(function() { " + use + " })')()";
  return "(function() { " + use + "; const constvar = 1; })();";
}


// Block local const.
function constDecl4(use) {
  return "(function() { { const constvar = 1; " + use + "; } })();";
}


function constDecl5(use) {
  return "(function() { { " + use + "; const constvar = 1; } })();";
}


// Block local const, assign from eval.
function constDecl6(use) {
  use = "eval('(function() {" + use + "})')()";
  return "(function() { { const constvar = 1; " + use + "; } })();";
}


function constDecl7(use) {
  use = "eval('(function() {" + use + "})')()";
  return "(function() { { " + use + "; const constvar = 1; } })();";
}


// Function expression name.
function constDecl8(use) {
  return "(function constvar() { " + use + "; })();";
}


// Function expression name, assign from eval.
function constDecl9(use) {
  use = "eval('(function(){" + use + "})')()";
  return "(function constvar() { " + use + "; })();";
}

let decls = [ constDecl0,
              constDecl1,
              constDecl2,
              constDecl3,
              constDecl4,
              constDecl5,
              constDecl6,
              constDecl7,
              constDecl8,
              constDecl9
              ];
let declsForTDZ = new Set([constDecl1, constDecl3, constDecl5, constDecl7]);
let uses = [ 'constvar = 1;',
             'constvar += 1;',
             '++constvar;',
             'constvar++;'
             ];

function Test(d,u) {
  'use strict';
  try {
    print(d(u));
    eval(d(u));
  } catch (e) {
    if (declsForTDZ.has(d) && u !== uses[0]) {
      // In these cases, read of a const variable occurs
      // before a write to it, so TDZ kicks in before const check.
      assertInstanceof(e, ReferenceError);
      return;
    }
    assertInstanceof(e, TypeError);
    assertTrue(e.toString().indexOf("Assignment to constant variable") >= 0);
    return;
  }
  assertUnreachable();
}

for (var d = 0; d < decls.length; ++d) {
  for (var u = 0; u < uses.length; ++u) {
    Test(decls[d], uses[u]);
  }
}