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while loop + break compilation bug #39

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Open
while loop + break compilation bug#39

Description

@elisee
elisee
opened on May 5, 2014

I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:

function a() end
while true do
break
end

This gets compiled to:

G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).

The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.

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      , 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
       blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
      Skip to content
      while loop + break compilation bug #39
      Open
      Open
      while loop + break compilation bug#39
      Description
      @elisee
      elisee
      opened on May 5, 2014
      I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
      function a() end
while true do
break
end

      This gets compiled to:
      G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

      Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
      The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
          Skip to content
          while loop + break compilation bug #39
          Open
          Open
          while loop + break compilation bug#39
          Description
          @elisee
          elisee
          opened on May 5, 2014
          I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
          function a() end
while true do
break
end

          This gets compiled to:
          G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

          Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
          The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
          Metadata
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          No one assigned
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              None yet
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              No branches or pull requests
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
              Skip to content
              while loop + break compilation bug #39
              Open
              Open
              while loop + break compilation bug#39
              Description
              @elisee
              elisee
              opened on May 5, 2014
              I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
              function a() end
while true do
break
end

              This gets compiled to:
              G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

              Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
              The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
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                  No branches or pull requests
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
                  Skip to content
                  while loop + break compilation bug #39
                  Open
                  Open
                  while loop + break compilation bug#39
                  Description
                  @elisee
                  elisee
                  opened on May 5, 2014
                  I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
                  function a() end
while true do
break
end

                  This gets compiled to:
                  G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

                  Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
                  The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
                  Metadata
                  Metadata
                  Assignees
                  No one assigned
                    Labels
                    No labels
                    No labels
                    Projects
                    No projects
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                      No milestone
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                      None yet
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                      No branches or pull requests
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
                      Skip to content
                      while loop + break compilation bug #39
                      Open
                      Open
                      while loop + break compilation bug#39
                      Description
                      @elisee
                      elisee
                      opened on May 5, 2014
                      I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
                      function a() end
while true do
break
end

                      This gets compiled to:
                      G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

                      Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
                      The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
                      Metadata
                      Metadata
                      Assignees
                      No one assigned
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                        No labels
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                        No projects
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                          No milestone
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                          None yet
                          Development
                          No branches or pull requests
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
                          Skip to content
                          while loop + break compilation bug #39
                          Open
                          Open
                          while loop + break compilation bug#39
                          Description
                          @elisee
                          elisee
                          opened on May 5, 2014
                          I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
                          function a() end
while true do
break
end

                          This gets compiled to:
                          G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

                          Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
                          The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
                          Metadata
                          Metadata
                          Assignees
                          No one assigned
                            Labels
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                            No labels
                            Projects
                            No projects
                              Milestone
                              No milestone
                              Relationships
                              None yet
                              Development
                              No branches or pull requests
                              Issue actions
                              
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
while loop + break compilation bug · Issue #39 · mherkender/lua.js · GitHub
                              Skip to content
                              while loop + break compilation bug #39
                              Open
                              Open
                              while loop + break compilation bug#39
                              Description
                              @elisee
                              elisee
                              opened on May 5, 2014
                              I encountered this bug while compiling to JS real-life Lua. This minimal code triggers it:
                              function a() end
while true do
break
end

                              This gets compiled to:
                              G.str['a'] = (function () {
var tmp;
return [];
})
while (true) (function() {
return;
})();

                              Notice the immediately-invoked function expression (IIFE) inside the while loop in the generated JS code. The Lua break statement is compiled into a return call but all it does is leave the function body, not the loop. So the loop, which should exit immediately, runs forever (and locks up the browser).
                              The Lua function declaration function a() end at the top is required to trigger the insertion of the IIFE and thus the bug.
                              Metadata
                              Metadata
                              Assignees
                              No one assigned
                                Labels
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                                No labels
                                Projects
                                No projects
                                  Milestone
                                  No milestone
                                  Relationships
                                  None yet
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                                  No branches or pull requests
                                  Issue actions