Rollup v1.19.4 freezes when trying to bundle our frontend app

[mvila]

• Rollup Version: v1.19.4
• Operating System (or Browser): macOS 10.14.6
• Node Version: v10.16.2

How Do We Reproduce?

I am sorry but I couldn't find a way to reproduce the issue with a minimal code sample. The issue is occurring when we try to bundle one of our frontend app, which is quite big.

Expected Behavior

Successfully bundling our app.

Actual Behavior

Rollup v1.19.4 freezes until I kill the process. It seems it is stuck in an infinite loop.

There are no issues using the previous version of Rollup (v1.19.3).

I had a look at the recent commits, and I am not sure it can help, but this function smells suspicious to me:

rollup/src/utils/renderHelpers.ts

Line 169 in 9879cbc

export function removeLineBreaks(code: MagicString, start: number, end: number) {

[lukastaegert]

This is possible but does not seem too likely to me. Did your app bundle with earlier versions since 1.0.0? I so, can you pinpoint the first version that fails? Beyond this, we would need to debug at what stage it hangs.

[cadrimiranda]

My rollup is freezing too. I start the compilation and doesn't finish. I don't know why this happen and do not have a sample to show, because is a large project.

[cadrimiranda]

I tried install some old versions of rollup and the only versions that works is 1.18.0 and the oldest's.

[mvila]

@lukastaegert Our app could successfully bundle with the previous version of Rollup (v1.19.3).

Actually, the issue seems to be located in the findFirstLineBreakOutsideComment() function:

rollup/src/utils/renderHelpers.ts

Line 50 in 9879cbc

export function findFirstLineBreakOutsideComment(code: string, start = 0) {

I added a counter in the while (true) loop, and I could count more than 5,000,000,000 iterations before I got bored and killed the process.

Here is the input code that leads to the infinite loop:

import * as commonjsHelpers from 'commonjsHelpers.js';

var dist = commonjsHelpers.createCommonjsModule(function (module) {
module.exports=function(t){function n(e){if(r[e])return r[e].exports;var o=r[e]={i:e,l:!1,exports:{}};return t[e].call(o.exports,o,o.exports,n),o.l=!0,o.exports}var r={};return n.m=t,n.c=r,n.d=function(t,r,e){n.o(t,r)||Object.defineProperty(t,r,{configurable:!1,enumerable:!0,get:e})},n.n=function(t){var r=t&&t.__esModule?function(){return t.default}:function(){return t};return n.d(r,"a",r),r},n.o=function(t,n){return Object.prototype.hasOwnProperty.call(t,n)},n.p="",n(n.s=13)}([function(t,n){var r=t.exports="undefined"!=typeof window&&window.Math==Math?window:"undefined"!=typeof self&&self.Math==Math?self:Function("return this")();"number"==typeof __g&&(__g=r)},function(t,n){t.exports=function(t){return"object"==typeof t?null!==t:"function"==typeof t}},function(t,n){var r=t.exports={version:"2.5.0"};"number"==typeof __e&&(__e=r)},function(t,n,r){t.exports=!r(4)(function(){return 7!=Object.defineProperty({},"a",{get:function(){return 7}}).a})},function(t,n){t.exports=function(t){try{return!!t()}catch(t){return!0}}},function(t,n){var r={}.toString;t.exports=function(t){return r.call(t).slice(8,-1)}},function(t,n,r){var e=r(32)("wks"),o=r(9),i=r(0).Symbol,u="function"==typeof i;(t.exports=function(t){return e[t]||(e[t]=u&&i[t]||(u?i:o)("Symbol."+t))}).store=e},function(t,n,r){var e=r(0),o=r(2),i=r(8),u=r(22),c=r(10),f=function(t,n,r){var a,s,p,l,v=t&f.F,y=t&f.G,h=t&f.S,d=t&f.P,x=t&f.B,g=y?e:h?e[n]||(e[n]={}):(e[n]||{}).prototype,m=y?o:o[n]||(o[n]={}),b=m.prototype||(m.prototype={});y&&(r=n);for(a in r)s=!v&&g&&void 0!==g[a],p=(s?g:r)[a],l=x&&s?c(p,e):d&&"function"==typeof p?c(Function.call,p):p,g&&u(g,a,p,t&f.U),m[a]!=p&&i(m,a,l),d&&b[a]!=p&&(b[a]=p)};e.core=o,f.F=1,f.G=2,f.S=4,f.P=8,f.B=16,f.W=32,f.U=64,f.R=128,t.exports=f},function(t,n,r){var e=r(16),o=r(21);t.exports=r(3)?function(t,n,r){return e.f(t,n,o(1,r))}:function(t,n,r){return t[n]=r,t}},function(t,n){var r=0,e=Math.random();t.exports=function(t){return"Symbol(".concat(void 0===t?"":t,")_",(++r+e).toString(36))}},function(t,n,r){var e=r(24);t.exports=function(t,n,r){if(e(t),void 0===n)return t;switch(r){case 1:return function(r){return t.call(n,r)};case 2:return function(r,e){return t.call(n,r,e)};case 3:return function(r,e,o){return t.call(n,r,e,o)}}return function(){return t.apply(n,arguments)}}},function(t,n){t.exports=function(t){if(void 0==t)throw TypeError("Can't call method on  "+t);return t}},function(t,n,r){var e=r(28),o=Math.min;t.exports=function(t){return t>0?o(e(t),9007199254740991):0}},function(t,n,r){"use strict";n.__esModule=!0,n.default=function(t,n){if(t&&n){var r=Array.isArray(n)?n:n.split(","),e=t.name||"",o=t.type||"",i=o.replace(/\/.*$/,"");return r.some(function(t){var n=t.trim();return"."===n.charAt(0)?e.toLowerCase().endsWith(n.toLowerCase()):n.endsWith("/*")?i===n.replace(/\/.*$/,""):o===n})}return!0},r(14),r(34)},function(t,n,r){r(15),t.exports=r(2).Array.some},function(t,n,r){"use strict";var e=r(7),o=r(25)(3);e(e.P+e.F*!r(33)([].some,!0),"Array",{some:function(t){return o(this,t,arguments[1])}})},function(t,n,r){var e=r(17),o=r(18),i=r(20),u=Object.defineProperty;n.f=r(3)?Object.defineProperty:function(t,n,r){if(e(t),n=i(n,!0),e(r),o)try{return u(t,n,r)}catch(t){}if("get"in r||"set"in r)throw TypeError("Accessors not supported!");return"value"in r&&(t[n]=r.value),t}},function(t,n,r){var e=r(1);t.exports=function(t){if(!e(t))throw TypeError(t+" is not an object!");return t}},function(t,n,r){t.exports=!r(3)&&!r(4)(function(){return 7!=Object.defineProperty(r(19)("div"),"a",{get:function(){return 7}}).a})},function(t,n,r){var e=r(1),o=r(0).document,i=e(o)&&e(o.createElement);t.exports=function(t){return i?o.createElement(t):{}}},function(t,n,r){var e=r(1);t.exports=function(t,n){if(!e(t))return t;var r,o;if(n&&"function"==typeof(r=t.toString)&&!e(o=r.call(t)))return o;if("function"==typeof(r=t.valueOf)&&!e(o=r.call(t)))return o;if(!n&&"function"==typeof(r=t.toString)&&!e(o=r.call(t)))return o;throw TypeError("Can't convert object to primitive value")}},function(t,n){t.exports=function(t,n){return{enumerable:!(1&t),configurable:!(2&t),writable:!(4&t),value:n}}},function(t,n,r){var e=r(0),o=r(8),i=r(23),u=r(9)("src"),c=Function.toString,f=(""+c).split("toString");r(2).inspectSource=function(t){return c.call(t)},(t.exports=function(t,n,r,c){var a="function"==typeof r;a&&(i(r,"name")||o(r,"name",n)),t[n]!==r&&(a&&(i(r,u)||o(r,u,t[n]?""+t[n]:f.join(String(n)))),t===e?t[n]=r:c?t[n]?t[n]=r:o(t,n,r):(delete t[n],o(t,n,r)))})(Function.prototype,"toString",function(){return"function"==typeof this&&this[u]||c.call(this)})},function(t,n){var r={}.hasOwnProperty;t.exports=function(t,n){return r.call(t,n)}},function(t,n){t.exports=function(t){if("function"!=typeof t)throw TypeError(t+" is not a function!");return t}},function(t,n,r){var e=r(10),o=r(26),i=r(27),u=r(12),c=r(29);t.exports=function(t,n){var r=1==t,f=2==t,a=3==t,s=4==t,p=6==t,l=5==t||p,v=n||c;return function(n,c,y){for(var h,d,x=i(n),g=o(x),m=e(c,y,3),b=u(g.length),_=0,w=r?v(n,b):f?v(n,0):void 0;b>_;_++)if((l||_ in g)&&(h=g[_],d=m(h,_,x),t))if(r)w[_]=d;else if(d)switch(t){case 3:return!0;case 5:return h;case 6:return _;case 2:w.push(h)}else if(s)return!1;return p?-1:a||s?s:w}}},function(t,n,r){var e=r(5);t.exports=Object("z").propertyIsEnumerable(0)?Object:function(t){return"String"==e(t)?t.split(""):Object(t)}},function(t,n,r){var e=r(11);t.exports=function(t){return Object(e(t))}},function(t,n){var r=Math.ceil,e=Math.floor;t.exports=function(t){return isNaN(t=+t)?0:(t>0?e:r)(t)}},function(t,n,r){var e=r(30);t.exports=function(t,n){return new(e(t))(n)}},function(t,n,r){var e=r(1),o=r(31),i=r(6)("species");t.exports=function(t){var n;return o(t)&&(n=t.constructor,"function"!=typeof n||n!==Array&&!o(n.prototype)||(n=void 0),e(n)&&null===(n=n[i])&&(n=void 0)),void 0===n?Array:n}},function(t,n,r){var e=r(5);t.exports=Array.isArray||function(t){return"Array"==e(t)}},function(t,n,r){var e=r(0),o=e["__core-js_shared__"]||(e["__core-js_shared__"]={});t.exports=function(t){return o[t]||(o[t]={})}},function(t,n,r){"use strict";var e=r(4);t.exports=function(t,n){return!!t&&e(function(){n?t.call(null,function(){},1):t.call(null)})}},function(t,n,r){r(35),t.exports=r(2).String.endsWith},function(t,n,r){"use strict";var e=r(7),o=r(12),i=r(36),u="".endsWith;e(e.P+e.F*r(38)("endsWith"),"String",{endsWith:function(t){var n=i(this,t,"endsWith"),r=arguments.length>1?arguments[1]:void 0,e=o(n.length),c=void 0===r?e:Math.min(o(r),e),f=String(t);return u?u.call(n,f,c):n.slice(c-f.length,c)===f}})},function(t,n,r){var e=r(37),o=r(11);t.exports=function(t,n,r){if(e(n))throw TypeError("String#"+r+" doesn't accept regex!");return String(o(t))}},function(t,n,r){var e=r(1),o=r(5),i=r(6)("match");t.exports=function(t){var n;return e(t)&&(void 0!==(n=t[i])?!!n:"RegExp"==o(t))}},function(t,n,r){var e=r(6)("match");t.exports=function(t){var n=/./;try{"/./"[t](n)}catch(r){try{return n[e]=!1,!"/./"[t](n)}catch(t){}}return!0}}]);
});

export default commonjsHelpers.unwrapExports(dist);
export { dist as __moduleExports };

[lukastaegert]

@mvila Thanks a lot, this looks very helpful! I fear I will not find more time to debug today but will have a look first thing tomorrow.

[lukastaegert]

Thanks to your help I was able to understand what went wrong, fix is upcoming. The thing is, the function findFirstLineBreakOutsideComment has the hidden assumption that the scanned string does not contain /* or // except when a comment starts. In your case, the sample contains the string "/*" which was falsely interpreted as a comment start, but of course there was no corresponding comment end.

With the previous usages, this was not a problem as the string was sliced before passing it to the function so that it could only contain whitespace and comments, but for the latest addition removeLineBreaks I forgot this hidden assumption, so the fix will also add this assumption as a comment 🙄

Minimal repro: https://rollupjs.org/repl/?version=1.19.4&shareable=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

(remove coment to trigger issue)

[lukastaegert]

Fix at #3069

[mvila]

@lukastaegert Thanks a lot for this quick fix! 😄