<p dir="auto"><strong>I'm submitting a bug report</strong></p>
<p dir="auto"><strong>Webpack version:</strong><br>
2.x, 2.1.0-beta.20, from master (as of <a class="commit-link" data-hovercard-type="commit" data-hovercard-url="https://github.com/webpack/webpack/commit/2553f4931d01bda54d696092d73e3cba9e2e9b3b/hovercard" href="https://github.com/webpack/webpack/commit/2553f4931d01bda54d696092d73e3cba9e2e9b3b"><tt>2553f49</tt></a>)</p>
<p dir="auto"><strong>Please tell us about your environment:</strong><br>
OSX 10.x</p>
<p dir="auto"><strong>Current behavior:</strong><br>
Warnings like:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="WARNING in ./index.js
9:12 export 'x' was not found in './dep.js'"><pre class="notranslate"><code class="notranslate">WARNING in ./index.js
9:12 export 'x' was not found in './dep.js'
</code></pre></div>
<p dir="auto">duplicated multiple times on each rebuild in watch mode.</p>
<p dir="auto"><strong>Expected/desired behavior:</strong><br>
Warnings should be reported only once per occurrence.</p>
<p dir="auto"><strong>Repro</strong></p>
<p dir="auto">See <a href="https://github.com/andreypopp/wp2-stats-issue">https://github.com/andreypopp/wp2-stats-issue</a></p>
<p dir="auto">Sorry for duplicate issues but I'm really unsure what repo this issue belongs in. <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="133377396" data-permission-text="Title is private" data-url="https://github.com/webpack-contrib/eslint-loader/issues/80" data-hovercard-type="issue" data-hovercard-url="/webpack-contrib/eslint-loader/issues/80/hovercard" href="https://github.com/webpack-contrib/eslint-loader/issues/80">webpack-contrib/eslint-loader#80</a>. Looking at the updated dependencies I'm guessing this is some sort of issue with <code class="notranslate">acorn</code> versions but I'm not sure?</p>
<p dir="auto">Webpack 2 has a dependency on <code class="notranslate">"acorn": "^2.4.0"</code>, and Eslint 2 has a dependency on <code class="notranslate">"espree": "^3.0.0"</code> which in turn has a dependency on <code class="notranslate">"acorn": "^2.7.0"</code>.</p>
<ul dir="auto">
<li>Webpack 2 =&gt; <code class="notranslate">"acorn": "^2.4.0"</code></li>
<li>Eslint 2 =&gt;  <code class="notranslate">"espree": "^3.0.0"</code> =&gt; <code class="notranslate">"acorn": "^2.7.0"</code></li>
</ul>
<p dir="auto">Eslint 2 has a dependency on <code class="notranslate">"espree": "^2.2.4"</code> which in turn has NO <code class="notranslate">acorn</code> dependency so I'm guessing whatever is happening is some sort of conflict in <code class="notranslate">acorn</code> but I'm unsure how this plays out.</p>
<ul dir="auto">
<li>Webpack 2 =&gt; <code class="notranslate">"acorn": "^2.4.0"</code></li>
<li>Eslint 1 =&gt;  <code class="notranslate">"espree": "^2.2.4"</code></li>
</ul>
<p dir="auto">I think this could be an NPM 3 semver thing where NPM tries to be smart and and sees two versions of <code class="notranslate">acorn</code> with <code class="notranslate">^2.x</code> and extracts them out into the root of <code class="notranslate">node_modules</code></p>
<p dir="auto">Upon updating to Eslint 2 and Webpack 2 I get an error in <code class="notranslate">espree</code> shown below. With Webpack 1 I don't get this error, and with Webpack <code class="notranslate">2.0.7.-beta</code> and Eslint <code class="notranslate">1.x</code> I don't get the error as well. If you have any ideas and cold point me in the right direction I'd appreciate it.</p>
<div class="highlight highlight-source-json notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="{
  &quot;parser&quot;: &quot;babel-eslint&quot;,
  &quot;plugins&quot;: [
    &quot;react&quot;
  ],
  &quot;env&quot;: {
    &quot;browser&quot;: true,
    &quot;node&quot;: true
  },
  &quot;parserOptions&quot;: {
    &quot;ecmaVersion&quot;: 6,
    &quot;sourceType&quot;: &quot;module&quot;,
    &quot;ecmaFeatures&quot;: {
      &quot;arrowFunctions&quot;: true,
      &quot;blockBindings&quot;: true,
      &quot;experimentalObjectRestSpread&quot;: true,
      &quot;generators&quot;: true,
      &quot;jsx&quot;: true,
      &quot;module&quot;: true,
      &quot;modules&quot;: true,
      &quot;restParams&quot;: true,
      &quot;spread&quot;: true,
      &quot;jsx&quot;: true
    }
  }
}"><pre class="notranslate">{
  <span class="pl-ent">"parser"</span>: <span class="pl-s"><span class="pl-pds">"</span>babel-eslint<span class="pl-pds">"</span></span>,
  <span class="pl-ent">"plugins"</span>: [
    <span class="pl-s"><span class="pl-pds">"</span>react<span class="pl-pds">"</span></span>
  ],
  <span class="pl-ent">"env"</span>: {
    <span class="pl-ent">"browser"</span>: <span class="pl-c1">true</span>,
    <span class="pl-ent">"node"</span>: <span class="pl-c1">true</span>
  },
  <span class="pl-ent">"parserOptions"</span>: {
    <span class="pl-ent">"ecmaVersion"</span>: <span class="pl-c1">6</span>,
    <span class="pl-ent">"sourceType"</span>: <span class="pl-s"><span class="pl-pds">"</span>module<span class="pl-pds">"</span></span>,
    <span class="pl-ent">"ecmaFeatures"</span>: {
      <span class="pl-ent">"arrowFunctions"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"blockBindings"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"experimentalObjectRestSpread"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"generators"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"jsx"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"module"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"modules"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"restParams"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"spread"</span>: <span class="pl-c1">true</span>,
      <span class="pl-ent">"jsx"</span>: <span class="pl-c1">true</span>
    }
  }
}</pre></div>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="ERROR in ./src/js/index.js
Module parse failed: /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/babel-loader/index.js?{&quot;presets&quot;:[&quot;react&quot;,&quot;es2015&quot;,&quot;stage-0&quot;],&quot;plugins&quot;:[&quot;transform-runtime&quot;,&quot;transform-decorators-legacy&quot;,&quot;typecheck&quot;,[&quot;react-transform&quot;,{&quot;transforms&quot;:[{&quot;transform&quot;:&quot;react-transform-hmr&quot;,&quot;imports&quot;:[&quot;react&quot;],&quot;locals&quot;:[&quot;module&quot;]},{&quot;transform&quot;:&quot;react-transform-catch-errors&quot;,&quot;imports&quot;:[&quot;react&quot;,&quot;redbox-react&quot;]}]}]]}!/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/eslint-loader/index.js!/Users/davidfox-powell/dev/frontend-boilerplate/src/js/index.js 
Cannot read property 'ecmaFeatures' of undefined
You may need an appropriate loader to handle this file type.
TypeError: Cannot read property 'ecmaFeatures' of undefined
    at Parser.parseTopLevel (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/espree/espree.js:271:18)
    at Parser.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/acorn/dist/acorn.js:1636:17)
    at Object.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/acorn/dist/acorn.js:905:44)
    at Parser.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/Parser.js:960:18)
    at Module.&lt;anonymous&gt; (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/NormalModule.js:192:16)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/NormalModule.js:160:10
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:334:3
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:182:10)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:189:10)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:204:3
    at Object.context.callback (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:87:13)
    at Object.module.exports (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/babel-loader/index.js:89:8)
    at LOADER_EXECUTION (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:95:14)
    at runSyncOrAsync (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:96:4)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:200:2)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:189:10)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:204:3
    at Object.context.callback (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:87:13)
    at Object.module.exports (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/eslint-loader/index.js:113:8)
    at LOADER_EXECUTION (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:95:14)
    at runSyncOrAsync (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:96:4)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:200:2)
 @ multi main"><pre class="notranslate"><code class="notranslate">ERROR in ./src/js/index.js
Module parse failed: /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/babel-loader/index.js?{"presets":["react","es2015","stage-0"],"plugins":["transform-runtime","transform-decorators-legacy","typecheck",["react-transform",{"transforms":[{"transform":"react-transform-hmr","imports":["react"],"locals":["module"]},{"transform":"react-transform-catch-errors","imports":["react","redbox-react"]}]}]]}!/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/eslint-loader/index.js!/Users/davidfox-powell/dev/frontend-boilerplate/src/js/index.js 
Cannot read property 'ecmaFeatures' of undefined
You may need an appropriate loader to handle this file type.
TypeError: Cannot read property 'ecmaFeatures' of undefined
    at Parser.parseTopLevel (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/espree/espree.js:271:18)
    at Parser.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/acorn/dist/acorn.js:1636:17)
    at Object.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/acorn/dist/acorn.js:905:44)
    at Parser.parse (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/Parser.js:960:18)
    at Module.&lt;anonymous&gt; (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/NormalModule.js:192:16)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/webpack/lib/NormalModule.js:160:10
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:334:3
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:182:10)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:189:10)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:204:3
    at Object.context.callback (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:87:13)
    at Object.module.exports (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/babel-loader/index.js:89:8)
    at LOADER_EXECUTION (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:95:14)
    at runSyncOrAsync (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:96:4)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:200:2)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:189:10)
    at /Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:204:3
    at Object.context.callback (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:87:13)
    at Object.module.exports (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/eslint-loader/index.js:113:8)
    at LOADER_EXECUTION (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:95:14)
    at runSyncOrAsync (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:96:4)
    at iterateNormalLoaders (/Users/davidfox-powell/dev/frontend-boilerplate/node_modules/loader-runner/lib/LoaderRunner.js:200:2)
 @ multi main
</code></pre></div>