minify() with enclose option appears to break source map #1333

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1. fabiosantoscode commented on Jan 19, 2023

   

   fabiosantoscode

   on Jan 19, 2023

   Collaborator

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   I can't reproduce with this call:

   console.log(await minify('let x = 1234; alert(x); alert(x); alert(x)', {
     enclose: true,
     sourceMap: true,
   }))

   {
     "code": "!function(){let t=1234;alert(t),alert(t),alert(t)}();",
     "map": "{\"version\":3,\"names\":[\"x\",\"alert\"],\"sources\":[null,\"0\"],\"mappings\":\"YCAA,IAAIA,EAAI,KAAMC,MAAMD,GAAIC,MAAMD,GAAIC,MAAMD,E\"}",
     "decoded_map": { ... }
   }
2. dqh-au commented on Jan 20, 2023

   

   dqh-au

   on Jan 20, 2023

   Author

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   This gets weirder and weirder. I think this might be an incompatibility between Terser's decoded_map and Rollup. minify() does indeed produce a source map for my test case, but Rollup does not seem to like it.

   Interestingly, your code snippet triggers the same problem when I place it in my source file.

   One thing I noticed is that our test cases share a map sources of [null, '0']. I haven't pinpointed the code yet, but I think the null source is resulting in an off by one error inside Rollup. Changing the source code input can result in a sources of ['0'], and when this happens Rollup emits a source map with content.

   Is a null source valid? I am new to this, but It does seem odd that a single source is producing two sources in the source map. I'm not sure what the right spec is, but https://sourcemaps.info/spec.html doesn't say anything about a null source.

   Another thing I noticed while testing is that the enclose option doesn't always result in wrapping the output in an life. For example:

   let result =
       await minify(
           'const log = console.log.bind(console); log("")',
           {
               enclose: true,
               sourceMap: true,
           });
   console.log(result.code);
   console.log('');
   console.log(result.map);
   

   outputs:

   console.log.bind(console)("");
   
   {"version":3,"names":["console","log","bind"],"sources":["0"],"mappings":"AAAYA,QAAQC,IAAIC,KAAKF,QAAUC,CAAI"}
   

   Whereas if I change the source to 'const log = console.log.bind(console); const warn = console.warn.bind(console); log("")', the output is:

   !function(){const o=console.log.bind(console);console.warn.bind(console);o("")}();
   
   {"version":3,"names":["log","console","bind","warn"],"sources":[null,"0"],"mappings":"YCAA,MAAMA,EAAMC,QAAQD,IAAIE,KAAKD,SAAuBA,QAAQE,KAAKD,KAAKD,SAAUD,EAAI,G"}
   

   👍React with 👍1Reacted by Tom Pereira