[Proposal] Error on ASI ambiguous cases #2130

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1. trusktr commented on Nov 17, 2021

   

   trusktr

   on Nov 17, 2021

   Last edited by trusktr

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   Just to clarify,

       return
       {}

   is always equivalent to return; which is different than the other example. Anything after a return statement without a semi colon never interacts with the return statement. But in the example

   let a = ambiguousAssignment
   [1].sort()

   the item on the next line does interact with the previous line.

   In my mind, there's no ambiguity with the return statement.

   I believe we should not error on these, but we should match JS syntax. People should learn the syntax.

   A warning might be ok, as long as it allows compilation of the program (with valid syntax) to complete.

   I write all my code without semi colons.
2. trusktr

   added

   enhancement

   on Nov 17, 2021
3. MaxGraey commented on Nov 17, 2021

   

   MaxGraey

   on Nov 17, 2021

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   I believe that any ambiguity that might create undefined behaviour or very different behaviour should produce an error. JS design especially as far as errors is concerned should be avoided altogether. JS is designed to execute in as many cases as possible and only throw a syntax error in the most extreme cases.
4. MaxGraey commented on Sep 1, 2022

   

   MaxGraey

   on Sep 1, 2022

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   More example:

   // nested call (without diagnostics errors)
   function b(x: () => void): () => void { return x }
   
   let value = b
   (() => console.log('Hello'))()
5. afederl commented on Oct 15, 2026

   

   afederl

   on Oct 15, 2026

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   Here is another example of unexpected behavior that may even be considered a bug:

           {
               let i: i32 = 3 
               let j: i32 = 45
               let k: i32 = 13
   
               i = j
               ++k
   
               console.log(`\n\n\nWITHOUT SEMICOLONS:  i = ${i}  j = ${j}  k = ${k}`)
           }
   
           {
               let i: i32 = 3;
               let j: i32 = 45;
               let k: i32 = 13;
   
               i = j;
               ++k;
   
               console.log(`\n\n\nWITH SEMICOLONS:     i = ${i}  j = ${j}  k = ${k}\n\n\n`);
           }

   Unlike JavaScript and TypeScript, AssemblyScript produces the following output:

   WITHOUT SEMICOLONS:  i = 45  j = 46  k = 13
   WITH SEMICOLONS:     i = 45  j = 45  k = 14

   In JavaScript and TypeScript, both versions produce the same output:

   WITHOUT SEMICOLONS:  i = 45  j = 45  k = 14
   WITH SEMICOLONS:     i = 45  j = 45  k = 14