gopherjs / gopherjs/gopherjs

math.MaxFloat32 converted to int64 incorrectly:

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bug
Dominant language
Go
Stars
13.2k
Forks
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PR merge metrics
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Description

package main

import (
	"fmt"
	"math"
)

func main() {
	var f float32 = math.MaxFloat32
	fmt.Printf("Hello, playground: %x\n", int64(float32(f)))
}

Go output: -8000000000000000

GopherJS output: 0

https://gopherjs.github.io/playground/#/2uCovf4ywh
https://go.dev/play/p/m7yL_crK_Qb

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the issue's Go reproducer and comparing the native Go and GopherJS outputs for converting math.MaxFloat32 to int64. Trace the compiler's float32-to-int64 conversion path; done means GopherJS produces the same result as Go for this case.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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