Summary

On a github windows runner, I see an "access violation" error when building Decimal. It seems somewhat repeatable, and to affect ghc 8.8.3 but not 8.8.2.

Steps to reproduce

I don't have a local windows machine. Here is a github windows run with ghc 8.8.2 that succeeded: https://github.com/simonmichael/hledger/runs/512657680

Here is the same run with ghc 8.8.3, failing while building Decimal. The full raw log can be seen here for now. Here's the error:

2020-03-17T01:43:04.8072276Z Decimal> Configuring Decimal-0.5.1...
2020-03-17T01:43:05.4412135Z Decimal> 
2020-03-17T01:43:05.4495816Z Decimal> Access violation in generated code when writing 0x0
2020-03-17T01:43:05.5021471Z Decimal> 
2020-03-17T01:43:05.5022666Z Decimal>  Attempting to reconstruct a stack trace...
2020-03-17T01:43:05.5023008Z Decimal> 
2020-03-17T01:43:05.5023347Z Decimal>    Frame	Code address
2020-03-17T01:43:05.5023611Z Decimal>  * 0x461da80	0x37f7b66 C:\Users\runneradmin\AppData\Local\Programs\stack\x86_64-windows\ghc-8.8.3\bin\ghc.exe+0x33f7b66
2020-03-17T01:43:05.5023871Z Decimal>  * 0x461da88	0x3277bb9 C:\Users\runneradmin\AppData\Local\Programs\stack\x86_64-windows\ghc-8.8.3\bin\ghc.exe+0x2e77bb9
2020-03-17T01:43:05.5024123Z Decimal>  * 0x461da90	0x5
2020-03-17T01:43:05.5024457Z Decimal>  * 0x461da98	0x5
2020-03-17T01:43:05.5024708Z Decimal>  * 0x461daa0	0x3d7dc22 C:\Users\runneradmin\AppData\Local\Programs\stack\x86_64-windows\ghc-8.8.3\bin\ghc.exe+0x397dc22
2020-03-17T01:43:05.5025071Z Decimal>  * 0x461daa8	0x6308330
2020-03-17T01:43:05.5026895Z Decimal> 

It seems to fail the same way at the same place on every run of this (hledger CI) workflow with ghc 8.8.3, and never fails with ghc 8.8.2.

https://github.com/simonmichael/ghc-Decimal-test/actions is a simpler workflow based on the above which just builds Decimal; this one doesn't reproduce the issue.

Expected behavior

Build Decimal successfully.

Environment

GHC 8.8.3, invoked via stack 2.1.3.

Optional:

Windows Server 2019 ("windows-latest" in github actions).