LDM 2024 07 15 Usage Data

Building a large internal repo with this.field/value style of breaking changes had 100+ errors. Hit every variation of the diagnostic:

• field as field
• value as field
• this.that.value in accessor

Example:

public int Value
{
  get { return this.value; }
  set
  {
    this.value = value;
    this.valuePtr = &value;
  }
}

Random repos found with GH queries

• this.value 209K results, 20% hit rate of real bug through 2 pages
  • https://github.com/DotNetAnalyzers/StyleCopAnalyzers
  • https://github.com/VodeoGames/VodeoECS
  • https://github.com/NeoforceControls/Neoforce-Mono
  • https://github.com/askeladdk/aiedit
  • https://github.com/YuhangGe/DLX-System
  • https://github.com/GameDiffs/TheForest
  • https://github.com/alexsteb/GuitarPro-to-Midi
• this.that.value 106K results, 8% hit rate of real bug through 4 pages
  • https://github.com/Real-Serious-Games/Unity-Editor-UI
  • https://github.com/VeeamHub/SuperEdit
  • https://github.com/moto2002/mobahero_src
• this.field 41K results, 8% hit rate of real bugs through 3 pages
  • https://github.com/HaloMods/Halo1AnimationEditor
  • https://github.com/Team-COCONUT/Minotaur
  • https://github.com/moto2002/mobahero_src
  • https://github.com/Toskyuu/TPW
  • https://github.com/graehu/SON

I only dug in the first 4-5 pages for each query as I felt it was representative at that point. Possible I'm wrong but I doubt the numbers would change if we dug any deeper.

More GH queries:

• _field as a field name. 6K results, near 100% hit rate
• _value as a field name. 137K results, near 100% hit rate

Largest intentional breaking change we've in last ~5 years was lambda inference and overload changes:

• Had a very long lead and got plenty of preview feedback about it.
• In total we had ~20-30 bugs filed against it.
• That is number of customers who did not self correct. Let's assume for sake of argument that total number of users that hit this problem is 10x reported. So 200-300

My conclusions from data:

1. Generated code is a challenge for our fixer
2. field and _field are uncommon but not rare field names
   • The use of field/_field is a style decision
   • Breaking change is about the style in which it is declared and accessed: this.field = vs. field =
3. value and _value are common field names
   • The use of value/_value is a style decision
   • Breaking change is about the style in which it is declared and accessed: this.value vs. value =
4. Ratio of field:value virtually every query is 1:8-1:12
5. Breaks on this.value or this.field are not viable
   • In the range of 20K and 10K impacted GH samples
   • That is roughly 2 orders of magnitude greater than the upper bound of our highest breaking change
6. It is very hard to quantify what the breaks on naked field / value would be.
   • Hard to construct a GH query to narrow down to uses of field / value without keywords.
   • Metadata queries can't distinguish between this.field and simply field in an accessor