Rustc-dev-guide: "Diagnostics: reporting errors and lints"

[nikomatsakis]

We should talk first about:

• Guidelines for emitting errors
  
  
  
  • How to find an error code and add an extended error
  
  
  • Conventions are how the error should be formatted (lowercase letter, etc)
    
    
    
    
    
    • link or maybe just inline the RFC with guidelines on how extended errors should look
    
    
    
  
  
  • when to use span_label etc
  
  
• How to emit lints
  
  
  
  • When to use a lint
  
  
  • If you have a tcx
  
  
  • Before you have a tcx
  
  
  • Some tips here at the end of Rustc bug fix procedure
  
  

EDIT(mark-i-m): See https://github.com/rust-lang/rustc-dev-guide/issues/14#issuecomment-514932385

cc @estebank

[Karrq]

Looks to me like this issue is currently missing the following:

Errors:

• How to find an error code and add an extended error
• Conventions are how the error should be formatted (lowercase letter, etc)
• when to use span_label etc

Lints:
Nothing? Maybe the section about removing lints present in the rustc Bug Fix Procedure could be added.

[phansch]

It might also be nice to link to the lint naming ~recommendations~ rules from RFC0344