Auto merge of #63779 - Centril:rollup-sx96dli, r=Centril

Auto merge of #63779 - Centril:rollup-sx96dli, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #63721 (Do not emit JSON dumps of diagnostic codes)
 - #63753 (Bump toml dependency.)
 - #63755 (Use dedicated type for spans in pre-expansion gating.)
 - #63759 (Allow 'default async fn' to parse.)
 - #63760 (Update books)
 - #63762 (`async_await` was stabilized in 1.39.0, not 1.38.0.)
 - #63766 (Remove some duplication when resolving constants)

Failed merges:

r? @ghost