Benefits

✅ Improved static analysis
✅ Improved type inference
✅ Increased type coverage

Highlights

• Typing of arrays
• Typing of closures
• Using constants, union string literals, and class-string instead of wider primitive types where possible
• Using generics to determine return types

Approach

• Many types are inferred from usage
• Some types are taken from the Symfony code base when classes extended or wrapped Symfony