Changelog #305

#21218 bump minimum supported toolchain version from 1.78 to 1.90.

#21205 (first contribution) handle #[cfg] in macro input attribute stripping.

#21203 add configuration option to hide placeholder type hints.

#21222 don’t complete unit return type in async associated items.

#21215 don’t implement sizedness check via all_field_tys.

#21190, #21195 more proc macro server fixes.

#21223 temporarily disable postcard.

#21198 add missing semicolon in incomplete let completion.

#21183 register define_opaque built-in attribute macro.

#21164 allow multiple active discovery operations.

#21182 remove TraitEnvironment.

#21178 make ModuleId and BlockLoc tracked structs.

#21208 handle lint attribute expansion in hir.

#21188 fix rustdoc warnings and enable them on CI.

#21189 remove mdbook-toc usage from the book.