Fixes

• (#6211, #6215) Class strings used in attributes were not properly qualified (@weirdan)
• (#6217, #6219) mb_str_split() signature was missing (@bitwise-operators)
• (#6231) Fixed language server crash on PHP 8 (@tm1000)
• (#6234, #6238) UnusedForeachValue was incorrectly flagged as fixable (@orklah)
• (#6234, #6244) date() now accepts null as timestamp when targeting PHP 8 (@masonmcelvain)
• (#3573, #6242) UnnecessaryVarAnnotation issuea are now suppressable (@orklah)
• (#6228, #6281, #6229) Prevented remote schema file download during config validation (@gmessier)
• (#4952, #6251) Psalm was outputting (incorrect) cached errors when error level was overridden with a cli parameter (@TysonAndre)
• (#6257, #6260) Psalm incorrectly assumed imagejpeg() to return string when path was specified as null (@MauricioFauth)
• (psalm/phar#9, #6267) psalm/phar releases were not created automatically (@weirdan)
• (#6261, #6272) Result of a sum of arrays was not inferred correctly, leading to possibly mixed keys (@orklah)
• (#5501, #6253) Some suppressions were incorrectly reported as unused (@orklah)
• (#6266, #6273) PHP_VERSION, DIRECTORY_SEPARATOR, PATH_SEPARATOR and PHP_EOL are now always considered non-empty (@VincentLanglet)
• (#6263, #6290) Psalm was incorrectly inferring result of splats in constant arrays (@weirdan)
• (#6289, #6290) Psalm was incorrectly inferring values for integer array keys in constant arrays (@weirdan)
• (#6220, #6233) in_array() now informs needle type based on haystack type (@supersmile2009)
• (#6268) Improved debug_backtrace() return type (@vudaltsov)
• (#6301, #6302) Phar-packaged language server did not analyze code on change (@thomasbley)
• (#3660, #6270) Psalm sometimes reported type coverage exceeding 100% (@muglug)

Internal changes

• (#6240) Literal arithmetic refactoring (@orklah)
• (#6252) Literal float methods for Union (@boesing)
• (#6247) Tests for callmap and deltas (@bitwise-operators)
• (#6279) Constant array inference refactoring (@weirdan)

Typos

• (#6248, #6291) @TysonAndre and @zonuexe fixed some typos