fix Issue 13225 - [ICE] Access violation on invalid mixin template instantiation
Remove redundant error
fix Issue 13245 - segfault when instantiating template with non-compiling function literal
Merge pull request #3840 from 9rnsr/fix13225

Issue 13225 - [ICE] Access violation on invalid mixin template instantiation
fix Issue 13237 Wrong code with -inline -O
Merge pull request #3848 from WalterBright/fix13237

fix Issue 13237 Wrong code with -inline -O
[Refactoring] Remove unused methods appendExp and appendState
[Refactoring] Remove unused fields