start on @nogc
fix Issue 8373 - IFTI fails on overloading of function vs non function template
fix Issue 12591 - std/typecons.d(440): Error: tuple has no effect in expression
Fix Issue 12598 - Emit better diagnostics when type is found where an lvalue was expected.
Merge pull request #3459 from 9rnsr/fix8373

Issue 8373 - IFTI fails on overloading of function vs non function template
Merge pull request #3468 from 9rnsr/fix12591

[REG2.064] Issue 12591 - std/typecons.d(440): Error: tuple has no effect in expression
Merge pull request #3470 from AndrejMitrovic/Fix12598

Issue 12598 - Emit better diagnostics when type is found where an lvalue was expected
Fix Issue 12480 - Implement better static assert diagnostics by doing CTFE interpretation when optimizing static immutable arrays.
Merge pull request #3474 from AndrejMitrovic/Fix12480

Issue 12480 - Implement better static assert diagnostics for static immutable arrays.
Merge pull request #3455 from WalterBright/atnogc

start on @nogc
fix Issue 12604 - No "mismatched array lengths" error with narrowing conversions
fix Issue 12593 - AA cannot have struct as key
fix Issue 12602 - [CTFE] Changes to an array slice wrapped in a struct do not propogate to the original
fix Issue 11535 - CTFE ICE on reassigning a static array initialized with block assignment
fix Issue 12110 - [CTFE] Error: CTFE internal error: Dotvar assignment
Merge pull request #3475 from 9rnsr/fix12604

Issue 12604 - No "mismatched array lengths" error with narrowing conversions
Merge pull request #3480 from 9rnsr/fix12110

Issue 12110 - [CTFE] Error: CTFE internal error: Dotvar assignment
Merge pull request #3479 from 9rnsr/fix11535

Issue 11535 - CTFE ICE on reassigning a static array initialized with block assignment
Merge pull request #3478 from 9rnsr/fix12602

Issue 12602 - [CTFE] Changes to an array slice wrapped in a struct do not propogate to the original
Do not mark mutable parameters as STCin for internal library calls