Merge branch 'master' into merge

rfcs/STATUS.md

@@ -8,6 +8,12 @@ This document tracks unimplemented RFCs.
 
 **Notes**: Implementing this RFC triggers warnings across the board in the apps ecosystem, in particular in testing libraries. Pending code changes / decisions.
 
+## Deprecate table.getn/foreach/foreachi
+
+[RFC: Deprecate table.getn/foreach/foreachi](https://github.com/Roblox/luau/blob/master/rfcs/deprecate-table-getn-foreach.md)
+
+**Status**: Needs implementation.
+
 ## Read-only and write-only properties
 
 [RFC: Read-only properties](https://github.com/Roblox/luau/blob/master/rfcs/property-readonly.md) |
@@ -15,14 +21,8 @@ This document tracks unimplemented RFCs.
 
 **Status**: Needs implementation
 
-## String interpolation
+## Expanded Subtyping for Generic Function Types
 
-[RFC: String interpolation](https://github.com/Roblox/luau/blob/master/rfcs/syntax-string-interpolation.md)
-
-**Status**: Needs implementation
-
-## Lower Bounds Calculation
-
-[RFC: Lower bounds calculation](https://github.com/Roblox/luau/blob/master/rfcs/lower-bounds-calculation.md)
+[RFC: Expanded Subtyping for Generic Function Types](https://github.com/Roblox/luau/blob/master/rfcs/generic-function-subtyping.md)
 
 **Status**: Implemented but not fully rolled out yet.

rfcs/deprecate-table-getn-foreach.md

@@ -0,0 +1,31 @@
+# Deprecate table.getn/foreach/foreachi
+
+## Summary
+
+Mark table.getn/foreach/foreachi as deprecated
+
+## Motivation
+
+`table.getn` was deprecated in Lua 5.1 that Luau is based on.
+
+`table.getn(x)` is equivalent to `rawlen(x)` when `x` is a table; when `x` is not a table, `table.getn` produces an error. It's difficult to imagine code where `table.getn(x)` is better than either `#x` (idiomatic) or `rawlen(x)` (fully compatible replacement). However, `table.getn` is slower and provides yet another way to perform an operation, leading new users of the language to use it unknowingly.
+
+`table.foreach` and `table.foreachi` were deprecated in Lua 5.2.
+
+`table.foreach` is equivalent to a `for .. pairs` loop; `table.foreachi` is equivalent to a `for .. ipairs` loop; both may also be replaced by generalized iteration. Both functions are significantly slower than equivalent `for` loop replacements, are more restrictive because the function can't yield, and result in new users (particularly coming from JS background) unknowingly using these thus producing non-idiomatic non-performant code.
+
+In both cases, the functions bring no value over other library or language alternatives, and thus just serve as a distraction.
+
+## Design
+
+We will mark all three functions as deprecated. The only consequence of this change is that the linter will start emitting warnings when they are used.
+
+Removing support for these functions doesn't provide any measurable value and as such is not planned in the foreseeable future because it may cause backwards compatibility issues.
+
+## Drawbacks
+
+None
+
+## Alternatives
+
+If we consider table.getn/etc as supported, we'd want to start optimizing their usage which gets particularly tricky with foreach and requires more compiler machinery than this is probably worth.

rfcs/lower-bounds-calculation.md

@@ -1,5 +1,7 @@
 # Lower Bounds Calculation
 
+**Status**: Abandoned in favor of a future design for full local inference
+
 ## Summary
 
 We propose adapting lower bounds calculation from Pierce's Local Type Inference paper into the Luau type inference algorithm.