Add TypeFeasiblySubsumesType cache for individual compiler runs

Author: vzarytovskii

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -10,10 +10,11 @@
 * Fix nullness inference for member val and other OO scenarios  ([PR #17845](https://github.com/dotnet/fsharp/pull/17845))
 * Fix internal error when analyzing incomplete inherit member ([PR #17905](https://github.com/dotnet/fsharp/pull/17905))
 
-
 ### Added
+
 * Deprecate places where `seq` can be omitted. ([Language suggestion #1033](https://github.com/fsharp/fslang-suggestions/issues/1033), [PR #17772](https://github.com/dotnet/fsharp/pull/17772))
 * Support literal attribute on decimals ([PR #17769](https://github.com/dotnet/fsharp/pull/17769))
+* Added type conversions cache, only enabled for compiler runs, guarded by language version preview ([PR#17668](https://github.com/dotnet/fsharp/pull/17668))
 
 ### Changed
 

docs/release-notes/.Language/preview.md

@@ -2,6 +2,7 @@
 
 * Better generic unmanaged structs handling. ([Language suggestion #692](https://github.com/fsharp/fslang-suggestions/issues/692), [PR #12154](https://github.com/dotnet/fsharp/pull/12154))
 * Deprecate places where `seq` can be omitted. ([Language suggestion #1033](https://github.com/fsharp/fslang-suggestions/issues/1033), [PR #17772](https://github.com/dotnet/fsharp/pull/17772))
+* Added type conversions cache, only enabled for compiler runs ([PR#17668](https://github.com/dotnet/fsharp/pull/17668))
 
 ### Fixed
 

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -43,6 +43,7 @@ open FSharp.Compiler.TypedTreeBasics
 open FSharp.Compiler.TypedTreeOps
 open FSharp.Compiler.TypeHierarchy
 open FSharp.Compiler.TypeRelations
+open Import
 
 #if !NO_TYPEPROVIDERS
 open FSharp.Compiler.TypeProviders

src/Compiler/Checking/InfoReader.fs

@@ -24,6 +24,7 @@ open FSharp.Compiler.TypedTreeOps
 open FSharp.Compiler.TypedTreeBasics
 open FSharp.Compiler.TypeHierarchy
 open FSharp.Compiler.TypeRelations
+open Import
 
 /// Use the given function to select some of the member values from the members of an F# type
 let SelectImmediateMemberVals g optFilter f withExplicitImpl (tcref: TyconRef) = 

src/Compiler/Checking/MethodOverrides.fs

@@ -107,6 +107,7 @@ exception TypeIsImplicitlyAbstract of range
 exception OverrideDoesntOverride of DisplayEnv * OverrideInfo * MethInfo option * TcGlobals * Import.ImportMap * range
 
 module DispatchSlotChecking =
+    open Import
 
     /// Print the signature of an override to a buffer as part of an error message
     let PrintOverrideToBuffer denv os (Override(_, _, id, methTypars, memberToParentInst, argTys, retTy, _, _, _)) = 

src/Compiler/Checking/NicePrint.fs

@@ -2045,7 +2045,7 @@ module TastDefinitionPrinting =
                 (not vref.IsCompilerGenerated) &&
                 (denv.showObsoleteMembers || not (CheckFSharpAttributesForObsolete denv.g vref.Attribs)) &&
                 (denv.showHiddenMembers || not (CheckFSharpAttributesForHidden denv.g vref.Attribs))
-                
+
         let ctors =
             GetIntrinsicConstructorInfosOfType infoReader m ty
             |> List.filter (fun minfo -> IsMethInfoAccessible amap m ad minfo && not minfo.IsClassConstructor && shouldShow minfo.ArbitraryValRef)
@@ -2057,7 +2057,7 @@ module TastDefinitionPrinting =
                 tycon.ImmediateInterfacesOfFSharpTycon
                 |> List.filter (fun (_, compgen, _) -> not compgen)
                 |> List.map p13
-            else 
+            else
                 GetImmediateInterfacesOfType SkipUnrefInterfaces.Yes g amap m ty
 
         let iimplsLs =

src/Compiler/Checking/PatternMatchCompilation.fs

@@ -24,6 +24,7 @@ open FSharp.Compiler.TypedTreeOps
 open FSharp.Compiler.TypedTreeOps.DebugPrint
 open FSharp.Compiler.TypeRelations
 open type System.MemoryExtensions
+open Import
 
 exception MatchIncomplete of bool * (string * bool) option * range
 exception RuleNeverMatched of range