Expose missing constraints

Author: ncave

src/Compiler/Symbols/Symbols.fs

@@ -1596,6 +1596,11 @@ type FSharpGenericParameterConstraint(cenv, cx: TyparConstraint) =
         | TyparConstraint.IsDelegate(ty1, ty2, _) ->  FSharpGenericParameterDelegateConstraint(cenv, ty1, ty2) 
         | _ -> invalidOp "not a delegate constraint"
 
+    member _.AllowsRefStruct = 
+        match cx with 
+        | TyparConstraint.AllowsRefStruct _ -> true 
+        | _ -> false
+
     override x.ToString() = "<type constraint>"
 
 type FSharpInlineAnnotation = 

src/Compiler/Symbols/Symbols.fsi

@@ -708,6 +708,9 @@ type FSharpGenericParameterConstraint =
     /// Indicates a constraint that a type has a 'null' value
     member IsSupportsNullConstraint: bool
 
+    /// Indicates a constraint that a type doesn't support nullness
+    member IsNotSupportsNullConstraint: bool
+
     /// Indicates a constraint that a type supports F# generic comparison
     member IsComparisonConstraint: bool
 
@@ -750,6 +753,9 @@ type FSharpGenericParameterConstraint =
     /// Gets further information about a delegate constraint
     member DelegateConstraintData: FSharpGenericParameterDelegateConstraint
 
+    /// An anti-constraint indicating that ref structs (e.g. Span<>) are allowed here
+    member AllowsRefStruct: bool
+
 [<RequireQualifiedAccess>]
 type FSharpInlineAnnotation =