From 72ab794e5ef6506ff3a0d33c66fb48a0324aeac3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=A1=D0=BB=D0=B0=D0=B2=D0=B0=20=D0=A3=D0=BA=D1=80=D0=B0?=
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 <777696+ncave@users.noreply.github.com>
Date: Mon, 20 Jan 2025 10:33:51 +0000
Subject: [PATCH] Added missing type constraints in FCS (#18241)

* Expose missing constraints

* Updated release notes
---
 docs/release-notes/.FSharp.Compiler.Service/9.0.300.md      | 1 +
 src/Compiler/Symbols/Symbols.fs                             | 5 +++++
 src/Compiler/Symbols/Symbols.fsi                            | 6 ++++++
 ...arp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl | 4 ++++
 ...p.Compiler.Service.SurfaceArea.netstandard20.release.bsl | 4 ++++
 ...lverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl | 2 +-
 ...erify_FSharp.Compiler.Service_Release_netstandard2.0.bsl | 2 +-
 7 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/docs/release-notes/.FSharp.Compiler.Service/9.0.300.md b/docs/release-notes/.FSharp.Compiler.Service/9.0.300.md
index 66888c7cebe..5997ca29bd4 100644
--- a/docs/release-notes/.FSharp.Compiler.Service/9.0.300.md
+++ b/docs/release-notes/.FSharp.Compiler.Service/9.0.300.md
@@ -5,6 +5,7 @@
 
 ### Added
 
+* Added missing type constraints in FCS. ([PR #18241](https://github.com/dotnet/fsharp/pull/18241))
 
 ### Changed
 
diff --git a/src/Compiler/Symbols/Symbols.fs b/src/Compiler/Symbols/Symbols.fs
index 36823f65dc0..470327f59cd 100644
--- a/src/Compiler/Symbols/Symbols.fs
+++ b/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 _.IsAllowsRefStructConstraint = 
+        match cx with 
+        | TyparConstraint.AllowsRefStruct _ -> true 
+        | _ -> false
+
     override x.ToString() = "<type constraint>"
 
 type FSharpInlineAnnotation = 
diff --git a/src/Compiler/Symbols/Symbols.fsi b/src/Compiler/Symbols/Symbols.fsi
index 5c26d2d42ea..49742673d58 100644
--- a/src/Compiler/Symbols/Symbols.fsi
+++ b/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 IsAllowsRefStructConstraint: bool
+
 [<RequireQualifiedAccess>]
 type FSharpInlineAnnotation =
 
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
index 6004f3fb62d..13180c3b649 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl
@@ -5398,6 +5398,8 @@ FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsRequiresDefa
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsSimpleChoiceConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsSupportsNullConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsUnmanagedConstraint
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsNotSupportsNullConstraint
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsAllowsRefStructConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsCoercesToConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsComparisonConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsDefaultsToConstraint()
@@ -5411,6 +5413,8 @@ FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsRequires
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsSimpleChoiceConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsSupportsNullConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsUnmanagedConstraint()
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsNotSupportsNullConstraint()
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsAllowsRefStructConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDefaultsToConstraint DefaultsToConstraintData
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDefaultsToConstraint get_DefaultsToConstraintData()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDelegateConstraint DelegateConstraintData
diff --git a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
index 6004f3fb62d..13180c3b649 100644
--- a/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
+++ b/tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl
@@ -5398,6 +5398,8 @@ FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsRequiresDefa
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsSimpleChoiceConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsSupportsNullConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsUnmanagedConstraint
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsNotSupportsNullConstraint
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean IsAllowsRefStructConstraint
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsCoercesToConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsComparisonConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsDefaultsToConstraint()
@@ -5411,6 +5413,8 @@ FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsRequires
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsSimpleChoiceConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsSupportsNullConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsUnmanagedConstraint()
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsNotSupportsNullConstraint()
+FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: Boolean get_IsAllowsRefStructConstraint()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDefaultsToConstraint DefaultsToConstraintData
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDefaultsToConstraint get_DefaultsToConstraintData()
 FSharp.Compiler.Symbols.FSharpGenericParameterConstraint: FSharp.Compiler.Symbols.FSharpGenericParameterDelegateConstraint DelegateConstraintData
diff --git a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
index 1a5e3d85c4a..81cc143b139 100644
--- a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl
@@ -40,7 +40,7 @@
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-508::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000082][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-508::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000008B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-508::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000094][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Symbols+fullName@2490-1::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000015][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Symbols+fullName@2495-1::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000015][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CreateILModule+MainModuleBuilder::ConvertProductVersionToILVersionInfo(string)][offset 0x00000011][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.StaticLinking+TypeForwarding::followTypeForwardForILTypeRef([FSharp.Compiler.Service]FSharp.Compiler.AbstractIL.IL+ILTypeRef)][offset 0x00000010][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CompilerOptions::getCompilerOption([FSharp.Compiler.Service]FSharp.Compiler.CompilerOptions+CompilerOption, [FSharp.Core]Microsoft.FSharp.Core.FSharpOption`1<int32>)][offset 0x000000E6][found Char] Unexpected type on the stack.
diff --git a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_netstandard2.0.bsl b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_netstandard2.0.bsl
index 77ba0d7133e..588f29f5a96 100644
--- a/tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_netstandard2.0.bsl
+++ b/tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_netstandard2.0.bsl
@@ -39,7 +39,7 @@
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-529::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000064][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-529::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x0000006D][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$ServiceLexing+clo@921-529::Invoke([FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<System.Tuple`3<FSharp.Compiler.Parser+token,int32,int32>,Microsoft.FSharp.Core.Unit>)][offset 0x00000076][found Char] Unexpected type on the stack.
-[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Symbols+fullName@2490-3::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000030][found Char] Unexpected type on the stack.
+[IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Symbols+fullName@2495-3::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000030][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Driver+ProcessCommandLineFlags@301-1::Invoke(string)][offset 0x0000000B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.Driver+ProcessCommandLineFlags@301-1::Invoke(string)][offset 0x00000014][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CreateILModule+MainModuleBuilder::ConvertProductVersionToILVersionInfo(string)][offset 0x00000010][found Char] Unexpected type on the stack.