Enforce compiler-semantic attributes in signature conformance (issue #19560)

docs/release-notes/.FSharp.Compiler.Service/11.0.100.md

@@ -68,6 +68,7 @@
 * Reference assembly MVIDs are now deterministic across compiler invocations. Previously, `--refout` / `<ProduceReferenceAssembly>true</ProduceReferenceAssembly>` produced a different MVID every build because the implied signature hash used .NET's randomized `String.GetHashCode()`. ([Issue #19751](https://github.com/dotnet/fsharp/issues/19751), [PR #19801](https://github.com/dotnet/fsharp/pull/19801))
 * Parser: recover on unfinished if and binary expressions
 ([PR #19724](https://github.com/dotnet/fsharp/pull/19724))
+* Enforce that compiler-semantic attributes (`NoDynamicInvocation`) present on a value in a `.fs` implementation file are also declared in the corresponding `.fsi` signature file. Previously such attributes were silently dropped because tooling skips implementations when a signature is present. ([Issue #19560](https://github.com/dotnet/fsharp/issues/19560), [PR #19880](https://github.com/dotnet/fsharp/pull/19880))
 
 ### Added
 

docs/release-notes/.FSharp.Core/11.0.100.md

@@ -3,3 +3,4 @@
 * Fix `Array.exists2` documentation examples to use equal-length arrays; the previous examples would throw `ArgumentException` at runtime instead of returning the documented `false`/`true` values. ([PR #19672](https://github.com/dotnet/fsharp/pull/19672))
 * Move `Async.StartChild` to the "Starting Async Computations" docs category alongside `Async.StartChildAsTask`. ([Issue #19667](https://github.com/dotnet/fsharp/issues/19667))
 * Add `InlineIfLambda` to `Array.init` ([PR #19869](https://github.com/dotnet/fsharp/pull/19869))
+* Mirror `[<NoDynamicInvocation>]` from FSharp.Core implementation files into the matching `.fsi` signature files (in `nativeptr.fsi` and `prim-types.fsi`) so the attribute reaches consumers and tooling. Required by the new signature-enforced-attributes check. ([Issue #19560](https://github.com/dotnet/fsharp/issues/19560), [PR #19880](https://github.com/dotnet/fsharp/pull/19880))

src/Compiler/Checking/SignatureConformance.fs

@@ -16,6 +16,7 @@ open FSharp.Compiler.InfoReader
 open FSharp.Compiler.Syntax
 open FSharp.Compiler.SyntaxTreeOps
 open FSharp.Compiler.Text
+open FSharp.Compiler.TcGlobals
 open FSharp.Compiler.TypedTree
 open FSharp.Compiler.TypedTreeBasics
 open FSharp.Compiler.TypedTreeOps
@@ -41,6 +42,20 @@ exception InterfaceNotRevealed of DisplayEnv * TType * range
 
 exception ArgumentsInSigAndImplMismatch of sigArg: Ident * implArg: Ident
 
+/// The set of well-known Val-level attributes whose presence on an implementation
+/// must be matched in the signature. These attributes change the contract observed
+/// by consumers of a value/member (inlining behaviour, dynamic dispatch, codegen),
+/// and tooling does not consult the implementation when a signature file is present
+/// (so attributes only on the impl are silently lost). Adding a new attribute here
+/// is the ONE PLACE required to enforce its presence in the signature.
+let private signatureEnforcedAttributes (g: TcGlobals) : (string * (Val -> bool)) list =
+    [
+      "NoDynamicInvocation",
+        (fun (v: Val) ->
+            ValHasWellKnownAttribute g WellKnownValAttributes.NoDynamicInvocationAttribute_True v
+            || ValHasWellKnownAttribute g WellKnownValAttributes.NoDynamicInvocationAttribute_False v)
+    ]
+
 exception DefinitionsInSigAndImplNotCompatibleAbbreviationsDiffer of
     denv: DisplayEnv *
     implTycon:Tycon *
@@ -368,6 +383,13 @@ type Checker(g, amap, denv, remapInfo: SignatureRepackageInfo, checkingSig) =
             let mk_err kind denv f = ValueNotContained(kind,denv, infoReader, implModRef, implVal, sigVal, f)
             let err denv f = errorR(mk_err RegularMismatch denv f); false
             let m = implVal.Range
+
+            // Enforce that compiler-semantic attributes present on the implementation
+            // are also present on the signature. See `signatureEnforcedAttributes` for
+            // the list and rationale.
+            for (attrName, hasAttr) in signatureEnforcedAttributes g do
+                if hasAttr implVal && not (hasAttr sigVal) then
+                    errorR(Error (FSComp.SR.implAttributeMissingFromSignature(attrName, implVal.DisplayName), m))
             if implVal.IsMutable <> sigVal.IsMutable then (err denv FSComp.SR.ValueNotContainedMutabilityAttributesDiffer)
             elif implVal.LogicalName <> sigVal.LogicalName then (err denv FSComp.SR.ValueNotContainedMutabilityNamesDiffer)
             elif (implVal.CompiledName g.CompilerGlobalState) <> (sigVal.CompiledName g.CompilerGlobalState) then (err denv FSComp.SR.ValueNotContainedMutabilityCompiledNamesDiffer)

src/Compiler/FSComp.txt

@@ -1818,4 +1818,5 @@ featurePreprocessorElif,"#elif preprocessor directive"
 3885,parsLetBangCannotBeLastInCE,"'%s' cannot be the final expression in a computation expression. Finish with 'return', 'return!', or a simple expression."
 3886,tcListLiteralWithSingleTupleElement,"This list expression contains a single tuple element. Did you mean to use ';' instead of ',' to separate list elements?"
 3887,ilCustomAttrInvalidArrayElemType,"The type '%s' is not a valid custom attribute argument type. Custom attribute arrays must have elements of primitive types, enums, string, System.Type, or System.Object."
+3888,implAttributeMissingFromSignature,"The attribute '%s' is present on '%s' in the implementation but not in the signature. Add the attribute to the signature, because tooling skips the implementation when a signature file is present."
 featureExceptionFieldSerializationSupport,"emit GetObjectData and field-restoring deserialization constructor for exception types"