Filter "missing method body" error when emitting metadata-only (#18542)

src/Compilers/CSharp/Portable/Compilation/CSharpCompilation.cs

@@ -2311,7 +2311,14 @@ internal override StrongNameKeys StrongNameKeys
         {
             // The diagnostics should include syntax and declaration errors. We insert these before calling Emitter.Emit, so that the emitter
             // does not attempt to emit if there are declaration errors (but we do insert all errors from method body binding...)
-            bool hasDeclarationErrors = !FilterAndAppendDiagnostics(diagnostics, GetDiagnostics(CompilationStage.Declare, true, cancellationToken));
+            PooledHashSet<int> excludeDiagnostics = null;
+            if (emitMetadataOnly)
+            {
+                excludeDiagnostics = PooledHashSet<int>.GetInstance();
+                excludeDiagnostics.Add((int)ErrorCode.ERR_ConcreteMissingBody);
+            }
+            bool hasDeclarationErrors = !FilterAndAppendDiagnostics(diagnostics, GetDiagnostics(CompilationStage.Declare, true, cancellationToken), excludeDiagnostics);
+            excludeDiagnostics?.Free();
 
             // TODO (tomat): NoPIA:
             // EmbeddedSymbolManager.MarkAllDeferredSymbolsAsReferenced(this)

src/Compilers/CSharp/Test/Emit/Emit/CompilationEmitTests.cs

@@ -321,7 +321,6 @@ public void RefAssembly_ReferenceAssemblyAttributeAlsoInSource()
         [InlineData("public struct S { private int i; }", "public struct S { }", Match.Different)]
         [InlineData("private int i;", "", Match.RefOut)]
         [InlineData("public C() { }", "", Match.BothMetadataAndRefOut)]
-        //[InlineData("public int NoBody();", "public int NoBody() { }", Match.BothMetadataAndRefOut)] // PROTOTYPE(refout) Further refinement https://github.com/dotnet/roslyn/issues/17612
         public void RefAssembly_InvariantToSomeChanges(string left, string right, Match expectedMatch)
         {
             string sourceTemplate = @"
@@ -569,26 +568,40 @@ private static void VerifyRefAssemblyClient(string lib_cs, string source, Action
 
         [Theory]
         [InlineData("public int M() { error(); }", true)]
-        [InlineData("public int M() { error() }", false)] // Should be true. See follow-up issue https://github.com/dotnet/roslyn/issues/17612
+        [InlineData("public int M() { error() }", false)] // This may get relaxed. See follow-up issue https://github.com/dotnet/roslyn/issues/17612
+        [InlineData("public int M();", true)]
+        [InlineData("public int M() { int Local(); }", true)]
+        [InlineData("public C();", true)]
+        [InlineData("~ C();", true)]
         [InlineData("public Error M() { return null; }", false)] // This may get relaxed. See follow-up issue https://github.com/dotnet/roslyn/issues/17612
+        [InlineData("public static explicit operator C(int i);", true)]
+        [InlineData("public async Task M();", false)]
+        [InlineData("partial void M(); partial void M();", false)] // This may get relaxed. See follow-up issue https://github.com/dotnet/roslyn/issues/17612
         public void RefAssembly_IgnoresSomeDiagnostics(string change, bool expectSuccess)
         {
             string sourceTemplate = @"
-public class C
+using System.Threading.Tasks;
+public partial class C
 {
     CHANGE
 }
 ";
-            string source = sourceTemplate.Replace("CHANGE", change);
-            string name = GetUniqueName();
-            CSharpCompilation comp1 = CreateCompilationWithMscorlib(Parse(source),
-                options: TestOptions.DebugDll.WithDeterministic(true), assemblyName: name);
+            VerifyIgnoresDiagnostics(EmitOptions.Default.WithEmitMetadataOnly(false).WithTolerateErrors(false), success: false);
+            VerifyIgnoresDiagnostics(EmitOptions.Default.WithEmitMetadataOnly(true).WithTolerateErrors(false), success: expectSuccess);
 
-            using (var output = new MemoryStream())
+            void VerifyIgnoresDiagnostics(EmitOptions emitOptions, bool success)
             {
-                var emitResult = comp1.Emit(output, options: EmitOptions.Default.WithEmitMetadataOnly(true));
-                Assert.Equal(expectSuccess, emitResult.Success);
-                Assert.Equal(!expectSuccess, emitResult.Diagnostics.Any());
+                string source = sourceTemplate.Replace("CHANGE", change);
+                string name = GetUniqueName();
+                CSharpCompilation comp = CreateCompilationWithMscorlib(Parse(source),
+                    options: TestOptions.DebugDll.WithDeterministic(true), assemblyName: name);
+
+                using (var output = new MemoryStream())
+                {
+                    var emitResult = comp.Emit(output, options: emitOptions);
+                    Assert.Equal(!success, emitResult.Diagnostics.HasAnyErrors());
+                    Assert.Equal(success, emitResult.Success);
+                }
             }
         }
 

src/Compilers/Core/Portable/Compilation/Compilation.cs

@@ -1151,7 +1151,7 @@ internal void CompleteCompilationEventQueue_NoLock()
         /// <returns>True if there were no errors or warnings-as-errors.</returns>
         internal bool FilterAndAppendAndFreeDiagnostics(DiagnosticBag accumulator, ref DiagnosticBag incoming)
         {
-            bool result = FilterAndAppendDiagnostics(accumulator, incoming.AsEnumerableWithoutResolution());
+            bool result = FilterAndAppendDiagnostics(accumulator, incoming.AsEnumerableWithoutResolution(), exclude: null);
             incoming.Free();
             incoming = null;
             return result;
@@ -1161,13 +1161,18 @@ internal bool FilterAndAppendAndFreeDiagnostics(DiagnosticBag accumulator, ref D
         /// Filter out warnings based on the compiler options (/nowarn, /warn and /warnaserror) and the pragma warning directives.
         /// </summary>
         /// <returns>True when there is no error.</returns>
-        internal bool FilterAndAppendDiagnostics(DiagnosticBag accumulator, IEnumerable<Diagnostic> incoming)
+        internal bool FilterAndAppendDiagnostics(DiagnosticBag accumulator, IEnumerable<Diagnostic> incoming, HashSet<int> exclude)
         {
             bool hasError = false;
             bool reportSuppressedDiagnostics = Options.ReportSuppressedDiagnostics;
 
             foreach (Diagnostic d in incoming)
             {
+                if (exclude?.Contains(d.Code) == true)
+                {
+                    continue;
+                }
+
                 var filtered = Options.FilterDiagnostic(d);
                 if (filtered == null ||
                     (!reportSuppressedDiagnostics && filtered.IsSuppressed))

src/Compilers/VisualBasic/Portable/Compilation/VisualBasicCompilation.vb

@@ -2221,7 +2221,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
 
             ' The diagnostics should include syntax and declaration errors. We insert these before calling Emitter.Emit, so that we don't emit
             ' metadata if there are declaration errors or method body errors (but we do insert all errors from method body binding...)
-            Dim hasDeclarationErrors = Not FilterAndAppendDiagnostics(diagnostics, GetDiagnostics(CompilationStage.Declare, True, cancellationToken))
+            Dim hasDeclarationErrors = Not FilterAndAppendDiagnostics(diagnostics, GetDiagnostics(CompilationStage.Declare, True, cancellationToken), exclude:=Nothing)
 
             Dim moduleBeingBuilt = DirectCast(moduleBuilder, PEModuleBuilder)