Merge pull request #30721 from 333fred/incremental-bind-embbeded

Correctly return cached blocks in the IncrementalBinder for things th…

src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs

@@ -1599,7 +1599,7 @@ protected virtual LocalFunctionSymbol LookupLocalFunction(SyntaxToken nameToken)
         /// </summary>
         internal virtual uint LocalScopeDepth => Next.LocalScopeDepth;
 
-        internal BoundBlock BindEmbeddedBlock(BlockSyntax node, DiagnosticBag diagnostics)
+        internal virtual BoundBlock BindEmbeddedBlock(BlockSyntax node, DiagnosticBag diagnostics)
         {
             return BindBlock(node, diagnostics);
         }

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

@@ -2091,6 +2091,13 @@ public override BoundStatement BindStatement(StatementSyntax node, DiagnosticBag
                 return (BoundStatement)boundNode;
             }
 
+            internal override BoundBlock BindEmbeddedBlock(BlockSyntax node, DiagnosticBag diagnostics)
+            {
+                BoundBlock block = (BoundBlock)TryGetBoundNodeFromMap(node) ?? base.BindEmbeddedBlock(node, diagnostics);
+                Debug.Assert(!block.WasCompilerGenerated);
+                return block;
+            }
+
             private BoundNode TryGetBoundNodeFromMap(CSharpSyntaxNode node)
             {
                 ImmutableArray<BoundNode> boundNodes = _semanticModel.GuardedGetBoundNodesFromMap(node);

src/Compilers/CSharp/Test/IOperation/IOperation/IOperationTests.cs

@@ -493,6 +493,39 @@ void M(int x)
 ");
         }
 
+        [Fact, WorkItem(26649, "https://github.com/dotnet/roslyn/issues/26649")]
+        public void IncrementalBindingReusesBlock()
+        {
+            var source = @"
+class C
+{
+    void M()
+    {
+        try
+        {
+        }
+        catch (Exception e)
+        {
+            throw new Exception();
+        }
+    }
+}";
+
+            var compilation = CreateCompilation(source);
+            var syntaxTree = compilation.SyntaxTrees[0];
+            var semanticModel = compilation.GetSemanticModel(syntaxTree);
+
+            // We want to get the IOperation for the { throw new Exception(); } first, and then for the containing catch block, to
+            // force the semantic model to bind the inner first. It should reuse that inner block when binding the outer catch.
+
+            var catchBlock = syntaxTree.GetRoot().DescendantNodes().OfType<CatchClauseSyntax>().Single();
+            var exceptionBlock = catchBlock.Block;
+
+            var blockOperation = semanticModel.GetOperation(exceptionBlock);
+            var catchOperation = (ICatchClauseOperation)semanticModel.GetOperation(catchBlock);
+            Assert.Same(blockOperation, catchOperation.Handler);
+        }
+
         private static void VerifyRootAndModelForOperationAncestors(
             IOperation operation,
             SemanticModel model,