Add further tests for pattern-matching in global code (#17092)

Fixes #14146

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTestBase.cs

@@ -121,6 +121,16 @@ protected static void VerifyModelForDeclarationPatternDuplicateInSameScope(Seman
             }
         }
 
+        protected static void VerifyNotAPatternField(SemanticModel model, IdentifierNameSyntax reference)
+        {
+            var symbol = model.GetSymbolInfo(reference).Symbol;
+
+            Assert.NotEqual(SymbolKind.Field, symbol.Kind);
+
+            Assert.Same(symbol, model.LookupSymbols(reference.SpanStart, name: reference.Identifier.ValueText).Single());
+            Assert.True(model.LookupNames(reference.SpanStart).Contains(reference.Identifier.ValueText));
+        }
+
         protected static void VerifyNotAPatternLocal(SemanticModel model, IdentifierNameSyntax reference)
         {
             var symbol = model.GetSymbolInfo(reference).Symbol;
@@ -301,6 +311,11 @@ protected static void VerifyModelNotSupported(SemanticModel model, params Identi
             }
         }
 
+        protected static void AssertNoGlobalStatements(SyntaxTree tree)
+        {
+            Assert.Empty(tree.GetRoot().DescendantNodes().OfType<GlobalStatementSyntax>());
+        }
+
         #endregion helpers
     }
 }

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests.cs

@@ -795,6 +795,13 @@ static bool Dummy(int x)
             var compilation = CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe);
             CompileAndVerify(compilation, expectedOutput: @"1
 True");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var x1Decl = GetPatternDeclaration(tree, "x1");
+            var x1Ref = GetReferences(tree, "x1").Single();
+            VerifyModelForDeclarationPattern(model, x1Decl, x1Ref);
         }
 
         [Fact]
@@ -902,6 +909,49 @@ static bool Print(object x)
             }
         }
 
+        [Fact]
+        public void Query_02()
+        {
+            var source =
+@"
+using System.Linq;
+
+public class X
+{
+    public static void Main()
+    {
+        Test1();
+    }
+
+    static void Test1()
+    {
+        var res = from x1 in new[] { 1 is var y1 && Print(y1) ? 2 : 0}
+                  select Print(x1);
+
+        res.ToArray(); 
+    }
+
+    static bool Print(object x) 
+    {
+        System.Console.WriteLine(x);
+        return true;
+    }
+}
+";
+            var compilation = CreateCompilationWithMscorlib45(source, new[] { SystemCoreRef }, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular);
+
+            CompileAndVerify(compilation, expectedOutput:
+@"1
+2");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var yDecl = GetPatternDeclaration(tree, "y1");
+            var yRef = GetReferences(tree, "y1").Single();
+            VerifyModelForDeclarationPattern(model, yDecl, yRef);
+        }
+
         [Fact]
         public void ExpressionBodiedFunctions_01()
         {
@@ -2359,6 +2409,14 @@ static System.Collections.IEnumerable Dummy(object y, object z)
             CompileAndVerify(compilation, expectedOutput:
 @"3
 3");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var x1Decl = GetPatternDeclaration(tree, "x1");
+            var x1Ref = GetReferences(tree, "x1").ToArray();
+            Assert.Equal(2, x1Ref.Length);
+            VerifyModelForDeclarationPattern(model, x1Decl, x1Ref);
         }
 
         [Fact]
@@ -2775,6 +2833,14 @@ static bool Dummy(object y, object z)
             CompileAndVerify(compilation, expectedOutput:
 @"System.InvalidOperationException
 System.InvalidOperationException");
+
+            var tree = compilation.SyntaxTrees.Single();
+            var model = compilation.GetSemanticModel(tree);
+
+            var x1Decl = GetPatternDeclaration(tree, "x1");
+            var x1Ref = GetReferences(tree, "x1").ToArray();
+            Assert.Equal(2, x1Ref.Length);
+            VerifyModelForDeclarationPattern(model, x1Decl, x1Ref);
         }
 
         [Fact]