Improve error reporting around lambdas and multiple overloads in VB

Fixes #2604.

src/Compilers/VisualBasic/Portable/Binding/Binder_Invocation.vb

@@ -1809,14 +1809,12 @@ ProduceBoundNode:
             queryMode As Boolean,
             callerInfoOpt As VisualBasicSyntaxNode
         )
-            Dim diagnosticInfos = ArrayBuilder(Of DiagnosticInfo).GetInstance(candidates.Count)
+            Dim diagnosticPerSymbol = ArrayBuilder(Of KeyValuePair(Of Symbol, ImmutableArray(Of Diagnostic))).GetInstance(candidates.Count)
 
             If arguments.IsDefault Then
                 arguments = ImmutableArray(Of BoundExpression).Empty
             End If
 
-            ' TODO: Collapse the same errors reported for all candidates (see Semantics::ReportOverloadResolutionFailure in Dev10).
-
             For i As Integer = 0 To candidates.Count - 1 Step 1
 
                 ' See if we need to consider both expanded and unexpanded version of the same method.
@@ -1846,56 +1844,106 @@ ProduceBoundNode:
                                                          callerInfoOpt:=callerInfoOpt,
                                                          representCandidateInDiagnosticsOpt:=Nothing)
 
-                Dim symbol = candidates(i).Candidate.UnderlyingSymbol
-                Dim isExtension As Boolean = symbol.IsReducedExtensionMethod()
+                diagnosticPerSymbol.Add(KeyValuePair.Create(candidates(i).Candidate.UnderlyingSymbol, candidateDiagnostics.ToReadOnlyAndFree()))
 
-                Dim sealedCandidateDiagnostics = candidateDiagnostics.ToReadOnlyAndFree()
+            Next
 
-                ' When reporting errors for an AddressOf, Dev 10 shows different error messages depending on how many
-                ' errors there are per candidate.
-                ' One narrowing error will be shown like:
-                '     'Public Sub foo6(p As Integer, p2 As Byte)': Option Strict On disallows implicit conversions from 'Integer' to 'Byte'.
-                ' More than one narrowing issues in the parameters are abbreviated with:
-                '     'Public Sub foo6(p As Byte, p2 As Byte)': Method does not have a signature compatible with the delegate.
+            ' See if there are errors that are reported for each candidate at the same location within a lambda argument.  
+            ' Report them and don't report remaining diagnostics for each symbol separately.
+            If Not ReportCommonErrorsFromLambdas(diagnosticPerSymbol, arguments, diagnostics) Then
+                Dim diagnosticInfos = ArrayBuilder(Of DiagnosticInfo).GetInstance(candidates.Count)
 
-                If delegateSymbol Is Nothing OrElse Not sealedCandidateDiagnostics.Skip(1).Any() Then
-                    If isExtension Then
-                        For Each iDiagnostic In sealedCandidateDiagnostics
-                            diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_ExtensionMethodOverloadCandidate3,
+                For i As Integer = 0 To diagnosticPerSymbol.Count - 1
+                    Dim symbol = diagnosticPerSymbol(i).Key
+                    Dim isExtension As Boolean = symbol.IsReducedExtensionMethod()
+
+                    Dim sealedCandidateDiagnostics = diagnosticPerSymbol(i).Value
+
+                    ' When reporting errors for an AddressOf, Dev 10 shows different error messages depending on how many
+                    ' errors there are per candidate.
+                    ' One narrowing error will be shown like:
+                    '     'Public Sub foo6(p As Integer, p2 As Byte)': Option Strict On disallows implicit conversions from 'Integer' to 'Byte'.
+                    ' More than one narrowing issues in the parameters are abbreviated with:
+                    '     'Public Sub foo6(p As Byte, p2 As Byte)': Method does not have a signature compatible with the delegate.
+
+                    If delegateSymbol Is Nothing OrElse Not sealedCandidateDiagnostics.Skip(1).Any() Then
+                        If isExtension Then
+                            For Each iDiagnostic In sealedCandidateDiagnostics
+                                diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_ExtensionMethodOverloadCandidate3,
                                                                        symbol, symbol.ContainingType, DirectCast(iDiagnostic, DiagnosticWithInfo).Info))
-                        Next
+                            Next
+                        Else
+                            For Each iDiagnostic In sealedCandidateDiagnostics
+                                Dim msg = VisualBasicDiagnosticFormatter.Instance.Format(iDiagnostic.WithLocation(Location.None))
+                                diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_OverloadCandidate2, symbol, DirectCast(iDiagnostic, DiagnosticWithInfo).Info))
+                            Next
+                        End If
                     Else
-                        For Each iDiagnostic In sealedCandidateDiagnostics
-                            Dim msg = VisualBasicDiagnosticFormatter.Instance.Format(iDiagnostic.WithLocation(Location.None))
-                            diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_OverloadCandidate2, symbol, DirectCast(iDiagnostic, DiagnosticWithInfo).Info))
-                        Next
-                    End If
-                Else
-                    If isExtension Then
-                        diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_ExtensionMethodOverloadCandidate3,
+                        If isExtension Then
+                            diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_ExtensionMethodOverloadCandidate3,
                                                                    symbol, symbol.ContainingType,
                                                                    ErrorFactory.ErrorInfo(ERRID.ERR_DelegateBindingMismatch, symbol)))
-                    Else
-                        diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_OverloadCandidate2,
+                        Else
+                            diagnosticInfos.Add(ErrorFactory.ErrorInfo(ERRID.ERR_OverloadCandidate2,
                                                                    symbol,
                                                                    ErrorFactory.ErrorInfo(ERRID.ERR_DelegateBindingMismatch, symbol)))
+                        End If
                     End If
-                End If
-            Next
+                Next
 
-            Dim diagnosticCoumpoundInfos() As DiagnosticInfo = diagnosticInfos.ToArrayAndFree()
-            If delegateSymbol Is Nothing Then
-                ReportDiagnostic(diagnostics, diagnosticLocation,
+                Dim diagnosticCoumpoundInfos() As DiagnosticInfo = diagnosticInfos.ToArrayAndFree()
+                If delegateSymbol Is Nothing Then
+                    ReportDiagnostic(diagnostics, diagnosticLocation,
                                  ErrorFactory.ErrorInfo(errorNo, CustomSymbolDisplayFormatter.ShortErrorName(candidates(0).Candidate.UnderlyingSymbol),
                                                         New CompoundDiagnosticInfo(diagnosticCoumpoundInfos)))
-            Else
-                ReportDiagnostic(diagnostics, diagnosticLocation,
+                Else
+                    ReportDiagnostic(diagnostics, diagnosticLocation,
                                  ErrorFactory.ErrorInfo(errorNo, CustomSymbolDisplayFormatter.ShortErrorName(candidates(0).Candidate.UnderlyingSymbol),
                                                         CustomSymbolDisplayFormatter.DelegateSignature(delegateSymbol),
                                                         New CompoundDiagnosticInfo(diagnosticCoumpoundInfos)))
+                End If
             End If
+
+            diagnosticPerSymbol.Free()
         End Sub
 
+        Private Shared Function ReportCommonErrorsFromLambdas(
+            diagnosticPerSymbol As ArrayBuilder(Of KeyValuePair(Of Symbol, ImmutableArray(Of Diagnostic))),
+            arguments As ImmutableArray(Of BoundExpression),
+            diagnostics As DiagnosticBag
+        ) As Boolean
+            Dim haveCommonErrors As Boolean = False
+
+            For Each diagnostic In diagnosticPerSymbol(0).Value
+                If diagnostic.Severity <> DiagnosticSeverity.Error Then
+                    Continue For
+                End If
+
+                For Each argument In arguments
+                    If argument.Syntax.SyntaxTree Is diagnostic.Location.SourceTree AndAlso
+                       argument.Kind = BoundKind.UnboundLambda Then
+                        If argument.Syntax.Span.Contains(diagnostic.Location.SourceSpan) Then
+                            Dim common As Boolean = True
+                            For i As Integer = 1 To diagnosticPerSymbol.Count - 1
+                                If Not diagnosticPerSymbol(i).Value.Contains(diagnostic) Then
+                                    common = False
+                                    Exit For
+                                End If
+                            Next
+
+                            If common Then
+                                haveCommonErrors = True
+                                diagnostics.Add(diagnostic)
+                            End If
+
+                            Exit For
+                        End If
+                    End If
+                Next
+            Next
+
+            Return haveCommonErrors
+        End Function
 
         ''' <summary>
         ''' Should be kept in sync with OverloadResolution.MatchArguments. Anything that 

src/Compilers/VisualBasic/Test/Semantic/Binding/BindingErrorTests.vb

@@ -5909,11 +5909,9 @@ End Class
 </compilation>, {SystemCoreRef})
             CompilationUtils.AssertTheseDiagnostics(compilation,
 <expected>
-BC30518: Overload resolution failed because no accessible 'Where' can be called with these arguments:
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': 'Exit Try' can only appear inside a 'Try' statement.
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': 'Exit Try' can only appear inside a 'Try' statement.
-        x.Where(Function(y)
-          ~~~~~
+BC30393: 'Exit Try' can only appear inside a 'Try' statement.
+                        Exit Try
+                        ~~~~~~~~
 </expected>)
         End Sub
 
@@ -8178,11 +8176,9 @@ End Class
 </compilation>, {SystemCoreRef})
             CompilationUtils.AssertTheseDiagnostics(compilation,
 <expected>
-BC30518: Overload resolution failed because no accessible 'Where' can be called with these arguments:
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': Branching out of a 'Finally' is not valid.
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': Branching out of a 'Finally' is not valid.
-        x.Where(Function(y)
-          ~~~~~
+BC30101: Branching out of a 'Finally' is not valid.
+                        Exit Function
+                        ~~~~~~~~~~~~~
 BC42353: Function '&lt;anonymous method>' doesn't return a value on all code paths. Are you missing a 'Return' statement?
                 End Function)
                 ~~~~~~~~~~~~

src/Compilers/VisualBasic/Test/Semantic/Binding/GotoTests.vb

@@ -44,11 +44,9 @@ End Class
 
             AssertTheseDiagnostics(compilation,
 <expected>
-BC30518: Overload resolution failed because no accessible 'Where' can be called with these arguments:
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': Branching out of a 'Finally' is not valid.
-    Extension method 'Public Function Where(predicate As Func(Of Integer, Integer, Boolean)) As IEnumerable(Of Integer)' defined in 'Enumerable': Branching out of a 'Finally' is not valid.
-        lists.Where(Function(ByVal item)
-              ~~~~~
+BC30101: Branching out of a 'Finally' is not valid.
+                            GoTo lab1
+                                 ~~~~
             </expected>)
         End Sub
 

src/Compilers/VisualBasic/Test/Semantic/Semantics/OverloadResolution.vb

@@ -5475,5 +5475,58 @@ BC30661: Field or property 'p1' is not found.
 ]]></expected>)
         End Sub
 
+        <Fact, WorkItem(2604, "https://github.com/dotnet/roslyn/issues/2604")>
+        Public Sub FailureDueToAnErrorInALambda()
+
+            Dim compilationDef =
+<compilation>
+    <file name="a.vb"><![CDATA[
+Module Module1
+
+    Sub Main()
+        M0(0, Function() doesntexist)
+        M1(0, Function() doesntexist)
+        M2(0, Function() doesntexist)
+    End Sub
+
+    Sub M0(x As Integer, y As System.Func(Of Integer))
+    End Sub
+
+    Sub M1(x As Integer, y As System.Func(Of Integer))
+    End Sub
+
+    Sub M1(x As Long, y As System.Func(Of Long))
+    End Sub
+
+    Sub M2(x As Integer, y As System.Func(Of Integer))
+    End Sub
+
+    Sub M2(x As c1, y As System.Func(Of Long))
+    End Sub
+End Module
+
+Class c1
+End Class
+]]>
+
+    </file>
+</compilation>
+
+            Dim compilation = CompilationUtils.CreateCompilationWithMscorlibAndVBRuntime(compilationDef, TestOptions.ReleaseExe)
+
+            CompilationUtils.AssertTheseDiagnostics(compilation,
+<expected><![CDATA[
+BC30451: 'doesntexist' is not declared. It may be inaccessible due to its protection level.
+        M0(0, Function() doesntexist)
+                         ~~~~~~~~~~~
+BC30451: 'doesntexist' is not declared. It may be inaccessible due to its protection level.
+        M1(0, Function() doesntexist)
+                         ~~~~~~~~~~~
+BC30451: 'doesntexist' is not declared. It may be inaccessible due to its protection level.
+        M2(0, Function() doesntexist)
+                         ~~~~~~~~~~~
+]]></expected>)
+        End Sub
+
     End Class
 End Namespace

src/Compilers/VisualBasic/Test/Semantic/Semantics/TypeArgumentInference.vb

@@ -1826,13 +1826,9 @@ BC42021: Cannot infer a return type because more than one type is possible; 'Obj
 
             AssertTheseDiagnostics(compilation,
 <expected>
-BC30518: Overload resolution failed because no accessible '[Select]' can be called with these arguments:
-    Extension method 'Public Function [Select](Of TResult)(selector As Func(Of SnapshotSpan, TResult)) As IEnumerable(Of TResult)' defined in 'Enumerable': Cannot infer a return type because more than one type is possible. Consider adding an 'As' clause to specify the return type.
-    Extension method 'Public Function [Select](Of TResult)(selector As Func(Of SnapshotSpan, TResult)) As IEnumerable(Of TResult)' defined in 'Enumerable': Data type(s) of the type parameter(s) cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error.
-    Extension method 'Public Function [Select](Of TResult)(selector As Func(Of SnapshotSpan, Integer, TResult)) As IEnumerable(Of TResult)' defined in 'Enumerable': Cannot infer a return type because more than one type is possible. Consider adding an 'As' clause to specify the return type.
-    Extension method 'Public Function [Select](Of TResult)(selector As Func(Of SnapshotSpan, Integer, TResult)) As IEnumerable(Of TResult)' defined in 'Enumerable': Data type(s) of the type parameter(s) cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error.
+BC36734: Cannot infer a return type because more than one type is possible. Consider adding an 'As' clause to specify the return type.
         Dim replacementSpans = sourceSpans.Select(Function(ss)
-                                           ~~~~~~
+                                                  ~~~~~~~~~~~~
 </expected>)
         End Sub