static IEnumerable <TypeDefinition> GetCompilerGeneratedNestedTypes(TypeDefinition type)
{
foreach (var nestedType in type.NestedTypes)
{
if (!CompilerGeneratedNames.IsGeneratedMemberName(nestedType.Name))
{
continue;
}
yield return(nestedType);
foreach (var recursiveNestedType in GetCompilerGeneratedNestedTypes(nestedType))
{
yield return(recursiveNestedType);
}
}
}
void PopulateCacheForType(TypeDefinition type)
{
// Avoid repeat scans of the same type
if (!_typesWithPopulatedCache.Add(type))
{
return;
}
var callGraph = new CompilerGeneratedCallGraph();
var callingMethods = new HashSet <MethodDefinition> ();
void ProcessMethod(MethodDefinition method)
{
bool isStateMachineMember = CompilerGeneratedNames.IsStateMachineType(method.DeclaringType.Name);
if (!CompilerGeneratedNames.IsLambdaOrLocalFunction(method.Name))
{
if (!isStateMachineMember)
{
// If it's not a nested function, track as an entry point to the call graph.
var added = callingMethods.Add(method);
Debug.Assert(added);
}
}
else
{
// We don't expect lambdas or local functions to be emitted directly into
// state machine types.
Debug.Assert(!isStateMachineMember);
}
// Discover calls or references to lambdas or local functions. This includes
// calls to local functions, and lambda assignments (which use ldftn).
if (method.Body != null)
{
foreach (var instruction in method.Body.Instructions)
{
if (instruction.OpCode.OperandType != OperandType.InlineMethod)
{
continue;
}
MethodDefinition?lambdaOrLocalFunction = _context.TryResolve((MethodReference)instruction.Operand);
if (lambdaOrLocalFunction == null)
{
continue;
}
if (!CompilerGeneratedNames.IsLambdaOrLocalFunction(lambdaOrLocalFunction.Name))
{
continue;
}
if (isStateMachineMember)
{
callGraph.TrackCall(method.DeclaringType, lambdaOrLocalFunction);
}
else
{
callGraph.TrackCall(method, lambdaOrLocalFunction);
}
}
}
// Discover state machine methods.
if (!method.HasCustomAttributes)
{
return;
}
foreach (var attribute in method.CustomAttributes)
{
if (attribute.AttributeType.Namespace != "System.Runtime.CompilerServices")
{
continue;
}
switch (attribute.AttributeType.Name)
{
case "AsyncIteratorStateMachineAttribute":
case "AsyncStateMachineAttribute":
case "IteratorStateMachineAttribute":
TypeDefinition?stateMachineType = GetFirstConstructorArgumentAsType(attribute);
if (stateMachineType == null)
{
break;
}
Debug.Assert(stateMachineType.DeclaringType == type ||
(CompilerGeneratedNames.IsGeneratedMemberName(stateMachineType.DeclaringType.Name) &&
stateMachineType.DeclaringType.DeclaringType == type));
callGraph.TrackCall(method, stateMachineType);
if (!_compilerGeneratedTypeToUserCodeMethod.TryAdd(stateMachineType, method))
{
var alreadyAssociatedMethod = _compilerGeneratedTypeToUserCodeMethod[stateMachineType];
_context.LogWarning(new MessageOrigin(method), DiagnosticId.MethodsAreAssociatedWithStateMachine, method.GetDisplayName(), alreadyAssociatedMethod.GetDisplayName(), stateMachineType.GetDisplayName());
}
break;
}
}
}
// Look for state machine methods, and methods which call local functions.
foreach (MethodDefinition method in type.Methods)
{
ProcessMethod(method);
}
// Also scan compiler-generated state machine methods (in case they have calls to nested functions),
// and nested functions inside compiler-generated closures (in case they call other nested functions).
// State machines can be emitted into lambda display classes, so we need to go down at least two
// levels to find calls from iterator nested functions to other nested functions. We just recurse into
// all compiler-generated nested types to avoid depending on implementation details.
foreach (var nestedType in GetCompilerGeneratedNestedTypes(type))
{
foreach (var method in nestedType.Methods)
{
ProcessMethod(method);
}
}
// Now we've discovered the call graphs for calls to nested functions.
// Use this to map back from nested functions to the declaring user methods.
// Note: This maps all nested functions back to the user code, not to the immediately
// declaring local function. The IL doesn't contain enough information in general for
// us to determine the nesting of local functions and lambdas.
// Note: this only discovers nested functions which are referenced from the user
// code or its referenced nested functions. There is no reliable way to determine from
// IL which user code an unused nested function belongs to.
foreach (var userDefinedMethod in callingMethods)
{
foreach (var compilerGeneratedMember in callGraph.GetReachableMembers(userDefinedMethod))
{
switch (compilerGeneratedMember)
{
case MethodDefinition nestedFunction:
Debug.Assert(CompilerGeneratedNames.IsLambdaOrLocalFunction(nestedFunction.Name));
// Nested functions get suppressions from the user method only.
if (!_compilerGeneratedMethodToUserCodeMethod.TryAdd(nestedFunction, userDefinedMethod))
{
var alreadyAssociatedMethod = _compilerGeneratedMethodToUserCodeMethod[nestedFunction];
_context.LogWarning(new MessageOrigin(userDefinedMethod), DiagnosticId.MethodsAreAssociatedWithUserMethod, userDefinedMethod.GetDisplayName(), alreadyAssociatedMethod.GetDisplayName(), nestedFunction.GetDisplayName());
}
break;
case TypeDefinition stateMachineType:
// Types in the call graph are always state machine types
// For those all their methods are not tracked explicitly in the call graph; instead, they
// are represented by the state machine type itself.
// We are already tracking the association of the state machine type to the user code method
// above, so no need to track it here.
Debug.Assert(CompilerGeneratedNames.IsStateMachineType(stateMachineType.Name));
break;
default:
throw new InvalidOperationException();
}
}
}
}
// For state machine types/members, maps back to the state machine method.
// For local functions and lambdas, maps back to the owning method in user code (not the declaring
// lambda or local function, because the IL doesn't contain enough information to figure this out).
public bool TryGetOwningMethodForCompilerGeneratedMember(IMemberDefinition sourceMember, [NotNullWhen(true)] out MethodDefinition?owningMethod)
{
owningMethod = null;
if (sourceMember == null)
{
return(false);
}
MethodDefinition?compilerGeneratedMethod = sourceMember as MethodDefinition;
if (compilerGeneratedMethod != null)
{
if (_compilerGeneratedMethodToUserCodeMethod.TryGetValue(compilerGeneratedMethod, out owningMethod))
{
return(true);
}
}
TypeDefinition sourceType = (sourceMember as TypeDefinition) ?? sourceMember.DeclaringType;
if (_compilerGeneratedTypeToUserCodeMethod.TryGetValue(sourceType, out owningMethod))
{
return(true);
}
if (!CompilerGeneratedNames.IsGeneratedMemberName(sourceMember.Name) && !CompilerGeneratedNames.IsGeneratedMemberName(sourceType.Name))
{
return(false);
}
// sourceType is a state machine type, or the type containing a lambda or local function.
var typeToCache = sourceType;
// Look in the declaring type if this is a compiler-generated type (state machine or display class).
// State machines can be emitted into display classes, so we may also need to go one more level up.
// To avoid depending on implementation details, we go up until we see a non-compiler-generated type.
// This is the counterpart to GetCompilerGeneratedNestedTypes.
while (typeToCache != null && CompilerGeneratedNames.IsGeneratedMemberName(typeToCache.Name))
{
typeToCache = typeToCache.DeclaringType;
}
if (typeToCache == null)
{
return(false);
}
// Search all methods to find the one which points to the type as its
// state machine implementation.
PopulateCacheForType(typeToCache);
if (compilerGeneratedMethod != null)
{
if (_compilerGeneratedMethodToUserCodeMethod.TryGetValue(compilerGeneratedMethod, out owningMethod))
{
return(true);
}
}
if (_compilerGeneratedTypeToUserCodeMethod.TryGetValue(sourceType, out owningMethod))
{
return(true);
}
return(false);
}
