ASTPrinter: fix nested signatures with inverses

A generic signature's `getInnermostGenericParams` will find the generic
parameters in the innermost scope. That's not quite right for printing
inverses, since we don't want to print an inverse for `T` when emitting
the generic signature of `f` below:

```swift
    struct S<T: ~Copyable, E> {
        func f() where E == Never {}
    }
```

Since `f` has its own generic signature, but doesn't define any generic
parameters, it shouldn't have an inverse emitted. The solution here is
to filter inverses by depth of the generic parameter.

We also want to print _all_ of the inverses in other situations, rather
than just the innermost ones. This aids in debugging and other
tools like the API digester.

resolves rdar://130179698

Author: kavon

include/swift/AST/ASTPrinter.h

@@ -107,6 +107,29 @@ enum class PrintStructureKind {
   FunctionParameterType,
 };
 
+/// ---------------------------------
+/// MARK: inverse filtering functors
+
+/// An inverse filter is just a function-object. Use one of the functors below
+/// to create such a filter.
+using InverseFilter = std::function<bool(const InverseRequirement &)>;
+
+/// Include all of them!
+class AllInverses {
+public:
+  bool operator()(const InverseRequirement &) const { return true; }
+};
+
+/// Only prints inverses on generic parameters defined in the specified
+/// generic context.
+class InversesAtDepth {
+  std::optional<unsigned> includedDepth;
+public:
+  InversesAtDepth(GenericContext *level);
+  bool operator()(const InverseRequirement &) const;
+};
+/// ---------------------------------
+
 /// An abstract class used to print an AST.
 class ASTPrinter {
   unsigned CurrentIndentation = 0;

lib/AST/ASTPrinter.cpp

@@ -974,7 +974,6 @@ class PrintAST : public ASTVisitor<PrintAST> {
     SwapSelfAndDependentMemberType = 8,
     PrintInherited = 16,
     PrintInverseRequirements = 32,
-    IncludeOuterInverses = 64,
   };
 
   /// The default generic signature flags for printing requirements.
@@ -1004,7 +1003,8 @@ class PrintAST : public ASTVisitor<PrintAST> {
   void
   printGenericSignature(GenericSignature genericSig,
                         unsigned flags,
-                        llvm::function_ref<bool(const Requirement &)> filter);
+                        llvm::function_ref<bool(const Requirement &)> filter,
+                        InverseFilter inverseFilter);
   void printSingleDepthOfGenericSignature(
       ArrayRef<GenericTypeParamType *> genericParams,
       ArrayRef<Requirement> requirements,
@@ -1693,9 +1693,13 @@ static unsigned getDepthOfRequirement(const Requirement &req) {
 
 void PrintAST::printGenericSignature(GenericSignature genericSig,
                                      unsigned flags) {
+  ASSERT(!((flags & InnermostOnly) && (flags & PrintInverseRequirements))
+         && "InnermostOnly + PrintInverseRequirements is not handled");
+
   printGenericSignature(genericSig, flags,
                         // print everything
-                        [&](const Requirement &) { return true; });
+                        [&](const Requirement &) { return true; },
+                        AllInverses());
 }
 
 // Erase any requirements involving invertible protocols.
@@ -1710,16 +1714,35 @@ static void eraseInvertibleProtocolConformances(
     });
 }
 
+InversesAtDepth::InversesAtDepth(GenericContext *level) {
+  includedDepth = std::nullopt;
+  // Does this generic context have its own generic parameters?
+  if (auto *list = level->getGenericParams()) {
+    includedDepth = list->getParams().back()->getDepth(); // use this depth.
+  }
+}
+bool InversesAtDepth::operator()(const InverseRequirement &inverse) const {
+  if (includedDepth) {
+    auto d = inverse.subject->castTo<GenericTypeParamType>()->getDepth();
+    return d == includedDepth.value();
+  }
+  return false;
+}
+
 void PrintAST::printGenericSignature(
     GenericSignature genericSig,
     unsigned flags,
-    llvm::function_ref<bool(const Requirement &)> filter) {
+    llvm::function_ref<bool(const Requirement &)> filter,
+    InverseFilter inverseFilter) {
 
   SmallVector<Requirement, 2> requirements;
   SmallVector<InverseRequirement, 2> inverses;
 
   if (flags & PrintInverseRequirements) {
     genericSig->getRequirementsWithInverses(requirements, inverses);
+    llvm::erase_if(inverses, [&](InverseRequirement inverse) -> bool {
+      return !inverseFilter(inverse);
+    });
   } else {
     requirements.append(genericSig.getRequirements().begin(),
                         genericSig.getRequirements().end());
@@ -1728,17 +1751,6 @@ void PrintAST::printGenericSignature(
       eraseInvertibleProtocolConformances(requirements);
   }
 
-  // Unless `IncludeOuterInverses` is enabled, limit inverses to the
-  // innermost generic parameters.
-  if (!(flags & IncludeOuterInverses) && !inverses.empty()) {
-    auto innerParams = genericSig.getInnermostGenericParams();
-    SmallPtrSet<TypeBase *, 4> innerParamSet(innerParams.begin(),
-                                             innerParams.end());
-    llvm::erase_if(inverses, [&](InverseRequirement inverse) -> bool {
-      return !innerParamSet.contains(inverse.subject.getPointer());
-    });
-  }
-
   if (flags & InnermostOnly) {
     auto genericParams = genericSig.getInnermostGenericParams();
 
@@ -2772,8 +2784,9 @@ void PrintAST::printDeclGenericRequirements(GenericContext *decl) {
   // In many cases, inverses should not be printed for outer generic parameters.
   // Exceptions to that include extensions, as it's valid to write an inverse
   // on the generic parameters they get from the extended nominal.
-  if (isa<ExtensionDecl>(decl))
-    flags |= IncludeOuterInverses;
+  InverseFilter inverseFilter = AllInverses();
+  if (!isa<ExtensionDecl>(decl))
+    inverseFilter = InversesAtDepth(decl);
 
   Printer.printStructurePre(PrintStructureKind::DeclGenericParameterClause);
   printGenericSignature(genericSig,
@@ -2782,7 +2795,8 @@ void PrintAST::printDeclGenericRequirements(GenericContext *decl) {
                           if (parentSig)
                             return !parentSig->isRequirementSatisfied(req);
                           return true;
-                        });
+                        },
+                        inverseFilter);
   Printer.printStructurePost(PrintStructureKind::DeclGenericParameterClause);
 }
 
@@ -3040,24 +3054,22 @@ void PrintAST::printExtension(ExtensionDecl *decl) {
       assert(baseGenericSig &&
              "an extension can't be generic if the base type isn't");
 
-      auto genSigFlags = defaultGenericRequirementFlags()
-                       | IncludeOuterInverses;
+      auto genSigFlags = defaultGenericRequirementFlags();
 
       // Disable printing inverses if the extension is adding a conformance
       // for an invertible protocol itself, as we do not infer any requirements
       // in such an extension. We need to print the whole signature:
       //     extension S: Copyable where T: Copyable
-      if (decl->isAddingConformanceToInvertible()) {
+      if (decl->isAddingConformanceToInvertible())
         genSigFlags &= ~PrintInverseRequirements;
-        genSigFlags &= ~IncludeOuterInverses;
-      }
 
       printGenericSignature(genericSig,
                             genSigFlags,
                             [baseGenericSig](const Requirement &req) -> bool {
         // Only include constraints that are not satisfied by the base type.
         return !baseGenericSig->isRequirementSatisfied(req);
-      });
+      },
+      AllInverses());
     }
   }
   if (Options.TypeDefinitions) {

test/ModuleInterface/Inputs/NoncopyableGenerics_Misc.swift

@@ -137,3 +137,8 @@ public struct Generic<T: Publik & ~Copyable> : (P & ~Copyable) {}
 public struct VeryNested: (P & (Q & ~Copyable & Publik) & (P & ~Copyable)) {}
 public struct Twice: P & ~Copyable, Q & ~Copyable {}
 public struct RegularTwice: ~Copyable, ~Copyable {}
+
+// coverage for rdar://130179698
+public struct Continuation<T: ~Copyable, E: Error> {
+  public func resume(returning value: consuming T) where E == Never {}
+}

test/ModuleInterface/noncopyable_generics.swift

@@ -215,6 +215,11 @@ import NoncopyableGenerics_Misc
 // CHECK-MISC-NEXT: public struct RegularTwice : ~Swift.Copyable, ~Swift.Copyable {
 // CHECK-MISC-NEXT: }
 
+// CHECK-MISC-NEXT: #if compiler(>=5.3) && $NoncopyableGenerics
+// CHECK-MISC-NEXT: public struct Continuation<T, E> where E : Swift.Error, T : ~Copyable {
+// CHECK-MISC-NOT:  ~
+// CHECK-MISC:      #endif
+
 // NOTE: below are extensions emitted at the end of NoncopyableGenerics_Misc.swift
 // CHECK-MISC: extension {{.*}}.VeryNested : {{.*}}.Publik {}
 

test/SILGen/mangling_inverse_generics.swift

@@ -285,18 +285,30 @@ public struct E<T: ~Copyable>: ~Copyable {
   public func __existential2__(_ t: consuming any ~Copyable) {}
 
   // DEMANGLED: test.E.something<A>() -> A1
-  // CHECK: sil [ossa] @$s4test1EV9somethingqd__ylF : $@convention(method) <T><U where U : ~Copyable> (@guaranteed E<T>) -> @out U {
+  // CHECK: sil [ossa] @$s4test1EV9somethingqd__ylF : $@convention(method) <T where T : ~Copyable><U where U : ~Copyable> (@guaranteed E<T>) -> @out U {
   @_preInverseGenerics
   public func something<U: ~Copyable>() -> U {
     fatalError()
   }
 
   // DEMANGLED: (extension in test):test.E< where A: ~Swift.Copyable>.something<A>() -> A1
-  // CHECK: sil [ossa] @$s4test1EVAARi_zrlE9somethingqd__ylF : $@convention(method) <T><U> (@guaranteed E<T>) -> @out U {
+  // CHECK: sil [ossa] @$s4test1EVAARi_zrlE9somethingqd__ylF : $@convention(method) <T where T : ~Copyable><U> (@guaranteed E<T>) -> @out U {
   public func something<U>() -> U {
     fatalError()
   }
 
+  // DEMANGLED: test.E.something2<A>() -> A1
+  // CHECK: sil [ossa] @$s4test1EV10something2qd__ylF : $@convention(method) <T><U> (@guaranteed E<T>) -> @out U {
+  public func something2<U>() -> U where T: Copyable {
+    fatalError()
+  }
+
+  // DEMANGLED: test.E.something2<A where A1: ~Swift.Copyable>() -> A1
+  // CHECK: sil [ossa] @$s4test1EV10something2qd__yRi_d__lF : $@convention(method) <T><U where U : ~Copyable> (@guaranteed E<T>) -> @out U {
+  public func something2<U: ~Copyable>() -> U where T: Copyable {
+    fatalError()
+  }
+
   // DEMANGLED: variable initialization expression of test.E.property : Swift.Int
   // CHECK: sil [transparent] [ossa] @$s4test1EV8propertySivpfi : $@convention(thin) <T where T : ~Copyable> () -> Int {
 

test/api-digester/Outputs/stability-stdlib-source-x86_64.swift.expected

@@ -314,32 +314,34 @@ TypeAlias UnsafePointer.Stride has generic signature change from <Pointee> to <P
 Func FixedWidthInteger.&*(_:_:) has been added as a protocol requirement
 Accessor UnsafeBufferPointer.debugDescription.Get() has generic signature change from <Element> to <Element where Element : ~Copyable>
 Accessor UnsafeMutableBufferPointer.debugDescription.Get() has generic signature change from <Element> to <Element where Element : ~Copyable>
-Func ManagedBuffer.withUnsafeMutablePointerToElements(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBuffer.withUnsafeMutablePointerToElements(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBuffer.withUnsafeMutablePointerToElements(_:) is now without @rethrows
-Func ManagedBuffer.withUnsafeMutablePointerToHeader(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBuffer.withUnsafeMutablePointerToHeader(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBuffer.withUnsafeMutablePointerToHeader(_:) is now without @rethrows
-Func ManagedBuffer.withUnsafeMutablePointers(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBuffer.withUnsafeMutablePointers(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBuffer.withUnsafeMutablePointers(_:) is now without @rethrows
-Func ManagedBufferPointer.withUnsafeMutablePointerToElements(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBufferPointer.withUnsafeMutablePointerToElements(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBufferPointer.withUnsafeMutablePointerToElements(_:) is now without @rethrows
-Func ManagedBufferPointer.withUnsafeMutablePointerToHeader(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBufferPointer.withUnsafeMutablePointerToHeader(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBufferPointer.withUnsafeMutablePointerToHeader(_:) is now without @rethrows
-Func ManagedBufferPointer.withUnsafeMutablePointers(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, R : ~Copyable>
+Func ManagedBufferPointer.withUnsafeMutablePointers(_:) has generic signature change from <Header, Element, R> to <Header, Element, E, R where E : Swift.Error, Element : ~Copyable, R : ~Copyable>
 Func ManagedBufferPointer.withUnsafeMutablePointers(_:) is now without @rethrows
 Func Optional.flatMap(_:) has generic signature change from <Wrapped, U> to <Wrapped, E, U where E : Swift.Error, U : ~Copyable>
 Func Optional.flatMap(_:) is now without @rethrows
 Func Optional.map(_:) has generic signature change from <Wrapped, U> to <Wrapped, E, U where E : Swift.Error, U : ~Copyable>
 Func Optional.map(_:) is now without @rethrows
 Func Result.flatMap(_:) has generic signature change from <Success, Failure, NewSuccess where Failure : Swift.Error> to <Success, Failure, NewSuccess where Failure : Swift.Error, NewSuccess : ~Copyable>
+Func Result.flatMapError(_:) has generic signature change from <Success, Failure, NewFailure where Failure : Swift.Error, NewFailure : Swift.Error> to <Success, Failure, NewFailure where Failure : Swift.Error, NewFailure : Swift.Error, Success : ~Copyable>
 Func Result.flatMapError(_:) has self access kind changing from NonMutating to Consuming
 Func Result.map(_:) has generic signature change from <Success, Failure, NewSuccess where Failure : Swift.Error> to <Success, Failure, NewSuccess where Failure : Swift.Error, NewSuccess : ~Copyable>
-Func UnsafeBufferPointer.withMemoryRebound(to:_:) has generic signature change from <Element, T, Result> to <Element, T, E, Result where E : Swift.Error, T : ~Copyable, Result : ~Copyable>
+Func Result.mapError(_:) has generic signature change from <Success, Failure, NewFailure where Failure : Swift.Error, NewFailure : Swift.Error> to <Success, Failure, NewFailure where Failure : Swift.Error, NewFailure : Swift.Error, Success : ~Copyable>
+Func UnsafeBufferPointer.withMemoryRebound(to:_:) has generic signature change from <Element, T, Result> to <Element, T, E, Result where E : Swift.Error, Element : ~Copyable, T : ~Copyable, Result : ~Copyable>
 Func UnsafeBufferPointer.withMemoryRebound(to:_:) is now without @rethrows
-Func UnsafeMutableBufferPointer.withMemoryRebound(to:_:) has generic signature change from <Element, T, Result> to <Element, T, E, Result where E : Swift.Error, T : ~Copyable, Result : ~Copyable>
+Func UnsafeMutableBufferPointer.withMemoryRebound(to:_:) has generic signature change from <Element, T, Result> to <Element, T, E, Result where E : Swift.Error, Element : ~Copyable, T : ~Copyable, Result : ~Copyable>
 Func UnsafeMutableBufferPointer.withMemoryRebound(to:_:) is now without @rethrows
-Func UnsafeMutablePointer.withMemoryRebound(to:capacity:_:) has generic signature change from <Pointee, T, Result> to <Pointee, T, E, Result where E : Swift.Error, T : ~Copyable, Result : ~Copyable>
+Func UnsafeMutablePointer.withMemoryRebound(to:capacity:_:) has generic signature change from <Pointee, T, Result> to <Pointee, T, E, Result where E : Swift.Error, Pointee : ~Copyable, T : ~Copyable, Result : ~Copyable>
 Func UnsafeMutablePointer.withMemoryRebound(to:capacity:_:) is now without @rethrows
-Func UnsafePointer.withMemoryRebound(to:capacity:_:) has generic signature change from <Pointee, T, Result> to <Pointee, T, E, Result where E : Swift.Error, T : ~Copyable, Result : ~Copyable>
+Func UnsafePointer.withMemoryRebound(to:capacity:_:) has generic signature change from <Pointee, T, Result> to <Pointee, T, E, Result where E : Swift.Error, Pointee : ~Copyable, T : ~Copyable, Result : ~Copyable>
 Func UnsafePointer.withMemoryRebound(to:capacity:_:) is now without @rethrows
 Func withExtendedLifetime(_:_:) has generic signature change from <T, Result> to <T, E, Result where E : Swift.Error, T : ~Copyable, Result : ~Copyable>
 Func withExtendedLifetime(_:_:) is now without @rethrows