SIL: Refactor type lowering computation of the effective generic signature

This also fixes a long-standing bug with default argument expressions
capturing generic parameters.

Author: slavapestov

include/swift/SIL/TypeLowering.h

@@ -844,10 +844,13 @@ class TypeConverter {
   /// Returns the formal type, lowered AST type, and SILFunctionType
   /// for a constant reference.
   const SILConstantInfo &getConstantInfo(SILDeclRef constant);
-  
+
+  /// Get the generic environment for a constant.
+  GenericSignature *getConstantGenericSignature(SILDeclRef constant);
+
   /// Get the generic environment for a constant.
   GenericEnvironment *getConstantGenericEnvironment(SILDeclRef constant);
-  
+
   /// Returns the SIL type of a constant reference.
   SILType getConstantType(SILDeclRef constant) {
     return getConstantInfo(constant).getSILType();
@@ -944,17 +947,6 @@ class TypeConverter {
   SILType getSubstitutedStorageType(AbstractStorageDecl *value,
                                     Type lvalueType);
 
-  /// Retrieve the set of archetypes closed over by the given function.
-  GenericEnvironment *getEffectiveGenericEnvironment(AnyFunctionRef fn,
-                                                     CaptureInfo captureInfo);
-
-  /// Retrieve the set of generic parameters closed over by the given function.
-  CanGenericSignature getEffectiveGenericSignature(AnyFunctionRef fn,
-                                                   CaptureInfo captureInfo);
-
-  /// Retrieve the set of generic parameters closed over by the context.
-  CanGenericSignature getEffectiveGenericSignature(DeclContext *dc);
-
   /// Push a generic function context. See GenericContextScope for an RAII
   /// interface to this function.
   ///

lib/AST/ASTDumper.cpp

@@ -988,9 +988,17 @@ namespace {
       if (P->isAutoClosure())
         OS << " autoclosure";
 
-      if (P->getDefaultArgumentKind() != DefaultArgumentKind::None)
+      if (P->getDefaultArgumentKind() != DefaultArgumentKind::None) {
         printField("default_arg",
                    getDefaultArgumentKindString(P->getDefaultArgumentKind()));
+      }
+
+      if (P->getDefaultValue() &&
+        !P->getDefaultArgumentCaptureInfo().isTrivial()) {
+        OS << " ";
+        P->getDefaultArgumentCaptureInfo().print(
+          PrintWithColorRAII(OS, CapturesColor).getOS());
+      }
 
       if (auto init = P->getDefaultValue()) {
         OS << " expression=\n";