SIL: Update lowerCaptureContextParameters() for PackElementExpr captures

Author: slavapestov

lib/SIL/IR/SILFunctionType.cpp

@@ -1970,33 +1970,39 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       continue;
     }
 
-    auto *varDecl = cast<VarDecl>(capture.getDecl());
+    auto options = SILParameterInfo::Options();
+
+    Type type;
+    VarDecl *varDecl = nullptr;
+    if (auto *expr = capture.getPackElement()) {
+      type = expr->getType();
+    } else {
+      varDecl = cast<VarDecl>(capture.getDecl());
+      type = varDecl->getTypeInContext();
+
+      // If we're capturing a parameter pack, wrap it in a tuple.
+      if (type->is<PackExpansionType>()) {
+        assert(!cast<ParamDecl>(varDecl)->supportsMutation() &&
+               "Cannot capture a pack as an lvalue");
+
+        SmallVector<TupleTypeElt, 1> elts;
+        elts.push_back(type);
+        type = TupleType::get(elts, TC.Context);
+      }
+
+      if (isolatedParam == varDecl) {
+        options |= SILParameterInfo::Isolated;
+        isolatedParam = nullptr;
+      }
+    }
 
-    auto type = varDecl->getTypeInContext();
     assert(!type->hasLocalArchetype() ||
            (genericSig && origGenericSig &&
             !genericSig->isEqual(origGenericSig)));
     type = mapTypeOutOfContext(type);
 
     auto canType = type->getReducedType(
         genericSig ? genericSig : origGenericSig);
-
-    auto options = SILParameterInfo::Options();
-    if (isolatedParam == varDecl) {
-      options |= SILParameterInfo::Isolated;
-      isolatedParam = nullptr;
-    }
-
-    // If we're capturing a parameter pack, wrap it in a tuple.
-    if (isa<PackExpansionType>(canType)) {
-      assert(!cast<ParamDecl>(varDecl)->supportsMutation() &&
-             "Cannot capture a pack as an lvalue");
-
-      SmallVector<TupleTypeElt, 1> elts;
-      elts.push_back(canType);
-      canType = CanTupleType(TupleType::get(elts, TC.Context));
-    }
-
     auto &loweredTL =
         TC.getTypeLowering(AbstractionPattern(genericSig, canType), canType,
                            expansion);
@@ -2018,6 +2024,8 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       break;
     }
     case CaptureKind::Box: {
+      assert(varDecl);
+
       // The type in the box is lowered in the minimal context.
       auto minimalLoweredTy =
           TC.getTypeLowering(AbstractionPattern(genericSig, canType), canType,
@@ -2035,6 +2043,8 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       break;
     }
     case CaptureKind::ImmutableBox: {
+      assert(varDecl);
+
       // The type in the box is lowered in the minimal context.
       auto minimalLoweredTy =
           TC.getTypeLowering(AbstractionPattern(genericSig, canType), canType,

lib/SIL/IR/TypeLowering.cpp

@@ -118,6 +118,19 @@ static bool hasSingletonMetatype(CanType instanceType) {
 
 CaptureKind TypeConverter::getDeclCaptureKind(CapturedValue capture,
                                               TypeExpansionContext expansion) {
+  if (auto *expr = capture.getPackElement()) {
+    auto contextTy = expr->getType();
+    auto &lowering = getTypeLowering(
+        contextTy, TypeExpansionContext::noOpaqueTypeArchetypesSubstitution(
+                            expansion.getResilienceExpansion()));
+
+    assert(!contextTy->isNoncopyable() && "Not implemented");
+    if (!lowering.isAddressOnly())
+      return CaptureKind::Constant;
+
+    return CaptureKind::Immutable;
+  }
+
   auto decl = capture.getDecl();
   auto *var = cast<VarDecl>(decl);
   assert(var->hasStorage() &&