ASTPrinter: Tweak PackExpansionType printing

Author: slavapestov

lib/AST/ASTPrinter.cpp

@@ -6045,12 +6045,24 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
   }
 
   void visitPackExpansionType(PackExpansionType *T) {
+    SmallVector<Type, 2> rootParameterPacks;
+    T->getPatternType()->getTypeParameterPacks(rootParameterPacks);
+
+    if (rootParameterPacks.empty() &&
+        (T->getCountType()->isParameterPack() ||
+         T->getCountType()->is<PackArchetypeType>())) {
+      Printer << "/* shape: ";
+      visit(T->getCountType());
+      Printer << " */ ";
+    }
+
     Printer << "repeat ";
+
     visit(T->getPatternType());
   }
 
   void visitPackElementType(PackElementType *T) {
-    Printer << "@level(" << T->getLevel() << ") ";
+    Printer << "/* level: " << T->getLevel() << " */ ";
     visit(T->getPackType());
   }
 

test/Constraints/pack-expansion-expressions.swift

@@ -526,8 +526,8 @@ do {
 func test_pack_expansion_to_void_conv_for_closure_result<each T>(x: repeat each T) {
   let _: () -> Void = { repeat print(each x) } // Ok
   let _: () -> Void = { (repeat print(each x)) } // Ok
-  let _: (Int) -> Void = { repeat ($0, print(each x)) } // expected-warning {{'repeat (Int, ())' is unused}}
-  let _: (Int, String) -> Void = { ($0, repeat ($1, print(each x))) } // expected-warning {{'(Int, repeat (String, ()))' is unused}}
+  let _: (Int) -> Void = { repeat ($0, print(each x)) } // expected-warning {{expression of type '/* shape: each T */ repeat (Int, ())' is unused}}
+  let _: (Int, String) -> Void = { ($0, repeat ($1, print(each x))) } // expected-warning {{expression of type '(Int, /* shape: each T */ repeat (String, ()))' is unused}}
 }
 
 // rdar://109539394 - crash on passing multiple variadic lists to singly variadic callee

test/SILGen/variadic-generic-tuples.swift

@@ -13,7 +13,7 @@ func takeAny(_ arg: Any) {}
 // CHECK-NEXT:    [[IDX_EQ_LEN:%.*]] = builtin "cmp_eq_Word"([[IDX]] : $Builtin.Word, [[LEN]] : $Builtin.Word) : $Builtin.Int1
 // CHECK-NEXT:     cond_br [[IDX_EQ_LEN]], bb3, bb2
 // CHECK:       bb2:
-// CHECK-NEXT:    [[INDEX:%.*]] = dynamic_pack_index [[IDX]] of $Pack{repeat ()}
+// CHECK-NEXT:    [[INDEX:%.*]] = dynamic_pack_index [[IDX]] of $Pack{/* shape: each T */ repeat ()}
 // CHECK-NEXT:    open_pack_element [[INDEX]] of <each T> at <Pack{repeat each T}>, shape $each T, uuid [[UUID:".*"]]
 // CHECK-NEXT:    [[TEMP:%.*]] = alloc_stack $Any
 // CHECK-NEXT:    [[ELT_ADDR:%.*]] = pack_element_get [[INDEX]] of %0 : $*Pack{repeat each T} as $*@pack_element([[UUID]]) each T