From dd868cf280b9a23ca8e3f0a8a1598131040af05a Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Mon, 29 Apr 2024 15:30:27 -0700
Subject: [PATCH 1/3] Demangler: Add option to omit closure signatures

---
 include/swift/Demangling/Demangle.h |  1 +
 lib/Demangling/NodePrinter.cpp      | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/swift/Demangling/Demangle.h b/include/swift/Demangling/Demangle.h
index e76f78a5b972a..cb398d25b676d 100644
--- a/include/swift/Demangling/Demangle.h
+++ b/include/swift/Demangling/Demangle.h
@@ -63,6 +63,7 @@ struct DemangleOptions {
   bool DisplayObjCModule = true;
   bool PrintForTypeName = false;
   bool ShowAsyncResumePartial = true;
+  bool ShowClosureSignature = true;
 
   /// If this is nonempty, entities in this module name will not be qualified.
   llvm::StringRef HidingCurrentModule;
diff --git a/lib/Demangling/NodePrinter.cpp b/lib/Demangling/NodePrinter.cpp
index 7b683d7530211..58d779af6c879 100644
--- a/lib/Demangling/NodePrinter.cpp
+++ b/lib/Demangling/NodePrinter.cpp
@@ -1349,6 +1349,17 @@ static bool needSpaceBeforeType(NodePointer Type) {
   }
 }
 
+static bool shouldShowEntityType(Node::Kind EntityKind,
+                                 const DemangleOptions &Options) {
+  switch (EntityKind) {
+  case Node::Kind::ExplicitClosure:
+  case Node::Kind::ImplicitClosure:
+    return Options.ShowClosureSignature;
+  default:
+    return true;
+  }
+}
+
 NodePointer NodePrinter::print(NodePointer Node, unsigned depth,
                                bool asPrefixContext) {
   if (depth > NodePrinter::MaxDepth) {
@@ -3492,7 +3503,7 @@ NodePointer NodePrinter::printEntity(NodePointer Entity, unsigned depth,
         Printer << " : ";
         printEntityType(Entity, type, genericFunctionTypeList, depth);
       }
-    } else {
+    } else if (shouldShowEntityType(Entity->getKind(), Options)) {
       assert(TypePr == TypePrinting::FunctionStyle);
       if (MultiWordName || needSpaceBeforeType(type))
         Printer << ' ';

From aeb9039b3ab0b31b5b41c5b020cc7d3aa425159e Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Tue, 30 Apr 2024 08:11:29 -0700
Subject: [PATCH 2/3] Document shouldShowEntityType

---
 lib/Demangling/NodePrinter.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/Demangling/NodePrinter.cpp b/lib/Demangling/NodePrinter.cpp
index 58d779af6c879..701299187dfba 100644
--- a/lib/Demangling/NodePrinter.cpp
+++ b/lib/Demangling/NodePrinter.cpp
@@ -1349,11 +1349,17 @@ static bool needSpaceBeforeType(NodePointer Type) {
   }
 }
 
+/// Determine whether to print an entity's type.
 static bool shouldShowEntityType(Node::Kind EntityKind,
                                  const DemangleOptions &Options) {
   switch (EntityKind) {
   case Node::Kind::ExplicitClosure:
   case Node::Kind::ImplicitClosure:
+    /// The signature of a closure (its `Type` node) can optionally be omitted.
+    /// Unlike functions which can have overloads, the signature of a closure is
+    /// not needed to be uniquely identified. A closure is uniquely identified
+    /// by its index and parent. Omitting the signature improves the readability
+    /// when long type names are in use.
     return Options.ShowClosureSignature;
   default:
     return true;

From a171a8f17ddf60b41d400799a18864f716e6a692 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com@gmail.com>
Date: Tue, 30 Apr 2024 08:12:08 -0700
Subject: [PATCH 3/3] Add test

---
 test/Demangle/demangle-special-options.test | 3 +++
 tools/swift-demangle/swift-demangle.cpp     | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/test/Demangle/demangle-special-options.test b/test/Demangle/demangle-special-options.test
index 4d3ab0b3c874e..f6e1e00c789df 100644
--- a/test/Demangle/demangle-special-options.test
+++ b/test/Demangle/demangle-special-options.test
@@ -16,3 +16,6 @@ LOCAL: ByteBuffer #1 in closure #6
 
 RUN: swift-demangle -display-local-name-contexts=false s1a4mainyyFySRys5UInt8VGXEfU4_10ByteBufferL_aD | %FileCheck %s --check-prefix=NOLOCAL
 NOLOCAL: {{ ByteBuffer$}}
+
+RUN: swift-demangle -show-closure-signature=false s4mainySiXEfU_ySiXEfU_ | %FileCheck %s --check-prefix=CLOSURE
+CLOSURE: closure #1 in closure #1 in main
diff --git a/tools/swift-demangle/swift-demangle.cpp b/tools/swift-demangle/swift-demangle.cpp
index 35e25378ecd16..f3cff2ba3c9ca 100644
--- a/tools/swift-demangle/swift-demangle.cpp
+++ b/tools/swift-demangle/swift-demangle.cpp
@@ -94,6 +94,11 @@ static llvm::cl::opt<std::string> HidingModule(
     "hiding-module",
     llvm::cl::desc("Don't qualify types originating from this module"),
     llvm::cl::Hidden);
+
+static llvm::cl::opt<bool>
+    ShowClosureSignature("show-closure-signature", llvm::cl::init(true),
+                         llvm::cl::desc("Show type signature of closures"),
+                         llvm::cl::Hidden);
 /// \}
 
 
@@ -390,6 +395,7 @@ int main(int argc, char **argv) {
   options.DisplayObjCModule = DisplayObjCModule;
   options.HidingCurrentModule = HidingModule;
   options.DisplayLocalNameContexts = DisplayLocalNameContexts;
+  options.ShowClosureSignature = ShowClosureSignature;
 
   if (InputNames.empty()) {
     CompactMode = true;