[libcxxabi] [llvm] Update stale comments of the demangler, NFC (PR #91740)

[Haojian Wu via llvm-commits]

https://github.com/hokein created https://github.com/llvm/llvm-project/pull/91740

To reflect what the actual code does.

>From dfb22c376fffe838b9f35f2f23f32d9cfbc94b88 Mon Sep 17 00:00:00 2001
From: Haojian Wu <hokein.wu at gmail.com>
Date: Fri, 10 May 2024 15:21:08 +0200
Subject: [PATCH] Update stale comments of the demangler, NFC

To reflect what the actual code does.
---
 libcxxabi/src/demangle/ItaniumDemangle.h     | 3 ++-
 llvm/include/llvm/Demangle/ItaniumDemangle.h | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/libcxxabi/src/demangle/ItaniumDemangle.h b/libcxxabi/src/demangle/ItaniumDemangle.h
index 4a0444d407ea7..36bf454636366 100644
--- a/libcxxabi/src/demangle/ItaniumDemangle.h
+++ b/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -5715,6 +5715,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParam() {
 }
 
 // <template-param-decl> ::= Ty                          # type parameter
+//                       ::= Tk <concept name> [<template-args>] # constrained type parameter
 //                       ::= Tn <type>                   # non-type parameter
 //                       ::= Tt <template-param-decl>* E # template parameter
 //                       ::= Tp <template-param-decl>    # parameter pack
@@ -5846,7 +5847,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseTemplateArg() {
   }
 }
 
-// <template-args> ::= I <template-arg>* E
+// <template-args> ::= I <template-arg>* [Q <requires-clause expr>] E
 //     extension, the abi says <template-arg>+
 template <typename Derived, typename Alloc>
 Node *
diff --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
index d33af157543fe..e7c008be32f9e 100644
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -5714,6 +5714,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParam() {
 }
 
 // <template-param-decl> ::= Ty                          # type parameter
+//                       ::= Tk <concept name> [<template-args>] # constrained type parameter
 //                       ::= Tn <type>                   # non-type parameter
 //                       ::= Tt <template-param-decl>* E # template parameter
 //                       ::= Tp <template-param-decl>    # parameter pack
@@ -5845,7 +5846,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseTemplateArg() {
   }
 }
 
-// <template-args> ::= I <template-arg>* E
+// <template-args> ::= I <template-arg>* [Q <requires-clause expr>] E
 //     extension, the abi says <template-arg>+
 template <typename Derived, typename Alloc>
 Node *