From 3948aedb7ab9a0626faccbe14624dbafeb2e3931 Mon Sep 17 00:00:00 2001
From: Jan Svoboda <jan_svoboda@apple.com>
Date: Wed, 17 May 2023 16:45:18 -0700
Subject: [clang] NFC: Modernize Decl iteration via IdentifierResolver

---
 clang/include/clang/Sema/IdentifierResolver.h | 11 ++++++-----
 clang/lib/Sema/IdentifierResolver.cpp         |  9 ++++++---
 clang/lib/Serialization/ASTWriter.cpp         | 21 ++++++---------------
 3 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/clang/include/clang/Sema/IdentifierResolver.h b/clang/include/clang/Sema/IdentifierResolver.h
index 7c8dc46307d4..1fbd6c48e518 100644
--- a/clang/include/clang/Sema/IdentifierResolver.h
+++ b/clang/include/clang/Sema/IdentifierResolver.h
@@ -134,13 +134,14 @@ public:
   explicit IdentifierResolver(Preprocessor &PP);
   ~IdentifierResolver();
 
-  /// begin - Returns an iterator for decls with the name 'Name'.
+  /// Returns a range of decls with the name 'Name'.
+  llvm::iterator_range<iterator> decls(DeclarationName Name);
+
+  /// Returns an iterator over decls with the name 'Name'.
   iterator begin(DeclarationName Name);
 
-  /// end - Returns an iterator that has 'finished'.
-  iterator end() {
-    return iterator();
-  }
+  /// Returns the end iterator.
+  iterator end() { return iterator(); }
 
   /// isDeclInScope - If 'Ctx' is a function/method, isDeclInScope returns true
   /// if 'D' is in Scope 'S', otherwise 'S' is ignored and isDeclInScope returns
diff --git a/clang/lib/Sema/IdentifierResolver.cpp b/clang/lib/Sema/IdentifierResolver.cpp
index 607dc3111e9d..773cef65dcbd 100644
--- a/clang/lib/Sema/IdentifierResolver.cpp
+++ b/clang/lib/Sema/IdentifierResolver.cpp
@@ -231,9 +231,12 @@ void IdentifierResolver::RemoveDecl(NamedDecl *D) {
   return toIdDeclInfo(Ptr)->RemoveDecl(D);
 }
 
-/// begin - Returns an iterator for decls with name 'Name'.
-IdentifierResolver::iterator
-IdentifierResolver::begin(DeclarationName Name) {
+llvm::iterator_range<IdentifierResolver::iterator>
+IdentifierResolver::decls(DeclarationName Name) {
+  return {begin(Name), end()};
+}
+
+IdentifierResolver::iterator IdentifierResolver::begin(DeclarationName Name) {
   if (IdentifierInfo *II = Name.getAsIdentifierInfo())
     readingIdentifier(*II);
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 8816575ba60e..749aaa4cd6e1 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -3558,12 +3558,8 @@ public:
       if (MacroOffset)
         DataLen += 4; // MacroDirectives offset.
 
-      if (NeedDecls) {
-        for (IdentifierResolver::iterator D = IdResolver.begin(II),
-                                       DEnd = IdResolver.end();
-             D != DEnd; ++D)
-          DataLen += 4;
-      }
+      if (NeedDecls)
+        DataLen += std::distance(IdResolver.begin(II), IdResolver.end()) * 4;
     }
     return emitULEBKeyDataLength(KeyLen, DataLen, Out);
   }
@@ -3608,8 +3604,7 @@ public:
       // "stat"), but the ASTReader adds declarations to the end of the list
       // (so we need to see the struct "stat" before the function "stat").
       // Only emit declarations that aren't from a chained PCH, though.
-      SmallVector<NamedDecl *, 16> Decls(IdResolver.begin(II),
-                                         IdResolver.end());
+      SmallVector<NamedDecl *, 16> Decls(IdResolver.decls(II));
       for (NamedDecl *D : llvm::reverse(Decls))
         LE.write<uint32_t>(
             Writer.getDeclID(getDeclForLocalLookup(PP.getLangOpts(), D)));
@@ -4887,13 +4882,9 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
     }
     // Sort the identifiers to visit based on their name.
     llvm::sort(IIs, llvm::deref<std::less<>>());
-    for (const IdentifierInfo *II : IIs) {
-      for (IdentifierResolver::iterator D = SemaRef.IdResolver.begin(II),
-                                     DEnd = SemaRef.IdResolver.end();
-           D != DEnd; ++D) {
-        GetDeclRef(*D);
-      }
-    }
+    for (const IdentifierInfo *II : IIs)
+      for (const Decl *D : SemaRef.IdResolver.decls(II))
+        GetDeclRef(D);
   }
 
   // For method pool in the module, if it contains an entry for a selector,
-- 
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