From 66bd5d79891ddb8bf0d31d78c4973f6d20dcb571 Mon Sep 17 00:00:00 2001
From: Jonas Hahnfeld <jonas.hahnfeld@cern.ch>
Date: Wed, 14 Aug 2024 15:11:04 +0200
Subject: [PATCH] [clang-repl] Fix PCH with delayed template parsing (#103028)

When instantiating a delayed template, the recorded token stream is
passed to `Parser::ParseLateTemplatedFuncDef` which will append the
current token "so it doesn't get lost". With incremental extensions
enabled, this is `repl_input_end` which subsequently needs support for
(de)serialization.
---
 clang/lib/Serialization/ASTReader.cpp         |  1 +
 clang/lib/Serialization/ASTWriter.cpp         |  1 +
 .../delayed-template-parsing-pch.cpp          | 25 +++++++++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 clang/test/Interpreter/delayed-template-parsing-pch.cpp

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 511e2df7ad323..fa9b815239dbb 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1887,6 +1887,7 @@ Token ASTReader::ReadToken(ModuleFile &M, const RecordDataImpl &Record,
     case tok::annot_pragma_unused:
     case tok::annot_pragma_openacc:
     case tok::annot_pragma_openacc_end:
+    case tok::annot_repl_input_end:
       break;
     default:
       llvm_unreachable("missing deserialization code for annotation token");
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 1455f8e4145cb..5cfb98c2a1060 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4734,6 +4734,7 @@ void ASTWriter::AddToken(const Token &Tok, RecordDataImpl &Record) {
     case tok::annot_pragma_unused:
     case tok::annot_pragma_openacc:
     case tok::annot_pragma_openacc_end:
+    case tok::annot_repl_input_end:
       break;
     default:
       llvm_unreachable("missing serialization code for annotation token");
diff --git a/clang/test/Interpreter/delayed-template-parsing-pch.cpp b/clang/test/Interpreter/delayed-template-parsing-pch.cpp
new file mode 100644
index 0000000000000..f3bd4649ed034
--- /dev/null
+++ b/clang/test/Interpreter/delayed-template-parsing-pch.cpp
@@ -0,0 +1,25 @@
+// Test the setup without incremental extensions first
+// RUN: %clang_cc1 -std=c++17 -fdelayed-template-parsing -fpch-instantiate-templates %s -emit-pch -o %t.pch -verify
+// RUN: %clang_cc1 -std=c++17 -fdelayed-template-parsing -include-pch %t.pch %s -verify
+
+// RUN: %clang_cc1 -std=c++17 -fdelayed-template-parsing -fincremental-extensions -fpch-instantiate-templates %s -emit-pch -o %t.incremental.pch -verify
+// RUN: %clang_cc1 -std=c++17 -fdelayed-template-parsing -fincremental-extensions -include-pch %t.incremental.pch %s -verify
+
+// expected-no-diagnostics
+
+#ifndef PCH
+#define PCH
+
+// Have one template that is instantiated in the PCH (via the passed option
+// -fpch-instantiate-templates) and then serialized
+template <typename T> T ft1() { return 0; }
+inline int f1() { return ft1<int>(); }
+
+// Have a second late-parsed template that needs to be deserialized
+template <typename T> T ft2() { return 0; }
+
+#else
+
+int f2() { return ft2<int>(); }
+
+#endif