From c1b3f2594d79573f36d123627b92c2ff1fbca27e Mon Sep 17 00:00:00 2001
From: Axel Naumann <Axel.Naumann@cern.ch>
Date: Fri, 24 Nov 2023 17:10:18 +0100
Subject: [PATCH] [cling] Support bare `#` in input line:

fixes #11190.
---
 .../lib/MetaProcessor/InputValidator.cpp      | 22 ++++++++++---------
 .../cling/lib/MetaProcessor/MetaLexer.cpp     |  7 ++++++
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/interpreter/cling/lib/MetaProcessor/InputValidator.cpp b/interpreter/cling/lib/MetaProcessor/InputValidator.cpp
index 9c0dba3aaea25c..e6543ca3649503 100644
--- a/interpreter/cling/lib/MetaProcessor/InputValidator.cpp
+++ b/interpreter/cling/lib/MetaProcessor/InputValidator.cpp
@@ -82,17 +82,19 @@ namespace cling {
       case tok::hash:
         Lex.SkipWhitespace();
         Lex.LexAnyString(Tok);
-        const llvm::StringRef PPtk = Tok.getIdent();
-        if (PPtk.startswith("if")) {
-          m_ParenStack.push_back(tok::hash);
-        } else if (PPtk.startswith("endif") &&
-                   (PPtk.size() == 5 || PPtk[5]=='/' || isspace(PPtk[5]))) {
-            if (m_ParenStack.empty() || m_ParenStack.back() != tok::hash)
-              Res = kMismatch;
-            else
-              m_ParenStack.pop_back();
+        if (Tok.isNot(tok::eof)) {
+          const llvm::StringRef PPtk = Tok.getIdent();
+          if (PPtk.startswith("if")) {
+            m_ParenStack.push_back(tok::hash);
+          } else if (PPtk.startswith("endif") &&
+                    (PPtk.size() == 5 || PPtk[5]=='/' || isspace(PPtk[5]))) {
+              if (m_ParenStack.empty() || m_ParenStack.back() != tok::hash)
+                Res = kMismatch;
+              else
+                m_ParenStack.pop_back();
+          }
+          break;
         }
-        break;
       }
     } while (Tok.isNot(tok::eof) && Res != kMismatch);
 
diff --git a/interpreter/cling/lib/MetaProcessor/MetaLexer.cpp b/interpreter/cling/lib/MetaProcessor/MetaLexer.cpp
index 03c1bc08e14fdc..5fcc80133b77e3 100644
--- a/interpreter/cling/lib/MetaProcessor/MetaLexer.cpp
+++ b/interpreter/cling/lib/MetaProcessor/MetaLexer.cpp
@@ -102,6 +102,13 @@ namespace cling {
   void MetaLexer::LexAnyString(Token& Tok) {
     Tok.startToken(curPos);
     // consume until we reach one of the "AnyString" delimiters or EOF.
+    if (*curPos == '\0') {
+      Tok.setBufStart(curPos);
+      Tok.setKind(tok::eof);
+      Tok.setLength(0);
+      return;
+    }
+
     while(*curPos != ' ' && *curPos != '\t' && *curPos != '\0') {
       curPos++;
     }