From 5a21851bb7943fb29268043209d1a8e4e2780396 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Thu, 14 Sep 2023 12:14:08 +0200
Subject: [PATCH] Fix #11981 internalAstError with using declaration (#5446)

---
 lib/tokenize.cpp           | 15 ++++++++++++---
 test/testsimplifyusing.cpp |  9 +++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index d1c5c1d04..141034fb7 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -3236,9 +3236,18 @@ bool Tokenizer::simplifyUsing()
                         }
                     }
 
-                    // just replace simple type aliases
-                    TokenList::copyTokens(tok1, start, usingEnd->previous());
-                    tok1->deleteThis();
+                    // Is this a "T()" expression where T is a pointer type?
+                    if (Token::Match(tok1, "%name% ( )") && !pointers.empty()) {
+                        Token* tok2 = tok1->linkAt(1);
+                        tok1->deleteThis();
+                        TokenList::copyTokens(tok1, start, usingEnd->previous());
+                        tok2->insertToken("0");
+                        after = tok2->next();
+                    }
+                    else { // just replace simple type aliases
+                        TokenList::copyTokens(tok1, start, usingEnd->previous());
+                        tok1->deleteThis();
+                    }
                     substitute = true;
                 }
             } else {
diff --git a/test/testsimplifyusing.cpp b/test/testsimplifyusing.cpp
index 02cc14aaf..33d3cb7bb 100644
--- a/test/testsimplifyusing.cpp
+++ b/test/testsimplifyusing.cpp
@@ -71,6 +71,7 @@ private:
         TEST_CASE(simplifyUsing26); // #11090
         TEST_CASE(simplifyUsing27);
         TEST_CASE(simplifyUsing28);
+        TEST_CASE(simplifyUsing29);
 
         TEST_CASE(simplifyUsing8970);
         TEST_CASE(simplifyUsing8971);
@@ -684,6 +685,14 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void simplifyUsing29() { // #11981
+        const char code[] = "using T = int*;\n"
+                            "void f(T = T()) {}\n";
+        const char expected[] = "void f ( int * = ( int * ) 0 ) { }";
+        ASSERT_EQUALS(expected, tok(code, cppcheck::Platform::Type::Native, /*debugwarnings*/ true));
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void simplifyUsing8970() {
         const char code[] = "using V = std::vector<int>;\n"
                             "struct A {\n"