From f3cccd06d3d6b836bd8f9c4d16139fafceeea70a Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Tue, 5 Mar 2024 17:56:52 +0100
Subject: [PATCH] Fix #12486 Improve simplification of using statements (#6080)

---
 lib/tokenize.cpp              | 21 +++++++++++----
 test/testsimplifytemplate.cpp |  2 +-
 test/testsimplifyusing.cpp    | 49 +++++++++++++++++++++++++++++------
 3 files changed, 58 insertions(+), 14 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index eea73d69248..953de6f64b1 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -2845,13 +2845,21 @@ bool Tokenizer::simplifyUsing()
         if (!Token::Match(tok, "using ::| %name% ::"))
             continue;
         Token* end = tok->tokAt(3);
-        while (end && end->str() != ";")
-            end = end->next();
+        while (end && !Token::Match(end, "[;,]")) {
+            if (end->str() == "<" && end->link()) // skip template args
+                end = end->link()->next();
+            else
+                end = end->next();
+        }
         if (!end)
             continue;
-        if (!end->tokAt(-1)->isNameOnly()) // e.g. operator=
+        if (!end->tokAt(-1)->isNameOnly() || end->tokAt(-2)->isLiteral()) // e.g. operator=, operator""sv
             continue;
-        tok->insertToken(end->strAt(-1))->insertToken("=");
+        tok->insertToken(end->strAt(-1))->insertToken("=")->isSimplifiedTypedef(true);
+        if (end->str() == ",") { // comma-separated list
+            end->str(";");
+            end->insertToken("using");
+        }
         tok = end;
     }
 
@@ -2922,8 +2930,11 @@ bool Tokenizer::simplifyUsing()
         std::string scope = currentScope->fullName;
         Token *usingStart = tok;
         Token *start;
-        if (tok->strAt(2) == "=")
+        if (tok->strAt(2) == "=") {
+            if (currentScope->type == ScopeInfo3::Record && tok->tokAt(2)->isSimplifiedTypedef())  // don't simplify within class definition
+                continue;
             start = tok->tokAt(3);
+        }
         else
             start = tok->linkAt(2)->tokAt(3);
         Token *usingEnd = findSemicolon(start);
diff --git a/test/testsimplifytemplate.cpp b/test/testsimplifytemplate.cpp
index 152281a4ebc..951d1aa23cf 100644
--- a/test/testsimplifytemplate.cpp
+++ b/test/testsimplifytemplate.cpp
@@ -2880,7 +2880,7 @@ class TestSimplifyTemplate : public TestFixture {
                            "struct f<b::B<0>> ; "
                            "} "
                            "} "
-                           "b :: f<b::B<0>> g1 ; struct b :: B<0> { } ; "
+                           "b :: f<b::B<0>> g1 ; struct b :: B<0> { using d = B<0> :: d ; } ; "
                            "struct b :: f<b::B<0>> { } ;";
         ASSERT_EQUALS(exp, tok(code));
     }
diff --git a/test/testsimplifyusing.cpp b/test/testsimplifyusing.cpp
index f1a3ff49a94..abf15dd0048 100644
--- a/test/testsimplifyusing.cpp
+++ b/test/testsimplifyusing.cpp
@@ -683,14 +683,47 @@ class TestSimplifyUsing : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
-    void simplifyUsing30() { // #8454
-        const char code[] = "using std::to_string;\n"
-                            "void f() {\n"
-                            "    std::string str = to_string(1);\n"
-                            "}\n";
-        const char expected[] = "void f ( ) { std :: string str ; str = std :: to_string ( 1 ) ; }";
-        ASSERT_EQUALS(expected, tok(code, Platform::Type::Native, /*debugwarnings*/ true));
-        ASSERT_EQUALS("", errout.str());
+    void simplifyUsing30() {
+        {
+            const char code[] = "using std::to_string;\n" // #8454
+                                "void f() {\n"
+                                "    std::string str = to_string(1);\n"
+                                "}\n";
+            const char expected[] = "void f ( ) { std :: string str ; str = std :: to_string ( 1 ) ; }";
+            ASSERT_EQUALS(expected, tok(code, Platform::Type::Native, /*debugwarnings*/ true));
+            ASSERT_EQUALS("", errout.str());
+        }
+        {
+            const char code[] = "using std::cout, std::endl, std::cerr, std::ostringstream;\n"
+                                "cerr << \"abc\";\n";
+            const char expected[] = "std :: cerr << \"abc\" ;";
+            ASSERT_EQUALS(expected, tok(code, Platform::Type::Native, /*debugwarnings*/ true));
+            ASSERT_EQUALS("", errout.str());
+        }
+        {
+            const char code[] = "using std::string_view_literals::operator\"\"sv;\n";
+            const char expected[] = "using std :: string_view_literals :: operator\"\"sv ;";
+            ASSERT_EQUALS(expected, tok(code, Platform::Type::Native, /*debugwarnings*/ true));
+            ASSERT_EQUALS("", errout.str());
+        }
+        {
+            const char code[] = "template <typename T>\n"
+                                "class vector : public ::std::vector<T> {\n"
+                                "public:\n"
+                                "    using ::std::vector<T>::vector;\n"
+                                "    vector() {}\n"
+                                "};\n"
+                                "vector <int> v;\n";
+            const char expected[] = "class vector<int> ; "
+                                    "vector<int> v ; "
+                                    "class vector<int> : public :: std :: vector<int> { "
+                                    "public: "
+                                    "using vector<int> = :: std :: vector<int> :: vector<int> ; "
+                                    "vector<int> ( ) { } "
+                                    "} ;";
+            ASSERT_EQUALS(expected, tok(code, Platform::Type::Native, /*debugwarnings*/ true));
+            ASSERT_EQUALS("", errout.str());
+        }
     }
 
     void simplifyUsing8970() {