From 112b1573c566e26e3c6f77904fe216230b1121b4 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Wed, 18 May 2022 13:52:44 +0200
Subject: [PATCH] Fix #11078 FN constructing string from nullptr / #11079 FN
 unread variables (#4112)

* Fix #11078 FN constructing string from nullptr / #11079 FN unread variables

* Format
---
 lib/checknullpointer.cpp |  8 ++++----
 lib/checkunusedvar.cpp   |  4 +++-
 test/testnullpointer.cpp |  9 +++++++++
 test/testunusedvar.cpp   | 23 +++++++++++++++++++++++
 4 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 62ff03ba0..56d256b0b 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -215,9 +215,9 @@ bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown, const Set
         return true;
 
     // std::string dereferences nullpointers
-    if (Token::Match(parent->tokAt(-3), "std :: string|wstring (") && tok->strAt(1) == ")")
+    if (Token::Match(parent->tokAt(-3), "std :: string|wstring (|{ %name% )|}"))
         return true;
-    if (Token::Match(parent->previous(), "%name% (") && tok->strAt(1) == ")") {
+    if (Token::Match(parent->previous(), "%name% (|{ %name% )|}")) {
         const Variable* var = tok->tokAt(-2)->variable();
         if (var && !var->isPointer() && !var->isArray() && var->isStlStringType())
             return true;
@@ -350,8 +350,8 @@ void CheckNullPointer::nullConstantDereference()
             else if (Token::Match(tok, "0 [") && (tok->previous()->str() != "&" || !Token::Match(tok->next()->link()->next(), "[.(]")))
                 nullPointerError(tok);
 
-            else if (Token::Match(tok->previous(), "!!. %name% (") && (tok->previous()->str() != "::" || tok->strAt(-2) == "std")) {
-                if (Token::Match(tok->tokAt(2), "0|NULL|nullptr )") && tok->varId()) { // constructor call
+            else if (Token::Match(tok->previous(), "!!. %name% (|{") && (tok->previous()->str() != "::" || tok->strAt(-2) == "std")) {
+                if (Token::Match(tok->tokAt(2), "0|NULL|nullptr )|}") && tok->varId()) { // constructor call
                     const Variable *var = tok->variable();
                     if (var && !var->isPointer() && !var->isArray() && var->isStlStringType())
                         nullPointerError(tok);
diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
index 9a4db1f99..36455a0ad 100644
--- a/lib/checkunusedvar.cpp
+++ b/lib/checkunusedvar.cpp
@@ -1198,6 +1198,8 @@ void CheckUnusedVar::checkFunctionVariableUsage()
             if (tok->str() == "=" && isRaiiClass(tok->valueType(), mTokenizer->isCPP(), false))
                 continue;
 
+            const bool isPointer = tok->valueType() && tok->valueType()->pointer;
+
             if (tok->isName()) {
                 if (isRaiiClass(tok->valueType(), mTokenizer->isCPP(), false))
                     continue;
@@ -1213,7 +1215,7 @@ void CheckUnusedVar::checkFunctionVariableUsage()
                     continue;
             }
             // Do not warn about assignment with NULL
-            if (isNullOperand(tok->astOperand2()))
+            if (isPointer && isNullOperand(tok->astOperand2()))
                 continue;
 
             if (!tok->astOperand1())
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index c01f1a4a7..f2705009d 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -3588,6 +3588,15 @@ private:
               "  return s;\n"
               "}\n", /*inconclusive*/ true);
         ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n" // #11078
+              "    const char* p = nullptr;\n"
+              "    std::string s1{ p };\n"
+              "    std::string s2{ nullptr };\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (error) Null pointer dereference: p\n"
+                      "[test.cpp:4]: (error) Null pointer dereference\n",
+                      errout.str());
     }
 
     void nullpointerStdStream() {
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
index 53ac45bd3..666e85bc2 100644
--- a/test/testunusedvar.cpp
+++ b/test/testunusedvar.cpp
@@ -5961,6 +5961,29 @@ private:
                               "    p = (Foo *)NULL;\n"
                               "}");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("void f() {\n" // #11079
+                              "    std::string s1{ nullptr };\n"
+                              "    std::string s2{ NULL };\n"
+                              "    std::string s4(nullptr);\n"
+                              "    std::string s5(NULL);\n"
+                              "}\n"
+                              "struct A { A(void*) {} };\n"
+                              "static void g() {\n"
+                              "    A a1{ nullptr };\n"
+                              "    A a2{ NULL };\n"
+                              "    A a4(nullptr);\n"
+                              "    A a5(NULL);\n"
+                              "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (style) Variable 's1' is assigned a value that is never used.\n"
+                      "[test.cpp:3]: (style) Variable 's2' is assigned a value that is never used.\n"
+                      "[test.cpp:4]: (style) Variable 's4' is assigned a value that is never used.\n"
+                      "[test.cpp:5]: (style) Variable 's5' is assigned a value that is never used.\n"
+                      "[test.cpp:9]: (style) Variable 'a1' is assigned a value that is never used.\n"
+                      "[test.cpp:10]: (style) Variable 'a2' is assigned a value that is never used.\n"
+                      "[test.cpp:11]: (style) Variable 'a4' is assigned a value that is never used.\n"
+                      "[test.cpp:12]: (style) Variable 'a5' is assigned a value that is never used.\n",
+                      errout.str());
     }
 
     void localvarUnusedGoto() {