From 54fbfd7c0fd0f197164904da3e5858b6ed01b718 Mon Sep 17 00:00:00 2001
From: Paul Fultz II <pfultz2@yahoo.com>
Date: Sun, 27 Mar 2022 03:02:30 -0500
Subject: [PATCH] Fix 10895: FP danglingTempReference with emplace() (#3948)

* Fix 10895: FP danglingTempReference with emplace()

* Format
---
 cfg/std.cfg                | 10 ++++++++--
 lib/checkstl.cpp           | 20 ++++++++++++++++++--
 test/testautovariables.cpp |  7 +++++++
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/cfg/std.cfg b/cfg/std.cfg
index 229725771..4f043a6ca 100644
--- a/cfg/std.cfg
+++ b/cfg/std.cfg
@@ -8223,6 +8223,10 @@ initializer list (7) string& replace (const_iterator i1, const_iterator i2, init
   </container>
   <container id="stdVector" startPattern="std :: vector &lt;" inherits="stdVectorDeque">
     <type unstable="erase insert"/>
+    <access>
+      <function name="emplace_back" action="push" yields="item"/>
+      <function name="emplace_front" action="push" yields="item"/>
+    </access>
   </container>
   <container id="stdDeque" startPattern="std :: deque &lt;" inherits="stdVectorDeque">
     <type unstable="erase insert"/>
@@ -8245,6 +8249,7 @@ initializer list (7) string& replace (const_iterator i1, const_iterator i2, init
   </container>
   <container id="stdQueue" startPattern="std :: queue|priority_queue &lt;" inherits="stdContainer">
     <access>
+      <function name="emplace" action="push" yields="item"/>
       <function name="push" action="push"/>
       <function name="pop" action="pop"/>
       <function name="front" yields="item"/>
@@ -8253,6 +8258,7 @@ initializer list (7) string& replace (const_iterator i1, const_iterator i2, init
   </container>
   <container id="stdStack" startPattern="std :: stack &lt;" inherits="stdContainer">
     <access>
+      <function name="emplace" action="push" yields="item"/>
       <function name="push" action="push"/>
       <function name="pop" action="pop"/>
       <function name="top" yields="item"/>
@@ -8304,11 +8310,11 @@ initializer list (7) string& replace (const_iterator i1, const_iterator i2, init
   <container id="stdList" startPattern="std :: list|forward_list &lt;" inherits="stdContainer">
     <size>
       <function name="push_back" action="push"/>
-      <function name="emplace_back" action="push"/>
+      <function name="emplace_back" action="push" yields="item"/>
       <function name="emplace_after" action="push"/>
       <function name="pop_back" action="pop"/>
       <function name="push_front" action="push"/>
-      <function name="emplace_front" action="push"/>
+      <function name="emplace_front" action="push" yields="item"/>
       <function name="pop_front" action="pop"/>
       <function name="erase_after" action="erase"/>
       <function name="insert_after" action="insert"/>
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index 86819458c..3a7672159 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -72,6 +72,21 @@ static bool isElementAccessYield(const Library::Container::Yield& yield)
     return contains({Library::Container::Yield::ITEM, Library::Container::Yield::AT_INDEX}, yield);
 }
 
+static bool containerAppendsElement(const Library::Container* container, const Token* parent)
+{
+    if (Token::Match(parent, ". %name% (")) {
+        Library::Container::Action action = container->getAction(parent->strAt(1));
+        if (contains({Library::Container::Action::INSERT,
+                      Library::Container::Action::CHANGE,
+                      Library::Container::Action::CHANGE_INTERNAL,
+                      Library::Container::Action::PUSH,
+                      Library::Container::Action::RESIZE},
+                     action))
+            return true;
+    }
+    return false;
+}
+
 static bool containerYieldsElement(const Library::Container* container, const Token* parent)
 {
     if (Token::Match(parent, ". %name% (")) {
@@ -86,7 +101,7 @@ static const Token* getContainerIndex(const Library::Container* container, const
 {
     if (Token::Match(parent, ". %name% (")) {
         Library::Container::Yield yield = container->getYield(parent->strAt(1));
-        if (isElementAccessYield(yield) && !Token::simpleMatch(parent->tokAt(2), "( )"))
+        if (yield == Library::Container::Yield::AT_INDEX && !Token::simpleMatch(parent->tokAt(2), "( )"))
             return parent->tokAt(2)->astOperand2();
     }
     if (!container->arrayLike_indexOp && !container->stdStringLike)
@@ -133,7 +148,8 @@ void CheckStl::outOfBounds()
                     continue;
                 if (!value.errorSeverity() && !mSettings->severity.isEnabled(Severity::warning))
                     continue;
-                if (value.intvalue == 0 && (indexTok || containerYieldsElement(container, parent))) {
+                if (value.intvalue == 0 && (indexTok || (containerYieldsElement(container, parent) &&
+                                                         !containerAppendsElement(container, parent)))) {
                     std::string indexExpr;
                     if (indexTok && !indexTok->hasKnownValue())
                         indexExpr = indexTok->expressionString();
diff --git a/test/testautovariables.cpp b/test/testautovariables.cpp
index 5653de030..18f083b16 100644
--- a/test/testautovariables.cpp
+++ b/test/testautovariables.cpp
@@ -2565,6 +2565,13 @@ private:
               "    }\n"
               "};\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n"
+              "	std::queue<int> q;\n"
+              "	auto& h = q.emplace();\n"
+              "    h = 1;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void danglingLifetimeContainerView()