From e88a0c00c1f0febc372115f6500aea34785a417a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Thu, 28 Mar 2019 12:49:52 +0100
Subject: [PATCH] Fixed #9039 (STL: array index out of bounds: str.begin() + 1)

---
 lib/checkstl.cpp | 12 ++++++++++++
 test/teststl.cpp | 10 ++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index 2a44904a7..8fe75b2e7 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -73,6 +73,18 @@ void CheckStl::outOfBounds()
                     outOfBoundsError(tok, &value, nullptr);
                     continue;
                 }
+                if (Token::Match(tok, "%name% . %name% (") && container->getYield(tok->strAt(2)) == Library::Container::Yield::START_ITERATOR) {
+                    const Token *parent = tok->tokAt(3)->astParent();
+                    const Token *other = nullptr;
+                    if (Token::simpleMatch(parent, "+") && parent->astOperand1() && parent->astOperand1()->hasKnownIntValue())
+                        other = parent->astOperand1();
+                    else if (Token::simpleMatch(parent, "+") && parent->astOperand2() && parent->astOperand2()->hasKnownIntValue())
+                        other = parent->astOperand2();
+                    if (other && other->getKnownIntValue() > value.intvalue) {
+                        outOfBoundsError(tok, &value, &other->values().back());
+                        continue;
+                    }
+                }
                 if (!container->arrayLike_indexOp && !container->stdStringLike)
                     continue;
                 if (value.intvalue == 0 && Token::Match(tok, "%name% [")) {
diff --git a/test/teststl.cpp b/test/teststl.cpp
index 087d3857c..1a54a88c4 100644
--- a/test/teststl.cpp
+++ b/test/teststl.cpp
@@ -274,6 +274,12 @@ private:
                     "  x[0];\n"
                     "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        checkNormal("void f() {\n"
+                    "  std::string s;\n"
+                    "  x = s.begin() + 1;\n"
+                    "}\n");
+        ASSERT_EQUALS("test.cpp:3:error:Out of bounds access in s because s is empty.\n", errout.str());
     }
 
     void outOfBoundsIndexExpression() {
@@ -1130,7 +1136,7 @@ private:
     void dereference() {
         check("void f()\n"
               "{\n"
-              "    std::vector<int> ints;\n"
+              "    std::vector<int> ints{1,2,3,4,5};\n"
               "    std::vector<int>::iterator iter;\n"
               "    iter = ints.begin() + 2;\n"
               "    ints.erase(iter);\n"
@@ -1202,7 +1208,7 @@ private:
     void dereference_auto() {
         check("void f()\n"
               "{\n"
-              "    std::vector<int> ints;\n"
+              "    std::vector<int> ints{1,2,3,4,5};\n"
               "    auto iter = ints.begin() + 2;\n"
               "    ints.erase(iter);\n"
               "    std::cout << (*iter) << std::endl;\n"