From d3087602a1e497bbd10f90defe0f859c5e313d69 Mon Sep 17 00:00:00 2001
From: PKEuS <philipp.kloke@web.de>
Date: Sat, 16 Feb 2013 02:20:18 -0800
Subject: [PATCH] Fixed false positive "function can be const" if a non-const
 expression is inside []-brackets (#4406)

---
 lib/checkclass.cpp |  5 ++++-
 test/testclass.cpp | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index ed2cf6df5..b512e0e0d 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -1546,6 +1546,7 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, bool&
             if (tok1->str() == "this" && tok1->previous()->isAssignmentOp())
                 return(false);
 
+            const Token* jumpBackToken = 0;
             const Token *lastVarTok = tok1;
             const Token *end = tok1;
             for (;;) {
@@ -1560,6 +1561,8 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, bool&
                         if (var && Token::simpleMatch(var->typeStartToken(), "std :: map")) // operator[] changes a map
                             return(false);
                     }
+                    if (!jumpBackToken)
+                        jumpBackToken = end->next(); // Check inside the [] brackets
                     end = end->linkAt(1);
                 } else if (end->strAt(1) == ")")
                     end = end->next();
@@ -1600,7 +1603,7 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, bool&
             if (start->strAt(-1) == "delete")
                 return(false);
 
-            tok1 = end;
+            tok1 = jumpBackToken?jumpBackToken:end; // Jump back to first [ to check inside, or jump to end of expression
         }
 
         // streaming: <<
diff --git a/test/testclass.cpp b/test/testclass.cpp
index 68403862e..3231a470b 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -163,6 +163,7 @@ private:
         TEST_CASE(constIfCfg);  // ticket #1881 - fp when there are #if
         TEST_CASE(constFriend); // ticket #1921 - fp for friend function
         TEST_CASE(constUnion);  // ticket #2111 - fp when there is a union
+        TEST_CASE(constArrayOperator); // #4406
 
         TEST_CASE(initializerListOrder);
         TEST_CASE(initializerListUsage);
@@ -5336,6 +5337,23 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void constArrayOperator() {
+        checkConst("struct foo {\n"
+                   "    int x;\n"
+                   "    int y[5][724];\n"
+                   "    T a() {\n"
+                   "        return y[x++][6];\n"
+                   "    }\n"
+                   "    T b() {\n"
+                   "        return y[1][++x];\n"
+                   "    }\n"
+                   "    T c() {\n"
+                   "        return y[1][6];\n"
+                   "    }\n"
+                   "};");
+        ASSERT_EQUALS("[test.cpp:10]: (style, inconclusive) Technically the member function 'foo::c' can be const.\n", errout.str());
+    }
+
     void checkInitializerListOrder(const char code[]) {
         // Clear the error log
         errout.str("");