Fixed #4695: Infinite recursion inside isRecordTypeWithoutSideEffects()

lib/checkunusedvar.cpp

@@ -22,6 +22,7 @@
 #include "symboldatabase.h"
 #include <algorithm>
 #include <cctype>
+#include <utility>
 //---------------------------------------------------------------------------
 
 // Register this check class (by creating a static instance of it)
@@ -618,20 +619,6 @@ static const Token* doAssignment(Variables &variables, const Token *tok, bool de
     return tok;
 }
 
-static bool isRecordTypeWithoutSideEffects(const Type* type)
-{
-    // a type that has no side effects (no constructors and no members with constructors)
-    /** @todo false negative: check constructors for side effects */
-    if (type && type->classScope && type->classScope->numConstructors == 0 &&
-        (type->classScope->varlist.empty() || type->needInitialization == Type::True)) {
-        bool yes = true;
-        for (std::vector<Type::BaseInfo>::const_iterator i = type->derivedFrom.begin(); yes && i != type->derivedFrom.end(); ++i)
-            yes = isRecordTypeWithoutSideEffects(i->type);
-        return yes;
-    }
-    return false;
-}
-
 static bool isPartOfClassStructUnion(const Token* tok)
 {
     for (; tok; tok = tok->previous()) {
@@ -1254,3 +1241,30 @@ void CheckUnusedVar::unusedStructMemberError(const Token *tok, const std::string
 {
     reportError(tok, Severity::style, "unusedStructMember", "struct or union member '" + structname + "::" + varname + "' is never used.");
 }
+
+bool CheckUnusedVar::isRecordTypeWithoutSideEffects(const Type* type)
+{
+    // a type that has no side effects (no constructors and no members with constructors)
+    /** @todo false negative: check constructors for side effects */
+
+    std::pair<std::map<Type const *,bool>::iterator,bool> found=isRecordTypeWithoutSideEffectsMap.insert(
+                std::pair<const Type *,bool>(type,false)); //Initialize with side effects for possilbe recursions
+    bool & withoutSideEffects=found.first->second;
+    if (!found.second)
+        return withoutSideEffects;
+
+    if (type && type->classScope && type->classScope->numConstructors == 0 &&
+        (type->classScope->varlist.empty() || type->needInitialization == Type::True)) {
+        for (std::vector<Type::BaseInfo>::const_iterator i = type->derivedFrom.begin(); i != type->derivedFrom.end(); ++i) {
+            if (!isRecordTypeWithoutSideEffects(i->type)) {
+                withoutSideEffects=false;
+                return withoutSideEffects;
+            }
+        }
+        withoutSideEffects=true;
+        return withoutSideEffects;
+    }
+
+    withoutSideEffects=false;   // unknown types are assumed to have side effects
+    return withoutSideEffects;
+}

lib/checkunusedvar.h

@@ -22,10 +22,13 @@
 #define CheckUnusedVarH
 //---------------------------------------------------------------------------
 
+#include <map>
+
 #include "config.h"
 #include "check.h"
 #include "settings.h"
 
+class Type;
 class Token;
 class Scope;
 class Variables;
@@ -72,6 +75,8 @@ public:
     void checkStructMemberUsage();
 
 private:
+    bool isRecordTypeWithoutSideEffects(const Type* type);
+
     // Error messages..
     void unusedStructMemberError(const Token *tok, const std::string &structname, const std::string &varname);
     void unusedVariableError(const Token *tok, const std::string &varname);
@@ -104,6 +109,8 @@ private:
                "* unassigned variable\n"
                "* unused struct member\n";
     }
+
+    std::map<const Type *,bool> isRecordTypeWithoutSideEffectsMap;
 };
 /// @}
 //---------------------------------------------------------------------------

test/testunusedvar.cpp

@@ -153,6 +153,7 @@ private:
         TEST_CASE(localvarUnusedGoto);    // #4447, #4558 goto
 
         TEST_CASE(crash1);
+        TEST_CASE(crash2);
         TEST_CASE(usingNamespace);     // #4585
     }
 
@@ -3653,6 +3654,16 @@ private:
                               "SAL_WNODEPRECATED_DECLARATIONS_POP"); // #4033
     }
 
+    void crash2() {
+        functionVariableUsage("template<unsigned dim>\n"
+                              "struct Y: Y<dim-1> { };\n"
+                              "template<>\n"
+                              "struct Y<0> {};\n"
+                              "void f() {\n"
+                              "    Y y;\n"
+                              "}"); // #4695
+    }
+
     void usingNamespace() {
         functionVariableUsage("int foo() {\n"
                               "   using namespace ::com::sun::star::i18n;\n"