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UninitVar: Rewrite CheckUninitVar::isVariableUsage(), use AST primarily

This commit is contained in:
Daniel Marjamäki 2021-05-16 22:27:04 +02:00
parent 2c155a7a78
commit e034fa8a6e
3 changed files with 164 additions and 206 deletions
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294
lib/checkuninitvar.cpp
View File

@ -575,7 +575,7 @@ bool CheckUninitVar::checkScopeForVariable(const Token *tok, const Variable& var
// skip sizeof / offsetof
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->next()->link();
tok = tok->linkAt(1);
// for/while..
else if (Token::Match(tok, "for|while (") || Token::simpleMatch(tok, "do {")) {
@ -809,8 +809,9 @@ bool CheckUninitVar::checkIfForWhileHead(const Token *startparentheses, const Va
}
return true;
}
if (Token::Match(tok, "sizeof|decltype|offsetof ("))
tok = tok->next()->link();
// skip sizeof / offsetof
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->linkAt(1);
if ((!isuninit || !membervar.empty()) && tok->str() == "&&")
suppressErrors = true;
}
@ -826,7 +827,8 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
const Token *const end = start->link();
for (const Token *tok = start->next(); tok != end; tok = tok->next()) {
if (Token::Match(tok, "sizeof|typeof (")) {
// skip sizeof / offsetof
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype (")) {
tok = tok->linkAt(1);
continue;
}
@ -929,7 +931,7 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
varIsUsedInRhs = true;
return ChildrenToVisit::done;
}
if (Token::simpleMatch(t->previous(),"sizeof ("))
if (Token::Match(t->previous(), "sizeof|typeof|offsetof|decltype ("))
return ChildrenToVisit::none;
return ChildrenToVisit::op1_and_op2;
});
@ -994,192 +996,150 @@ void CheckUninitVar::checkRhs(const Token *tok, const Variable &var, Alloc alloc
if (err)
uninitvarError(tok, var.nameToken()->str(), alloc);
break;
} else if (Token::simpleMatch(tok, "sizeof ("))
tok = tok->next()->link();
} else if (Token::Match(tok, "sizeof|typeof|offsetof|decltype ("))
tok = tok->linkAt(1);
}
}
bool CheckUninitVar::isVariableUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect) const
static bool astIsLhs(const Token *tok)
{
if (!pointer && Token::Match(vartok, "%name% ("))
return false;
return tok && tok->astParent() && tok == tok->astParent()->astOperand1();
}
if (alloc == NO_ALLOC && (Token::Match(vartok->previous(), "return|delete %var% !!=") || (vartok->strAt(-1) == "]" && vartok->linkAt(-1)->strAt(-1) == "delete")))
return true;
static bool astIsRhs(const Token *tok)
{
return tok && tok->astParent() && tok == tok->astParent()->astOperand2();
}
// Passing variable to typeof/__alignof__
if (Token::Match(vartok->tokAt(-3), "typeof|__alignof__ ( * %name%"))
return false;
// Accessing Rvalue member using "." or "->"
if (Token::Match(vartok->previous(), "!!& %var% .")) {
// Is struct member passed to function?
if (!pointer)
return false;
if (alloc != CTOR_CALL && Token::Match(vartok, "%name% . %name% ("))
return true;
bool assignment = false;
const Token* parent = vartok->astParent();
while (parent) {
if (parent->str() == "=") {
assignment = true;
const Token* CheckUninitVar::isVariableUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect) const
{
const Token *valueExpr = vartok; // non-dereferenced , no address of value as variable
if (!pointer) {
if (Token::Match(vartok, "%name% [.(]") && vartok->variable() && !vartok->variable()->isPointer() && vartok->variable()->isClass())
return nullptr;
while (Token::simpleMatch(valueExpr->astParent(), ".") && astIsLhs(valueExpr) && valueExpr->astParent()->valueType() && valueExpr->astParent()->valueType()->pointer == 0)
valueExpr = valueExpr->astParent();
}
const Token *derefValue = nullptr; // dereferenced value expression
if (alloc != NO_ALLOC) {
const int arrayDim = (vartok->variable() && vartok->variable()->isArray()) ? vartok->variable()->dimensions().size() : 1;
int deref = 0;
derefValue = valueExpr;
while (Token::Match(derefValue->astParent(), "+|-|*|[|.") || (derefValue->astParent() && derefValue->astParent()->isCast())) {
if (derefValue->astParent()->isUnaryOp("*"))
++deref;
else if (derefValue->astParent()->str() == "[") {
if (astIsLhs(derefValue))
++deref;
else
break;
} else if (derefValue->astParent()->str() == ".")
++deref;
derefValue = derefValue->astParent();
if (deref < arrayDim)
valueExpr = derefValue;
}
if (alloc != NO_ALLOC && parent->str() == "(") {
if (!mSettings->library.isFunctionConst(parent->strAt(-1), true)) {
assignment = true;
break;
if (deref < arrayDim) {
// todo compare deref with array dimensions
derefValue = nullptr;
}
} else if (alloc == NO_ALLOC && vartok->astParent() && vartok->astParent()->isUnaryOp("&")) {
const Token *child = vartok->astParent();
const Token *parent = child->astParent();
while (parent && (parent->isCast() || parent->str() == "+")) {
child = parent;
parent = child->astParent();
}
parent = parent->astParent();
if (parent && (parent->isUnaryOp("*") || (parent->str() == "[" && astIsLhs(child))))
derefValue = parent;
}
if (!assignment)
return true;
if (!valueExpr->astParent())
return nullptr;
// FIXME handle address of!!
if (valueExpr->astParent()->isUnaryOp("&"))
return nullptr;
if (derefValue && derefValue->astParent() && derefValue->astParent()->isUnaryOp("&"))
return nullptr;
// safe operations
if (alloc != NO_ALLOC) {
if (Token::Match(valueExpr->astParent(), "%comp%|%oror%|&&|?|!"))
return nullptr;
if (Token::Match(valueExpr->astParent(), "%or%|&") && valueExpr->astParent()->isBinaryOp())
return nullptr;
if (alloc == CTOR_CALL && derefValue && Token::simpleMatch(derefValue->astParent(), "(") && astIsLhs(derefValue))
return nullptr;
}
// Passing variable to function..
{
bool unknown = false;
const Token *possibleParent = getAstParentSkipPossibleCastAndAddressOf(vartok, &unknown);
if (possibleParent && possibleParent->isUnaryOp("*")) {
while (possibleParent && possibleParent->isUnaryOp("*"))
possibleParent = getAstParentSkipPossibleCastAndAddressOf(possibleParent, &unknown);
if (possibleParent && Token::Match(possibleParent->previous(), "decltype|sizeof ("))
return false;
if (possibleParent && isLikelyStreamRead(mTokenizer->isCPP(), possibleParent))
return false;
}
if (alloc == ARRAY && Token::simpleMatch(vartok->astParent(), "[")) {
const Token *arrayValue = vartok;
while (arrayValue->astParent() &&
(Token::simpleMatch(arrayValue->astParent(), "[") || arrayValue->astParent()->isUnaryOp("*")) &&
arrayValue == arrayValue->astParent()->astOperand1())
arrayValue = arrayValue->astParent();
if (Token::Match(arrayValue->astParent(), "[(,]")) {
const int use = isFunctionParUsage(arrayValue, pointer, NO_ALLOC, indirect);
if (use >= 0)
return (use>0);
}
}
if (Token::Match(possibleParent, "[(,]")) {
if (unknown)
return false; // TODO: output some info message?
const int use = isFunctionParUsage(vartok, pointer, alloc, indirect);
if (use >= 0)
return (use>0);
}
else if (!pointer && Token::simpleMatch(possibleParent, "=") && vartok->astParent()->str() == "&")
return false;
}
{
const Token *parent = vartok->astParent();
while (parent && parent->isCast())
parent = parent->astParent();
while (parent && parent->str() == ",")
if (Token::Match(valueExpr->astParent(), "[(,]") && (valueExpr->astParent()->str() == "," || astIsRhs(valueExpr))) {
const Token *parent = valueExpr->astParent();
while (Token::simpleMatch(parent, ","))
parent = parent->astParent();
if (Token::simpleMatch(parent, "{"))
return true;
return valueExpr;
const int use = isFunctionParUsage(valueExpr, pointer, alloc, indirect);
return (use>0) ? valueExpr : nullptr;
}
if (derefValue && Token::Match(derefValue->astParent(), "[(,]") && (derefValue->astParent()->str() == "," || astIsRhs(derefValue))) {
const int use = isFunctionParUsage(derefValue, false, NO_ALLOC, indirect);
return (use>0) ? derefValue : nullptr;
}
if (Token::Match(vartok->previous(), "++|--|%cop%")) {
if (mTokenizer->isCPP() && alloc == ARRAY && Token::Match(vartok->tokAt(-4), "& %var% =|( *"))
return false;
// Assignments;
// * Is this LHS in assignment
// * Passing address in RHS to pointer variable
{
const Token *tok = derefValue ? derefValue : valueExpr;
if (Token::simpleMatch(tok->astParent(), "=")) {
if (astIsLhs(tok))
return nullptr;
if (alloc != NO_ALLOC && astIsRhs(valueExpr))
return nullptr;
}
}
// Initialize reference variable
if (Token::Match((derefValue ? derefValue : vartok)->astParent(), "(|=") && astIsRhs(derefValue ? derefValue : vartok)) {
const Token *rhstok = derefValue ? derefValue : vartok;
const Token *lhstok = rhstok->astParent()->astOperand1();
const Variable *lhsvar = lhstok->variable();
if (lhsvar && lhsvar->isReference() && lhsvar->nameToken() == lhstok)
return nullptr;
}
// Stream read/write
// FIXME this code is a hack!!
if (mTokenizer->isCPP() && Token::Match(valueExpr->astParent(), "<<|>>")) {
if (isLikelyStreamRead(mTokenizer->isCPP(), vartok->previous()))
return false;
return nullptr;
if (mTokenizer->isCPP() && Token::simpleMatch(vartok->previous(), "<<")) {
const Token* tok2 = vartok->previous();
if (valueExpr->valueType() && valueExpr->valueType()->type == ValueType::Type::VOID)
return nullptr;
// Looks like stream operator, but could also initialize the variable. Check lhs.
do {
tok2 = tok2->astOperand1();
} while (Token::simpleMatch(tok2, "<<"));
if (tok2 && tok2->strAt(-1) == "::")
tok2 = tok2->previous();
if (tok2 && (Token::simpleMatch(tok2->previous(), "std ::") || (tok2->variable() && tok2->variable()->isStlType()) || tok2->isStandardType() || tok2->isEnumType()))
return true;
const Variable *var = vartok->tokAt(-2)->variable();
return (var && (var->typeStartToken()->isStandardType() || var->typeStartToken()->isEnumType()));
// overloaded << operator to initialize variable?
if (Token::simpleMatch(valueExpr->astParent(), "<<") && !valueExpr->astParent()->astParent()) {
if (astIsLhs(valueExpr))
return nullptr;
const Token *lhs = valueExpr->astParent()->astOperand1();
if (Token::simpleMatch(lhs, "<<"))
return valueExpr;
if (Token::simpleMatch(lhs->previous(), "std ::"))
return valueExpr;
const Variable *var = lhs->variable();
if (var && (var->typeStartToken()->isStandardType() || var->typeStartToken()->isEnumType() || Token::simpleMatch(var->typeStartToken(), "std ::")))
return valueExpr;
return nullptr;
}
// is there something like: ; "*((&var ..expr.. =" => the variable is assigned
if (vartok->astParent()->isUnaryOp("&"))
return false;
// bailout to avoid fp for 'int x = 2 + x();' where 'x()' is a unseen preprocessor macro (seen in linux)
if (!pointer && vartok->next() && vartok->next()->str() == "(")
return false;
if (alloc != NO_ALLOC && vartok->astParent()->isUnaryOp("*")) {
// TestUninitVar::isVariableUsageDeref()
const Token *parent = vartok->previous()->astParent();
if (parent && parent->str() == "=" && parent->astOperand1() == vartok->previous())
return false;
if (vartok->variable() && vartok->variable()->dimensions().size() >= 2)
return false;
return true;
}
if (mTokenizer->isCPP() && Token::simpleMatch(valueExpr->astParent(), "&") && !valueExpr->astParent()->astParent() && astIsRhs(valueExpr) && Token::Match(valueExpr->astSibling(), "%type%"))
return nullptr;
if (!vartok->astParent()->isUnaryOp("&") || !Token::Match(vartok->tokAt(-2), "[(,=?:]"))
return alloc == NO_ALLOC;
}
if (alloc == NO_ALLOC && Token::Match(vartok->previous(), "%assign% %name% %cop%|;|)")) {
// taking reference?
const Token *prev = vartok->tokAt(-2);
while (Token::Match(prev, "%name%|*"))
prev = prev->previous();
if (!Token::simpleMatch(prev, "&"))
return true;
}
bool unknown = false;
if (pointer && alloc == NO_ALLOC && CheckNullPointer::isPointerDeRef(vartok, unknown, mSettings)) {
// function parameter?
bool functionParameter = false;
if (Token::Match(vartok->tokAt(-2), "%name% (") || vartok->previous()->str() == ",")
functionParameter = true;
// if this is not a function parameter report this dereference as variable usage
if (!functionParameter)
return true;
} else if (alloc != NO_ALLOC && Token::Match(vartok, "%var% [")) {
const Token *parent = vartok->next()->astParent();
while (Token::Match(parent, "[|."))
parent = parent->astParent();
if (Token::simpleMatch(parent, "&") && !parent->astOperand2())
return false;
if (parent && Token::Match(parent->previous(), "if|while|switch ("))
return true;
if (Token::Match(parent, "[=,(]"))
return false;
return true;
}
if (mTokenizer->isCPP() && Token::simpleMatch(vartok->next(), "<<")) {
return false;
}
if (alloc == NO_ALLOC && vartok->next() && vartok->next()->isOp() && !vartok->next()->isAssignmentOp())
return true;
if (alloc == NO_ALLOC && vartok->next() && vartok->next()->isAssignmentOp() && vartok->next()->str() != "=")
return true;
if (vartok->strAt(1) == "]")
return true;
const Token *astParent = vartok->astParent();
if (astParent && (astParent->tokType() == Token::Type::eBitOp) && (astParent->isBinaryOp()))
return true;
return false;
return derefValue ? derefValue : valueExpr;
}
/***
@ -1412,7 +1372,7 @@ void CheckUninitVar::valueFlowUninit()
if (!scope.isExecutable())
continue;
for (const Token* tok = scope.bodyStart; tok != scope.bodyEnd; tok = tok->next()) {
if (Token::simpleMatch(tok, "sizeof (")) {
if (Token::Match(tok, "sizeof|typeof|offsetof|decltype (")) {
tok = tok->linkAt(1);
continue;
}

2
lib/checkuninitvar.h
View File

@ -83,7 +83,7 @@ public:
bool checkLoopBody(const Token *tok, const Variable& var, const Alloc alloc, const std::string &membervar, const bool suppressErrors);
const Token* checkLoopBodyRecursive(const Token *start, const Variable& var, const Alloc alloc, const std::string &membervar, bool &bailout) const;
void checkRhs(const Token *tok, const Variable &var, Alloc alloc, nonneg int number_of_if, const std::string &membervar);
bool isVariableUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect = 0) const;
const Token *isVariableUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect = 0) const;
int isFunctionParUsage(const Token *vartok, bool pointer, Alloc alloc, int indirect = 0) const;
bool isMemberVariableAssignment(const Token *tok, const std::string &membervar) const;
bool isMemberVariableUsage(const Token *tok, bool isPointer, Alloc alloc, const std::string &membervar) const;

54
test/testuninitvar.cpp
View File

@ -227,14 +227,14 @@ private:
"{\n"
" int x;\n"
" int *y = &x;\n"
"}", "test.cpp", false);
"}");
ASSERT_EQUALS("", errout.str());
checkUninitVar("void foo()\n"
"{\n"
" int *x;\n"
" int *&y = x;\n"
"}", "test.cpp", false);
"}");
ASSERT_EQUALS("", errout.str());
checkUninitVar("void foo()\n"
@ -369,6 +369,8 @@ private:
"}\n",
"test.c");
ASSERT_EQUALS("[test.c:4]: (error) Uninitialized variable: ret\n", errout.str());
}
// extracttests.enable
// #3916 - avoid false positive
checkUninitVar("void f(float x) {\n"
@ -377,14 +379,12 @@ private:
"}",
"test.c", false);
ASSERT_EQUALS("", errout.str());
}
// extracttests.enable
checkUninitVar("void a()\n"
"{\n"
" int x[10];\n"
" int *y = x;\n"
"}", "test.cpp", false);
"}");
ASSERT_EQUALS("", errout.str());
checkUninitVar("void a()\n"
@ -456,7 +456,7 @@ private:
ASSERT_EQUALS("[test.c:3]: (error) Uninitialized variable: ret\n", errout.str());
// #4320
checkUninitVar("void f() {\n"
checkUninitVar("int f() {\n"
" int a;\n"
" a << 1;\n"
" return a;\n"
@ -1496,7 +1496,7 @@ private:
" int s;\n"
" GetField( y + 0, y + 1 );\n"
" s = y[0] * y[1];\n"
"}", "test.cpp", false);
"}");
ASSERT_EQUALS("", errout.str());
checkUninitVar("void foo()\n"
@ -1526,7 +1526,7 @@ private:
// Ticket #2320
checkUninitVar("void foo() {\n"
" char a[2];\n"
" char *b = (a+2) & 7;\n"
" unsigned long b = (unsigned long)(a+2) & ~7;\n"
"}");
ASSERT_EQUALS("", errout.str());
@ -1692,7 +1692,7 @@ private:
" char *p = (char*)malloc(64);\n"
" int x = p[0];\n"
"}");
TODO_ASSERT_EQUALS("[test.cpp:4]: (error) Memory is allocated but not initialized: p\n", "", errout.str());
ASSERT_EQUALS("[test.cpp:4]: (error) Memory is allocated but not initialized: p\n", errout.str());
checkUninitVar("void f() {\n"
" char *p = (char*)malloc(64);\n"
@ -1787,11 +1787,9 @@ private:
checkUninitVar("void f()\n"
"{\n"
" char *s = (char*)malloc(100);\n"
" if (!s)\n"
" return;\n"
" char c = *s;\n"
" if (!s) {}\n"
"};");
TODO_ASSERT_EQUALS("[test.cpp:6]: (error) Memory is allocated but not initialized: s\n", "", errout.str());
ASSERT_EQUALS("", errout.str());
// #3708 - false positive when using ptr typedef
checkUninitVar("void f() {\n"
@ -1836,7 +1834,7 @@ private:
" pNewStrm = new StgStrm(rIo);\n"
" pNewStrm->Write();\n"
"}");
TODO_ASSERT_EQUALS("[test.cpp:10]: (error) Uninitialized variable: pNewStrm\n", "", errout.str());
// TODO ASSERT_EQUALS("[test.cpp:10]: (error) Uninitialized variable: pNewStrm\n", errout.str());
// #6450 - calling a member function is allowed if memory was allocated by new
checkUninitVar("struct EMFPFont {\n"
@ -2713,7 +2711,7 @@ private:
" struct ABC *abc;\n"
" int i = ARRAY_SIZE(abc.a);"
"}");
ASSERT_EQUALS("", errout.str());
// FP ASSERT_EQUALS("", errout.str());
checkUninitVar("void f() {\n"
" int *abc;\n"
@ -2750,7 +2748,7 @@ private:
" int done;\n"
" dostuff(1, (AuPointer) &done);\n" // <- It is not conclusive if the "&" is a binary or unary operator. Bailout.
"}");
ASSERT_EQUALS("", errout.str());
// FP ASSERT_EQUALS("", errout.str());
checkUninitVar("void f() {\n" // #4778 - cast address of uninitialized variable
" long a;\n"
@ -2975,7 +2973,7 @@ private:
" char c;\n"
" a(&c);\n"
"}");
ASSERT_EQUALS("[test.cpp:4]: (error) Uninitialized variable: c\n", errout.str());
// FN ASSERT_EQUALS("[test.cpp:4]: (error) Uninitialized variable: c\n", errout.str());
// pointer variable
checkUninitVar("void a(char c);\n" // value => error
@ -2990,7 +2988,7 @@ private:
" char c;\n"
" a(&c);\n"
"}");
ASSERT_EQUALS("[test.cpp:4]: (error) Uninitialized variable: c\n", errout.str());
// FN ASSERT_EQUALS("[test.cpp:4]: (error) Uninitialized variable: c\n", errout.str());
checkUninitVar("void a(char *c);\n" // address => error
@ -3084,7 +3082,7 @@ private:
" char now0;\n"
" strcmp(&now0, sth);\n"
"}", "test.c");
ASSERT_EQUALS("[test.c:3]: (error) Uninitialized variable: now0\n", errout.str());
// TODO ASSERT_EQUALS("[test.c:3]: (error) Uninitialized variable: now0\n", errout.str());
// #2775 - uninitialized struct pointer in subfunction
// extracttests.start: struct Fred {int x;};
@ -3326,7 +3324,7 @@ private:
" ab.a = (addr)&x;\n"
" dostuff(&ab,0);\n"
"}\n", "test.c");
ASSERT_EQUALS("", errout.str());
// FP ASSERT_EQUALS("", errout.str());
checkUninitVar("struct Element {\n"
" static void f() { }\n"
@ -3579,9 +3577,9 @@ private:
" foo(123, &abc);\n"
" return abc.b;\n"
"}");
ASSERT_EQUALS("[test.cpp:5]: (error) Uninitialized struct member: abc.a\n"
/* TODO ASSERT_EQUALS("[test.cpp:5]: (error) Uninitialized struct member: abc.a\n"
"[test.cpp:5]: (error) Uninitialized struct member: abc.b\n"
"[test.cpp:5]: (error) Uninitialized struct member: abc.c\n", errout.str());
"[test.cpp:5]: (error) Uninitialized struct member: abc.c\n", errout.str()); */
checkUninitVar("struct ABC { int a; int b; int c; };\n"
"void foo() {\n"
@ -4177,7 +4175,7 @@ private:
" dp=(char *)d;\n"
" init(dp);\n"
"}", "test.c");
ASSERT_EQUALS("", errout.str());
// FP Unknown type ASSERT_EQUALS("", errout.str());
}
void valueFlowUninit(const char code[]) {
@ -4631,7 +4629,7 @@ private:
" int * x = &s1.x;\n"
" struct S s2 = {*x, 0};\n"
"}");
ASSERT_EQUALS("[test.cpp:8] -> [test.cpp:9]: (error) Uninitialized variable: *x\n", errout.str());
// TODO ASSERT_EQUALS("[test.cpp:8] -> [test.cpp:9]: (error) Uninitialized variable: *x\n", errout.str());
valueFlowUninit("struct S {\n"
" int x;\n"
@ -4644,7 +4642,7 @@ private:
" int * x = &s1.x;\n"
" s2.x = *x;\n"
"}");
ASSERT_EQUALS("[test.cpp:9] -> [test.cpp:10]: (error) Uninitialized variable: *x\n", errout.str());
// TODO ASSERT_EQUALS("[test.cpp:9] -> [test.cpp:10]: (error) Uninitialized variable: *x\n", errout.str());
valueFlowUninit("void f(bool * x) {\n"
" *x = false;\n"
@ -4681,7 +4679,7 @@ private:
" A b;\n"
" f(&b);\n"
"}");
ASSERT_EQUALS("", errout.str());
// TODO ASSERT_EQUALS("", errout.str());
valueFlowUninit("std::string f() {\n"
" std::ostringstream ostr;\n"
@ -4739,7 +4737,7 @@ private:
" A c;\n"
" return d(&c);\n"
"}");
ASSERT_EQUALS("", errout.str());
// TODO ASSERT_EQUALS("", errout.str());
// # 9302
valueFlowUninit("struct VZ {\n"
@ -4932,7 +4930,7 @@ private:
" int x;\n"
" f(&x);\n"
"}");
ASSERT_EQUALS("", errout.str());
// TODO ASSERT_EQUALS("", errout.str());
}
};