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Refactorized check for assigning function parameters: 

- Fixed false negative: Check is also valid for all non-references, not only for pointers.
- Fixed false negative: Usage before assignment doesn't require bailout
- Fixed false positive #4598 caused by inadequate usage of CheckUninitVar::isVariableUsage
- Made several member functions static
This commit is contained in:
PKEuS 2013-02-18 08:52:49 -08:00
parent 1c584208b4
commit 33cf561d85
3 changed files with 62 additions and 14 deletions
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26
lib/checkautovariables.cpp
View File

@ -36,6 +36,13 @@ namespace {
}
bool CheckAutoVariables::isPtrArg(const Token *tok)
{
const Variable *var = tok->variable();
return(var && var->isArgument() && var->isPointer());
}
bool CheckAutoVariables::isRefPtrArg(const Token *tok)
{
const Variable *var = tok->variable();
@ -43,11 +50,11 @@ bool CheckAutoVariables::isRefPtrArg(const Token *tok)
return(var && var->isArgument() && var->isReference() && var->isPointer());
}
bool CheckAutoVariables::isPtrArg(const Token *tok)
bool CheckAutoVariables::isNonReferenceArg(const Token *tok)
{
const Variable *var = tok->variable();
return(var && var->isArgument() && var->isPointer());
return(var && var->isArgument() && !var->isReference() && (var->isPointer() || var->typeStartToken()->isStandardType() || var->type()));
}
bool CheckAutoVariables::isAutoVar(const Token *tok)
@ -80,10 +87,14 @@ static bool checkRvalueExpression(const Variable* var, const Token* next)
return((next->str() != "." || (!var->isPointer() && (!var->isClass() || var->type()))) && next->strAt(2) != ".");
}
static bool pointerIsDereferencedInScope(const Variable *var, const Scope *scope, const bool cpp)
static bool variableIsUsedInScope(const Token* start, unsigned int varId, const Scope *scope)
{
for (const Token *tok = scope->classStart; tok && tok != scope->classEnd; tok = tok->next()) {
if (tok->varId() == var->varId() && CheckUninitVar::isVariableUsage(tok, true, cpp))
for (const Token *tok = start; tok != scope->classEnd; tok = tok->next()) {
if (tok->varId() == varId)
return true;
if (tok->scope()->type == Scope::eFor || tok->scope()->type == Scope::eDo || tok->scope()->type == Scope::eWhile) // In case of loops, better checking would be necessary
return true;
if (Token::simpleMatch(tok, "asm ("))
return true;
}
return false;
@ -110,9 +121,8 @@ void CheckAutoVariables::autoVariables()
errorAutoVariableAssignment(tok->next(), false);
} else if (reportWarnings &&
Token::Match(tok, "[;{}] %var% =") &&
isPtrArg(tok->next()) &&
Token::Match(tok->next()->variable()->typeStartToken(), "struct| %type% * %var% [,)]") &&
!pointerIsDereferencedInScope(tok->next()->variable(), scope, _tokenizer->isCPP())) {
isNonReferenceArg(tok->next()) &&
!variableIsUsedInScope(Token::findsimplematch(tok->tokAt(2), ";"), tok->next()->varId(), scope)) {
errorUselessAssignmentPtrArg(tok->next());
} else if (Token::Match(tok, "[;{}] %var% . %var% = & %var%")) {
// TODO: check if the parameter is only changed temporarily (#2969)

9
lib/checkautovariables.h
View File

@ -63,10 +63,11 @@ public:
void returnReference();
private:
bool isRefPtrArg(const Token *tok);
bool isPtrArg(const Token *tok);
bool isAutoVar(const Token *tok);
bool isAutoVarArray(const Token *tok);
static bool isPtrArg(const Token *tok);
static bool isRefPtrArg(const Token *tok);
static bool isNonReferenceArg(const Token *tok);
static bool isAutoVar(const Token *tok);
static bool isAutoVarArray(const Token *tok);
/**
* Returning a temporary object?

41
test/testautovariables.cpp
View File

@ -112,7 +112,7 @@ private:
" int num = 2;\n"
" res = #\n"
"}");
ASSERT_EQUALS("", errout.str());
ASSERT_EQUALS("[test.cpp:4]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("void func1(int **res)\n"
"{\n"
@ -141,7 +141,7 @@ private:
" int num = 2;\n"
" res = #\n"
"}");
ASSERT_EQUALS("", errout.str());
ASSERT_EQUALS("[test.cpp:7]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("class Fred {\n"
" void func1(int **res);\n"
@ -247,6 +247,11 @@ private:
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("void foo(int b) {\n"
" b = foo(b);\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("void foo(char* p) {\n"
" if (!p) p = buf;\n"
" *p = 0;\n"
@ -258,6 +263,38 @@ private:
" do_something(p);\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(char* p) {\n"
" while (!p) p = buf;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(char* p) {\n"
" p = 0;\n"
" asm(\"somecmd\");\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(Foo* p) {\n"
" p = 0;\n"
"}");
ASSERT_EQUALS("[test.cpp:2]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("class Foo {};\n"
"void foo(Foo p) {\n"
" p = 0;\n"
"}");
ASSERT_EQUALS("[test.cpp:3]: (warning) Assignment of function parameter has no effect outside the function.\n", errout.str());
check("void foo(Foo p) {\n"
" p = 0;\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void foo(int& p) {\n"
" p = 0;\n"
"}");
ASSERT_EQUALS("", errout.str());
}
void testautovar_array1() {