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Improved isVariableChangedByFunctionCall, better logic when parameter might be passed by reference

This commit is contained in:
Daniel Marjamäki 2019-02-28 17:02:46 +01:00
parent 7ccf4b9a0d
commit 4f5a426fe5
3 changed files with 10 additions and 4 deletions
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10
lib/astutils.cpp
View File

@ -811,6 +811,8 @@ bool isVariableChangedByFunctionCall(const Token *tok, const Settings *settings,
if (!tok)
return false;
const Token * const tok1 = tok;
// address of variable
const bool addressOf = tok->astParent() && tok->astParent()->isUnaryOp("&");
@ -844,10 +846,13 @@ bool isVariableChangedByFunctionCall(const Token *tok, const Settings *settings,
tok = tok->link();
else if (Token::Match(tok->previous(), "%name% ("))
break;
else if (Token::simpleMatch(tok->previous(), "> (") && tok->previous()->link())
break;
tok = tok->previous();
}
if (!tok || tok->str() != "(")
return false;
const bool possiblyPassedByReference = (tok->next() == tok1 || Token::Match(tok1->previous(), ", %name% [,)]"));
tok = tok->previous();
if (tok && tok->link() && tok->str() == ">")
tok = tok->link()->previous();
@ -879,12 +884,13 @@ bool isVariableChangedByFunctionCall(const Token *tok, const Settings *settings,
// => it is assumed that parameter is an in parameter (TODO: this is a bad heuristic)
if (!addressOf && settings && settings->library.isnullargbad(tok, 1+argnr))
return false;
// addressOf => inconclusive
if (!addressOf) {
// possible pass-by-reference => inconclusive
if (possiblyPassedByReference) {
if (inconclusive != nullptr)
*inconclusive = true;
return false;
}
// Safe guess: Assume that parameter is changed by function call
return true;
}

2
test/testastutils.cpp
View File

@ -135,7 +135,7 @@ private:
"}";
inconclusive = false;
ASSERT_EQUALS(false, isVariableChangedByFunctionCall(code, "x ) ;", &inconclusive));
// FIXME : ASSERT_EQUALS(true, inconclusive);
ASSERT_EQUALS(true, inconclusive);
}
bool nextAfterAstRightmostLeaf(const char code[], const char parentPattern[], const char rightPattern[]) {

2
test/testnullpointer.cpp
View File

@ -2536,7 +2536,7 @@ private:
ASSERT_EQUALS("", errout.str());
check("void f(int *p = 0) {\n"
" printf(\"%d\", p);\n"
" printf(\"%p\", p);\n"
" *p = 0;\n"
"}", true);
ASSERT_EQUALS("[test.cpp:3]: (warning, inconclusive) Possible null pointer dereference if the default parameter value is used: p\n", errout.str());