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Fixed #1639 (False positive: unused variable value (pointer aliasing))

This commit is contained in:
Robert Reif 2010-05-04 17:26:09 +02:00 committed by Daniel Marjamäki
parent 707d27f3d8
commit eb276346c5
2 changed files with 54 additions and 0 deletions
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41
lib/checkother.cpp
View File

@ -503,6 +503,8 @@ public:
{
_varUsage.erase(varid);
}
void eraseAliases(unsigned int varid);
void eraseAll(unsigned int varid);
private:
VariableMap _varUsage;
@ -551,6 +553,25 @@ void Variables::alias(unsigned int varid1, unsigned int varid2)
var2->_read = true;
}
void Variables::eraseAliases(unsigned int varid)
{
VariableUsage *usage = find(varid);
if (usage)
{
std::set<unsigned int>::iterator aliases;
for (aliases = usage->_aliases.begin(); aliases != usage->_aliases.end(); ++aliases)
erase(*aliases);
}
}
void Variables::eraseAll(unsigned int varid)
{
eraseAliases(varid);
erase(varid);
}
void Variables::addVar(const Token *name,
VariableType type,
bool write_)
@ -832,6 +853,26 @@ static int doAssignment(Variables &variables, const Token *tok, bool pointer)
}
}
// check for alias to struct member
// char c[10]; a.b = c;
else if (Token::Match(tok->tokAt(-2), "%var% ."))
{
if (Token::Match(tok->tokAt(2), "%var%"))
{
unsigned int varid2 = tok->tokAt(2)->varId();
Variables::VariableUsage *var2 = variables.find(varid2);
// struct member aliased to local variable
if (var2 && (var2->_type == Variables::array ||
var2->_type == Variables::pointer))
{
// erase aliased variable and all variables that alias it
// to prevent false positives
variables.eraseAll(varid2);
}
}
}
return next;
}

13
test/testunusedvar.cpp
View File

@ -78,6 +78,7 @@ private:
TEST_CASE(localvar13); // ticket #1640
TEST_CASE(localvaralias1);
TEST_CASE(localvaralias2); // ticket #1637
TEST_CASE(localvaralias3); // ticket #1639
TEST_CASE(localvarasm);
// Don't give false positives for variables in structs/unions
@ -1408,6 +1409,18 @@ private:
ASSERT_EQUALS(std::string(""), errout.str());
}
void localvaralias3() // ticket 1639
{
functionVariableUsage("void foo()\n"
"{\n"
" BROWSEINFO info;\n"
" char szDisplayName[MAX_PATH];\n"
" info.pszDisplayName = szDisplayName;\n"
" SHBrowseForFolder(&info);\n"
"}\n");
ASSERT_EQUALS(std::string(""), errout.str());
}
void localvarasm()
{
functionVariableUsage("void foo(int &b)\n"