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Fixed #1732 (False positive: Variable not assigned a value (pointer to pointer))

This commit is contained in:
Robert Reif 2010-06-23 06:54:14 +02:00 committed by Daniel Marjamäki
parent fac9f66cc0
commit 74e48d4bb1
2 changed files with 83 additions and 66 deletions
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108
lib/checkother.cpp
View File

@ -422,7 +422,7 @@ static bool isOp(const Token *tok)
class Variables
{
public:
enum VariableType { standard, array, pointer, reference, pointerArray, referenceArray };
enum VariableType { standard, array, pointer, reference, pointerArray, referenceArray, pointerPointer };
/** Store information about variable usage */
class VariableUsage
@ -730,7 +730,7 @@ Variables::VariableUsage *Variables::find(unsigned int varid)
return 0;
}
static int doAssignment(Variables &variables, const Token *tok, bool pointer, bool post, bool paren)
static int doAssignment(Variables &variables, const Token *tok, bool dereference)
{
int next = 0;
@ -741,12 +741,12 @@ static int doAssignment(Variables &variables, const Token *tok, bool pointer, bo
if (var1)
{
Variables::VariableUsage *var2 = 0;
int start = 2;
int start = 1;
if (post)
// search for '='
while (tok->tokAt(start)->str() != "=")
start++;
if (paren)
start++;
if (Token::Match(tok->tokAt(start), "&| %var%") ||
@ -829,28 +829,13 @@ static int doAssignment(Variables &variables, const Token *tok, bool pointer, bo
varid2 = tok->tokAt(next)->varId();
var2 = variables.find(varid2);
if (var1->_type != Variables::reference && !addressOf)
{
if (var2)
if (var2) // local variable (alias or read it)
{
if (var1->_type == Variables::pointer)
{
if (!(var2->_type == Variables::array || var2->_type == Variables::pointer))
if (dereference)
variables.read(varid2);
}
else
{
if (var2->_type == Variables::pointer && tok->tokAt(next +1)->str() == "[")
variables.readAliases(varid2);
variables.read(varid2);
}
}
}
if (var2) // local variable
{
if (var1->_type == Variables::pointer && !pointer)
{
if (addressOf ||
var2->_type == Variables::array ||
@ -859,16 +844,22 @@ static int doAssignment(Variables &variables, const Token *tok, bool pointer, bo
variables.alias(varid1, varid2);
}
}
}
else if (var1->_type == Variables::reference)
{
variables.alias(varid1, varid2);
}
else
{
if (var2->_type == Variables::pointer && tok->tokAt(next + 1)->str() == "[")
variables.readAliases(varid2);
variables.read(varid2);
}
}
else // not a local variable (or an unsupported local variable)
{
if (var1->_type == Variables::pointer && !pointer)
if (var1->_type == Variables::pointer && !dereference)
{
// aliased variables in a larger scope are not supported
variables.clearAliases(varid1);
@ -1020,7 +1011,7 @@ void CheckOther::functionVariableUsage()
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(3), false, false, false);
offset = doAssignment(variables, tok->tokAt(3), false);
tok = tok->tokAt(3 + offset);
}
@ -1045,11 +1036,31 @@ void CheckOther::functionVariableUsage()
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(4), false, false, false);
offset = doAssignment(variables, tok->tokAt(4), false);
tok = tok->tokAt(4 + offset);
}
// pointer to pointer declaration with possible initialization
// int ** i; int ** j = 0;
else if (Token::Match(tok, "[;{}] %type% * * %var% ;|="))
{
if (tok->next()->str() != "return")
{
bool written = tok->tokAt(5)->str() == "=";
variables.addVar(tok->tokAt(4), Variables::pointerPointer, written);
int offset = 0;
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(4), false);
tok = tok->tokAt(4 + offset);
}
}
// pointer or reference of struct or union declaration with possible initialization
// struct s * i; struct s * j = 0;
else if (Token::Match(tok, "[;{}] const| struct|union %type% *|& %var% ;|="))
@ -1073,7 +1084,7 @@ void CheckOther::functionVariableUsage()
// check for assignment
if (written)
offset = doAssignment(variables, tok->tokAt(3), false, false, false);
offset = doAssignment(variables, tok->tokAt(3), false);
tok = tok->tokAt(3 + offset);
}
@ -1199,8 +1210,11 @@ void CheckOther::functionVariableUsage()
// array of pointer or reference of struct or union declaration with possible initialization
// struct S * p[10]; struct T * q[10] = { 0 };
else if (Token::Match(tok, "[;{}] struct|union %type% *|& %var% [ %any% ] ;|="))
else if (Token::Match(tok, "[;{}] const| struct|union %type% *|& %var% [ %any% ] ;|="))
{
if (tok->next()->str() == "const")
tok = tok->next();
variables.addVar(tok->tokAt(4),
tok->tokAt(3)->str() == "*" ? Variables::pointerArray : Variables::referenceArray,
tok->tokAt(8)->str() == "=");
@ -1212,43 +1226,24 @@ void CheckOther::functionVariableUsage()
tok = tok->tokAt(7);
}
// const array of pointer or reference of struct or union declaration with possible initialization
// const struct S * p[10]; const struct T * q[10] = { 0 };
else if (Token::Match(tok, "[;{}] const struct|union %type% *|& %var% [ %any% ] ;|="))
{
variables.addVar(tok->tokAt(5),
tok->tokAt(4)->str() == "*" ? Variables::pointerArray : Variables::referenceArray,
tok->tokAt(9)->str() == "=");
// check for reading array size from local variable
if (tok->tokAt(7)->varId() != 0)
variables.read(tok->tokAt(7)->varId());
tok = tok->tokAt(8);
}
else if (Token::Match(tok, "delete|return|throw %var%"))
variables.readAll(tok->next()->varId());
// assignment
else if (Token::Match(tok, "*| (| ++|--| %var% ++|--| )| ="))
{
bool pointer = false;
bool dereference = false;
bool pre = false;
bool post = false;
bool paren = false;
if (tok->str() == "*")
{
pointer = true;
dereference = true;
tok = tok->next();
}
if (tok->str() == "(")
{
paren = true;
tok = tok->next();
}
if (Token::Match(tok, "++|--"))
{
@ -1257,19 +1252,17 @@ void CheckOther::functionVariableUsage()
}
if (Token::Match(tok->next(), "++|--"))
{
post = true;
}
unsigned int varid1 = tok->varId();
const Token *start = tok;
tok = tok->tokAt(doAssignment(variables, tok, pointer, post, paren));
tok = tok->tokAt(doAssignment(variables, tok, dereference));
if (pre || post)
variables.use(varid1);
if (pointer)
if (dereference)
{
variables.writeAliases(varid1);
variables.read(varid1);
@ -1363,18 +1356,29 @@ void CheckOther::functionVariableUsage()
const Variables::VariableUsage &usage = it->second;
const std::string &varname = usage._name->str();
// variable has been marked as unused so ignore it
if (usage._name->isUnused())
continue;
// skip things that are only partially implemented to prevent false positives
if (usage._type == Variables::pointerPointer ||
usage._type == Variables::pointerArray ||
usage._type == Variables::referenceArray)
continue;
// variable has not been written, read, or modified
if (usage.unused() && !usage._modified)
unusedVariableError(usage._name, varname);
// variable has not been written but has been modified
else if (usage._modified & !usage._write)
unassignedVariableError(usage._name, varname);
// variable has been written but not read
else if (!usage._read && !usage._modified)
unreadVariableError(usage._name, varname);
// variable has been read but not written
else if (!usage._write)
unassignedVariableError(usage._name, varname);
}

25
test/testunusedvar.cpp
View File

@ -73,6 +73,7 @@ private:
TEST_CASE(localvaralias4); // ticket #1643
TEST_CASE(localvaralias5); // ticket #1647
TEST_CASE(localvaralias6); // ticket #1729
TEST_CASE(localvaralias7); // ticket #1732
TEST_CASE(localvarasm);
// Don't give false positives for variables in structs/unions
@ -766,37 +767,37 @@ private:
"{\n"
" int * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo()\n"
"{\n"
" const int * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo()\n"
"{\n"
" void * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo()\n"
"{\n"
" const void * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo()\n"
"{\n"
" struct A * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo()\n"
"{\n"
" const struct A * i[2];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:3]: (style) Unused variable: i\n", errout.str());
functionVariableUsage("void foo(int n)\n"
"{\n"
@ -1763,6 +1764,18 @@ private:
TODO_ASSERT_EQUALS("", errout.str());
}
void localvaralias7() // ticket 1732
{
functionVariableUsage("void foo()\n"
"{\n"
" char *c[10];\n"
" char **cp;\n"
" cp = c;\n"
" *cp = 0;\n"
"}");
ASSERT_EQUALS("", errout.str());
}
void localvarasm()
{
functionVariableUsage("void foo(int &b)\n"