walkero
/
cppcheck
1
0
Fork 0
Code Issues Pull Requests Projects Releases 1 Wiki Activity

checkunusedvar: handle array element change using pointer arithmetic (#3000)

This commit is contained in:
miltolstoy 2021-01-01 09:06:20 +02:00 committed by GitHub
parent 8dc8aa0459
commit ee8d5b972a
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 117 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
lib/astutils.cpp
View File

@ -1681,6 +1681,23 @@ bool isVariableChanged(const Token *tok, int indirect, const Settings *settings,
return true;
return false;
}
if (indirect > 0)
{
// check for `*(ptr + 1) = new_value` case
parent = tok2->astParent();
while (parent && parent->isArithmeticalOp() && parent->isBinaryOp()) {
parent = parent->astParent();
}
if (Token::simpleMatch(parent, "*"))
{
if (parent->astParent() && parent->astParent()->isAssignmentOp() &&
(parent->astParent()->astOperand1() == parent)) {
return true;
}
}
}
return false;
}

3
lib/checkunusedvar.cpp
View File

@ -1620,9 +1620,6 @@ bool CheckUnusedVar::isFunctionWithoutSideEffects(const Function& func, const To
}
// check if global variable is changed
if (bodyVariable->isGlobal() || (pointersToGlobals.find(bodyVariable) != pointersToGlobals.end())) {
if (bodyVariable->isPointer() || bodyVariable->isArray()) {
return false; // TODO: Update astutils.cpp:1544 isVariableChanged() and remove this. Unhandled case: `*(global_arr + 1) = new_val`
}
const int depth = 20;
if (isVariableChanged(bodyToken, depth, mSettings, mTokenizer->isCPP())) {
return false;

104
test/testunusedvar.cpp
View File

@ -748,6 +748,23 @@ private:
"}");
ASSERT_EQUALS("", errout.str());
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
" *(x) = 2;\n"
" return 1;\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("", errout.str());
// pointer arithmetic on global array
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
@ -764,6 +781,87 @@ private:
"}");
ASSERT_EQUALS("", errout.str());
functionVariableUsage(
"int x[][] = {{0, 1}, {2, 3}};\n"
"int func() {\n"
" *((x + 1) + 1) = 4;\n"
" return 1;\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("", errout.str());
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
" int local = *(x + 1);\n"
" (void) local;\n"
" return 1;\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", errout.str());
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
" int* local = x + 2;\n"
" (void) local;\n"
" return 1;\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", errout.str());
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
" int* local = x + 2;\n"
" return *local;\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("", errout.str());
functionVariableUsage(
"int x[] = {0, 1, 3};\n"
"int func() {\n"
" return *(x + 1);\n"
"}\n"
"class C {\n"
"public:\n"
" C() : x(func()) {}\n"
" int x;\n"
"};\n"
"void f() {\n"
" C c;\n"
"}");
ASSERT_EQUALS("", errout.str());
// changing local variable
functionVariableUsage(
"int func() {\n"
@ -1064,8 +1162,7 @@ private:
"void f() {\n"
" C c;\n"
"}");
// TODO: see TODO for global vars under CheckUnusedVar::isFunctionWithoutSideEffects()
TODO_ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", "", errout.str());
ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", errout.str());
// global struct variable modification
functionVariableUsage(
@ -1135,8 +1232,7 @@ private:
"void f() {\n"
" C c;\n"
"}");
// TODO: see TODO for global vars under CheckUnusedVar::isFunctionWithoutSideEffects()
TODO_ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", "", errout.str());
ASSERT_EQUALS("[test.cpp:13]: (style) Unused variable: c\n", errout.str());
}
// #5355 - False positive: Variable is not assigned a value.