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Fix #15005: FP uninitdata with compound assignment or increment #8822

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Fix #15005: FP uninitdata with compound assignment or increment #8822

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4eade06
impl and tests
aadanen Sep 1, 2026
4d9473b
handle ++/-- and avoid ctu stuff
aadanen Sep 2, 2026
2745f45
made comment more concise
aadanen Sep 8, 2026
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15 changes: 14 additions & 1 deletion lib/checkuninitvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -834,7 +834,7 @@ bool CheckUninitVarImpl::checkScopeForVariable(const Token *tok, const Variable&
}
}
}
if (Token::simpleMatch(parent->astParent(), "=") && astIsLHS(parent)) {
if (parent->astParent() && parent->astParent()->isAssignmentOp() && astIsLHS(parent)) {
const Token *eq = parent->astParent();
if (const Token *errorToken = checkExpr(eq->astOperand2(), var, *alloc, number_of_if==0)) {
if (!suppressErrors)
Expand Down Expand Up @@ -1295,6 +1295,19 @@ const Token* CheckUninitVarImpl::isVariableUsage(const Token *vartok, const Libr
}
if (alloc != NO_ALLOC && astIsRhs(valueExpr))
return nullptr;
} else if (tok->astParent() && (tok->astParent()->isAssignmentOp() || tok->astParent()->isIncDecOp())) {
// NO_ALLOC -> no matter what we read the uninitialized memory.
// pointer/array -> safe, as long as we don't dereference
bool isPtr = pointer;
bool isArr = alloc == ARRAY;
// "pointer" and "alloc" get set for non-ptr non-array var
if (vartok && vartok->variable()) {
isPtr = vartok->variable()->isPointer();
isArr = vartok->variable()->isArray();
}
if ((alloc != NO_ALLOC) && ((isPtr || isArr) && !derefValue)) {
return nullptr;
}
}
}

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31 changes: 31 additions & 0 deletions test/testuninitvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2202,6 +2202,37 @@ class TestUninitVar : public TestFixture {
" return i;\n"
"}\n");
ASSERT_EQUALS("", errout_str());


checkUninitVar("void f() {\n"
" char *p = new char;\n"
" p += 1;\n"
" delete (p - 1);\n"
"}\n");
ASSERT_EQUALS("", errout_str());

checkUninitVar("void f() {\n"
" char *buf = (char *)malloc(1);\n"
" if (!buf)\n"
" return NULL;\n"
" buf += buf[0];\n"
" free(buf);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5:15]: (error) Memory is allocated but not initialized: buf[0] [uninitdata]\n", errout_str());

checkUninitVar("void g() {\n"
" int* p = new int;\n"
" p++;\n"
" delete (p - 1);\n"
"}\n");
ASSERT_EQUALS("", errout_str());

checkUninitVar("void g() {\n"
" int* p = new int;\n"
" ++p; // FP\n"
" delete (p - 1);\n"
"}\n");
ASSERT_EQUALS("", errout_str());
}

// class / struct..
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