Skip to content

Partial fix for #15048 Inconsistent error severity for uninitvar #8966

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
chrchr-github wants to merge 5 commits into
base: main
Choose a base branch
from
+19 −1
Open

Partial fix for #15048 Inconsistent error severity for uninitvar #8966

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
a6863fc
Update checkuninitvar.cpp
chrchr-github Oct 26, 2026
815f861
Update testuninitvar.cpp
chrchr-github Oct 26, 2026
a0b5d15
Fix
web-flow Oct 26, 2026
699ea55
Undo
web-flow Oct 26, 2026
fe389d3
Fix
web-flow Oct 26, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion lib/checkuninitvar.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1593,7 +1593,7 @@ void CheckUninitVarImpl::uninitvarError(const Token* tok, const ValueFlow::Value
const std::string& varname = ltok ? ltok->expressionString() : "x";
ErrorPath errorPath = v.errorPath;
errorPath.emplace_back(tok, "");
auto severity = v.isKnown() ? Severity::error : Severity::warning;
auto severity = v.isKnown() && !v.conditional ? Severity::error : Severity::warning;

@dmcppcheck dmcppcheck Oct 31, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

AI review

conditional is not a reliable sign that the read is only possibly uninitialized. Here it gets set depending on what follows the if.

  • int i; if (b) return i; return 0; still gives error.
  • int i; if (b) return i; i = 1; return i; now gives warning.
  • if (b) g(i); i = 1; g(i); is also demoted to warning.

In each case the read inside the branch is uninitialized every time it executes, so these are definite bugs that used to be errors. The patch makes the severity less consistent instead of more.

auto certainty = v.isInconclusive() ? Certainty::inconclusive : Certainty::normal;
if (v.subexpressions.empty()) {
reportError(std::move(errorPath),
Expand Down
18 changes: 18 additions & 0 deletions test/testuninitvar.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,7 @@ class TestUninitVar : public TestFixture {
TEST_CASE(valueFlowUninitBreak);
TEST_CASE(valueFlowUninitStructMembers);
TEST_CASE(valueFlowUninitForLoop);
TEST_CASE(valueFlowUninitErrorPath);
TEST_CASE(uninitvar_ipa);
TEST_CASE(uninitvar_memberfunction);
TEST_CASE(uninitvar_nonmember); // crash in ycmd test
Expand Down Expand Up @@ -7945,6 +7946,23 @@ class TestUninitVar : public TestFixture {
ASSERT_EQUALS("", errout_str());
}

void valueFlowUninitErrorPath()
{
setMultiline();

valueFlowUninit("void f(bool b) {\n"
" int i;\n"
" if (b)\n"
" return i;\n"
" i = 1;\n"
" return i;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4:16]: warning: Uninitialized variable: i [uninitvar]\n"

@dmcppcheck dmcppcheck Oct 31, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

AI review

This expectation locks in a downgrade: return i; inside if (b) always reads an uninitialized i, and base reports it as an error. If return 0; replaces the i = 1; return i; tail, the same read is still reported as an error, so this test documents the inconsistency instead of fixing it.

"[test.cpp:3:9]: note: Assuming condition is true\n"
"[test.cpp:4:16]: note: Uninitialized variable: i\n",
errout_str());
}

void uninitvar_memberfunction() {
// # 8715
valueFlowUninit("struct C {\n"
Expand Down
Loading