1605181 - [Automated review] Coverity and clang-tidy warnings when using if constexpr

Status: RESOLVED FIXED

(Developer Infrastructure :: Source Code Analysis, defect, P1)

Description

[Simon Giesecke [:sg] [he/him]]

Phabricator URL: https://phabricator.services.mozilla.com/D57799#1763765

In a construct using if constexpr, I get analyzer warnings from both clang-tidy and coverity, which do not seem to make sense:

Checker reliability is medium, meaning that the false positive ratio is medium.
An "if" statement with no "then" or "else" is suspicious.
The path that leads to this defect is:

    xpcom/tests/gtest/TestThreadUtils.cpp:267:
        stray_semicolon: An "if" statement with no "then" or "else" is suspicious..

    xpcom/tests/gtest/TestThreadUtils.cpp:267:
        remediation: Is the ";" after "if (false)" extraneous, or is the "if" itself unnecessary?.


Warning: Potentially unintended semicolon [clang-tidy: bugprone-suspicious-semicolon]
Checker reliability is high, meaning that the false positive ratio is low.


Warning: Statement should be inside braces [clang-tidy: readability-braces-around-statements]
Checker reliability is high, meaning that the false positive ratio is low.

The offending code is

if constexpr (RunnableFactory::SupportsCopyWithDeletedMove) {
  // ...
}

where RunnableFactory::SupportsCopyWithDeletedMove is a bool depending on a template argument.

Comment 1

[Sylvestre Ledru [:Sylvestre]]

Attachment: Bug 1605181 - 'if constexpr' wasn't supported in clang-tidy r?andi

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7cb37c7ac4e9
'if constexpr' wasn't supported in clang-tidy r=andi

Comment 3

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/7cb37c7ac4e9