803695 - TestCOMPtrEq.cpp:78:18: warning: self-comparison always evaluates to true [-Wtautological-compare]

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Daniel Holbert [:dholbert]]

I tried setting FAIL_ON_WARNINGS in /xpcom/tests, and it's fine on Linux w/ GCC, but on Mac we trigger these:
{

../../../../xpcom/tests/TestCOMPtrEq.cpp:78:18: error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
              (r == r) &&
                 ^
../../../../xpcom/tests/TestCOMPtrEq.cpp:94:19: error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
              (rc == rc) &&
                  ^
../../../../xpcom/tests/TestCOMPtrEq.cpp:102:19: error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
              (rk == rk) &&
                  ^
../../../../xpcom/tests/TestCOMPtrEq.cpp:110:20: error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
              (rkc == rkc) &&
                   ^
../../../../xpcom/tests/TestCOMPtrEq.cpp:118:18: error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
              (d == d) &&
                 ^
}
https://tbpl.mozilla.org/php/getParsedLog.php?id=16275787&tree=Try

The variables that it's complaining about are all _pointers_ (not objects), so we aren't exercising any fancy operator== behavior.  Here's a snippet from MXR, demonstrating that:
> 52     nsICOMPtrEqTestFoo* r = 0;
[...]
> 54     const nsICOMPtrEqTestFoo* rc = 0;
> 55     nsICOMPtrEqTestFoo* const rk = 0;
> 56     const nsICOMPtrEqTestFoo* const rkc = 0;
> 57     nsICOMPtrEqTestFoo* d = s;
http://mxr.mozilla.org/mozilla-central/source/xpcom/tests/TestCOMPtrEq.cpp

So, I propose we just remove these self-comparisons.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: fix & mark directory as warning-free

Looks like dbaron wrote this test back in 2001 (in https://bugzilla.mozilla.org/show_bug.cgi?id=65664#c12 ), so requesting r?dbaron.

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 673446 [details] [diff] [review]
fix & mark directory as warning-free

r=dbaron

Comment 3

[Daniel Holbert [:dholbert]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/4ae3fd8d62f4

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/4ae3fd8d62f4