Fix compiler warnings in trunk

[David Hampton <mythtv@…>]

Compiling trunk generates a number of warning messages. These patches fix the simple warnings.

[David Hampton <mythtv@…>]

Fix for misleading indentation.

[David Hampton <mythtv@…>]

Fix for missing parentheses in math calculation.

[David Hampton <mythtv@…>]

Fix for class variable initialized in different order than its declared

[David Hampton <mythtv@…>]

Remove unused variable

[David Hampton <mythtv@…>]

Remove comparison that will always fail.

[David Hampton <mythtv@…>]

Fix compiler 'unused parameter' error messages.

[Gary Buhrmaster <gary.buhrmaster@…>]

For 0006...., you are likely going to have to get upstream FFMpeg to accept the part of that patch that impacts that code. This project tends to prefer not to carry patches unless absolutely necessary to minimize future merge effort(s).

[David Hampton <mythtv@…>]

Fix 'comparison of unsigned expression' warning.

[David Hampton <mythtv@…>]

Fix 'comparison is always false' warning message.

[David Hampton <mythtv@…>]

Fix 'left fhift of ngative value' warning.

[David Hampton <mythtv@…>]

Fix 'enumeral and non-enumeral type' warning in mythmainwindow.cpp.

[David Hampton <mythtv@…>]

Fix compiler 'enumeral and non-enumeral' warning in recordinginfo.cpp.

[Gary Buhrmaster <gary.buhrmaster@…>]

Re: 0006-...., some (although not necessarily all) of the unused parameters fixes should likely be modified to follow the "Coding Standards" document which states:

Unused parameters Functions that have to satisfy a given interface definition sometimes have parameters that are not used. The name of an unused parameter should be put in a comment to document that the parameter is intentionally unused in such a way that using it anyway will not work. If the function does not have to follow such an interface definition the parameter should simply be removed.

So, for a specific example, a "func(int a, int b)" should turn into a "func(int /* a */, int /* b */)" if a and b are not used, OR the coding standard document needs to be updated.

[David Hampton <mythtv@…>]

Commenting out the variable name is a harder restriction than using the Q_UNUSED() macro. The former prevents any accidental use of the variable in the function, while the latter simply shuts up the compiler by generating a fake reference to the variable. I.E. Q_UNUSED(x) generates "(void)x". I used the macro as I thought that was "the Qt way", but I'm happy to rework the patch if that's what the devs would like.

[Karl Egly]

Replying to David Hampton <mythtv@…>:

the latter simply shuts up the compiler by generating a fake reference to the variable.

David, thanks for joining in and helping with handling the heaps of compiler warnings.

The goal is to silence false positives and to fix all bugs that are pointed out by the warnings. Just shutting the compiler up may make it harder to actually identify genuine bugs.

Here's an example from audioconvert.h:

    bool operator==(AudioConvert& rhs) const
    { return m_in == rhs.m_in && m_out == rhs.m_out; }
    bool operator!=(AudioConvert& rhs) const
-   { return m_in != m_out; }
+   { Q_UNUSED(rhs); return m_in != m_out; }

These are binary operators. And one of them is completely ignoring the right-hand-side symbol. That looks very much like a real bug.

A better fix would be mimicking the operator== like this (just making it up on the fly):

    bool operator==(AudioConvert& rhs) const
    { return m_in == rhs.m_in && m_out == rhs.m_out; }
    bool operator!=(AudioConvert& rhs) const
-   { return m_in != m_out; }
+   { return m_in != rhs.m_in || m_out != rhs.m_out; }

Maybe add some extra parentheses so its easier for a human to read. (not everyone has the precedence order memorized)

    bool operator==(AudioConvert& rhs) const
-   { return m_in == rhs.m_in && m_out == rhs.m_out; }
+   { return (m_in == rhs.m_in) && (m_out == rhs.m_out); }
    bool operator!=(AudioConvert& rhs) const
-   { return m_in != m_out; }
+   { return (m_in != rhs.m_in) || (m_out != rhs.m_out); }

[David Hampton <mythtv@…>]

OK, ignore patch 0006. I'll take another run at the 'unused parameter' warnings.

[David Hampton <mythtv@…>]

Fix unused parameters in trivial functions.

[David Hampton <mythtv@…>]

Fix unused parameter warnings when the variable use is conditionally compiled.

[David Hampton <mythtv@…>]

Remove variable explicitly named dummy.

[David Hampton <mythtv@…>]

Silence unused parameter warnings where the non-use seems intentional.

[David Hampton <mythtv@…>]

Find way to use an 'unused parameter'.

[David Hampton <mythtv@…>]

UPNP serializer patches for intentionally unused variables.

[David Hampton <mythtv@…>]

Clean up unused parameter warnings in mythutil.

[David Hampton <mythtv@…>]

GuideGrid? widget should account for the parent offsets.

[David Hampton <mythtv@…>]

Remove unused code fragment in upnpdevice.cpp.

[David Hampton <mythtv@…>]

Correct the variable names from clipRegion to clipRect.

[David Hampton <mythtv@…>]

Add caller information to the SetAvailableStatus? log message.

[David Hampton <mythtv@…>]

Fix 'unused variable' warning for debug code.

[David Hampton <mythtv@…>]

Remove code fragment whose result is never used.

[David Hampton <mythtv@…>]

Submitted an updated set of patches as ​https://github.com/MythTV/mythtv/pull/134

[Karl Dietz <dekarl@…>]

In 903363043f66c8271cd62d5c9a6bded5a3916fea/mythtv:

Simple unused parameter fixes.

Cherry-picked from a patch by David Hampton

Refs #12996

[Karl Dietz <dekarl@…>]

In 3f20bc5e3152563ba72a57776022aad75b60a3f5/mythtv:

Use parameters that were flagged as 'unused parameter' warnings.

Cherry-picked from a patch by David Hampton

Refs #12996

[Karl Dietz <dekarl@…>]

In b1f4d218a29b2db7735597359997ed6a2a29cbb3/mythtv:

Fix unused parameter warning in UPNP serializers.

Patch by David Hampton

Refs #12996

[Karl Egly]

David, I was cherry picking from your patchset yesterday, when your update came alogn. Can you rebase your PR?

[David Hampton <mythtv@…>]

Pull request rebased off 79844ba.

[David Hampton <mythtv@…>]

In 9506b88b3bc2c3717b32102ece45794fa71f791b/mythtv:

Cleanup gcc and clang warnings generated by -Wextra switch.

This commit fixes a large majority of the warnings generated by using
the -Wextra switch to gcc and clang. It does not fix any warning
related to objects that use QObject as their base class. Enabling the
-Wextra flag by default will occur in a later commit.

Trac: fixes #12996
Github: fixes #134