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Add -Wcast-calling-convention to warn when casting away calling conventions

Authored by rnk on Feb 17 2016, 1:25 PM.



This only warns on casts of the address of a function defined in the
current TU. In this case, the fix is likely to be local and the warning

Here are some things we could experiment with in the future:

  • Fire on declarations as well as definitions
  • Limit the warning to non-void function prototypes
  • Limit the warning to mismatches of caller and callee cleanup CCs

This warning is currently off by default while we study its usefulness.

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rnk updated this revision to Diff 48234.Feb 17 2016, 1:25 PM
rnk retitled this revision from to Add -Wcast-calling-convention to warn when casting away calling conventions.
rnk updated this object.
rnk added reviewers: thakis, rtrieu.
rnk added a subscriber: cfe-commits.
thakis edited edge metadata.Feb 17 2016, 1:40 PM


294 ↗(On Diff #48234)

nit: since this isn't referenced in this file, consider using an unnamed inline InGroup<DiagGroup<"cast-calling-convention"> in the other file instead

6515 ↗(On Diff #48234)

Maybe add ", likely to abort at runtime" to communicate the gravity of the situation better.

6516 ↗(On Diff #48234)

I'd build a large codebase of your choice with this enabled and see how it does. If it does well I'd land it default-on. (I spent some time enabling DefaultIgnore warnings that nobody turned on after they landed recently, and I'd prefer to not having to do this for this warning too :-) )

1762 ↗(On Diff #48234)

If it's an inline function in a header, would we want to warn? Should this check if the body's SourceLocation is from the main file?

1775 ↗(On Diff #48234)

Consider doing something like r164858 did to see if there's a define for the calling convention (WINAPI or what have you) and suggest that instead

rtrieu added inline comments.Feb 23 2016, 3:52 PM
1729 ↗(On Diff #48234)

Capitalize Diagnose like the other Diagnose functions in the file.

1752–1753 ↗(On Diff #48234)

Which UnaryOperator are you attempting to strip off here? This one will strip off every UnaryOperator.

1769–1773 ↗(On Diff #48234)

Usually in Sema, we uses a SmallVector backed ostream for making custom strings.

SmallString<64> CCAttrText;
llvm::raw_svector_ostream OS(CCAttrText);
OS << "some string";
rnk updated this revision to Diff 56802.May 10 2016, 1:44 PM
rnk marked 3 inline comments as done.
rnk edited edge metadata.
  • address comments
rnk added inline comments.May 10 2016, 1:49 PM
294 ↗(On Diff #48234)

Sure. I dono, I never really liked that style since it makes it harder to add it to a group later.

6516 ↗(On Diff #48234)

My attempt to bait you into doing this work has failed. :) I'd still like to land it as ignored-by-default so I can run this warning across Chromium with a try job instead of doing it locally on my workstation. Sound good?

1752–1753 ↗(On Diff #48234)

Oops, added a test for that.

1762 ↗(On Diff #48234)

Yeah, we do want to warn even if it's from a header. If it were defined elsewhere with a different convention, that'd be an ODR violation.

1775 ↗(On Diff #48234)

Done, that was fun. :)

thakis accepted this revision.May 10 2016, 1:55 PM
thakis edited edge metadata.
This revision is now accepted and ready to land.May 10 2016, 1:55 PM
This revision was automatically updated to reflect the committed changes.