1443448 - [clang-tidy] Disallow non-empty inline virtual methods

Status: NEW

(Developer Infrastructure :: Source Code Analysis, enhancement)

Description

[Jonathan Watt [:jwatt]]

Chromium has a checker for this:

https://www.chromium.org/developers/coding-style/chromium-style-checker-errors#TOC-Virtual-Method-Out-of-lining

It seems like they got good code size reductions. See the comments on:

https://codereview.chromium.org/5741001/

for example.

Comment 1

[Sylvestre Ledru [:Sylvestre]]

Code available here:
https://chromium.googlesource.com/chromium/src/tools/clang/+/2cf23bd023e0692f00f023970c7e673490dffa43/plugins/FindBadConstructs.cpp

Comment 2

[Jonathan Watt [:jwatt]]

I wonder if they'd be willing to convert it to clang-tidy and upstream it?

Comment 3

[Andi [:andi]]

As the code is right now, there must be some fundamental modifications in order to upstream it to clang-tidy, because the current analysis doesn't use a matcher to match a 'CXXFuncDecl' inside a 'CXXRecordDecl', it still relies on hooking up on a ASTConsumer that's why they used the clang-plugin architecture. 
TBH I'm not even sure that the code exists in the latest revisions of that folder.

Comment 4

[Chris Peterson [:cpeterson]]

While not quite the same warning, clang's -Wweak-vtable flag can report when a class's virtual functions are all inline. Without a "home" translation unit for the class's out-of-line vtable, a duplicate vtable will be emitted in every translation unit that references the class. This warning is very noisy.

https://clang.llvm.org/docs/DiagnosticsReference.html#wweak-vtables