[cfe-dev] Proposed new policy for tests which are looking at the output of -ast-dump

[Roman Lebedev via cfe-dev]

+1, i support this.

If we won't do that in an organized matter, I suspect, we will be
hitting every one of these bugs sooner or later with/via modules.

Thanks for looking into improving [de]serialization quality!

Roman.

On Sun, Jun 21, 2020 at 5:20 PM Bruno Ricci via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
>
> Hi all!
>
> I would like to propose a new policy for tests which are looking at
> the output of -ast-dump:
>
> Any such test must also look at the output of -ast-dump-all after
> deserialization, or explain why an exception is needed.
>
> Modulo a few differences (the "<undeserialized declarations>"s and the "imported"s)
> the outputs should match. This has already helped to find and fix two serialization
> bugs (one in LambdaExpr fixed in 05843dc6ab97a00cbde7aa4f08bf3692eb83109d, and one
> in ConstantExpr, fixed in e7ce0528202306d8b751f132d9d3a6519ce4e688).
>
> How:
>
> 1) For hand-written tests, strip the "<undeserialized declarations>"s and the
>    "imported"s with sed. For example if the original RUN line is
>
>    // RUN: %clang_cc1 -ffoo -fbar -ast-dump -ast-dump-filter Whatever %s \
>    // RUN: | FileCheck %s --strict-whitespace
>
>    then add the following RUN lines:
>
>    // RUN: %clang_cc1 -ffoo -fbar -emit-pch -o %t %s
>    // RUN: %clang_cc1 -x c++ -ffoo -fbar -include-pch %t -ast-dump-all -ast-dump-filter Whatever /dev/null \
>    // RUN: | sed -e "s/ <undeserialized declarations>//" -e "s/ imported//" \
>    // RUN: | FileCheck %s --strict-whitespace
>
> 2) For tests autogenerated with make-ast-dump-check.sh, generate the test with the
>    recently added option "generate_serialization_test=1".
>
> This will of course not find every serialization bugs. However given the tiny additional
> cost (a few RUN lines), I don't see any downsides.
>
> Thanks!
>
> Bruno Ricci
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