Second Lit tests C++11 compatibility patch: using preprocessor to filter expected-error
Li, Charles via cfe-commits
cfe-commits at lists.llvm.org
Mon Aug 17 18:27:14 PDT 2015
Hi Richard,
I have modified the “expected-“ lines as you requested.
Cheers,
Charles
From: metafoo at gmail.com [mailto:metafoo at gmail.com] On Behalf Of Richard Smith
Sent: Monday, August 17, 2015 5:41 PM
To: Li, Charles
Cc: Justin Bogner; cfe-commits at lists.llvm.org
Subject: Re: Second Lit tests C++11 compatibility patch: using preprocessor to filter expected-error
On Mon, Aug 17, 2015 at 5:15 PM, Li, Charles via cfe-commits <cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>> wrote:
Hi Richard and Justin,
> What's the upside to this approach? AFAICT it makes the test harder to read and errors less informative due to pointing at the wrong lines, but (at least in switch-1.c) it doesn't actually reduce any code duplication or anything like that. What is this gaining us apart from not having to create one more file?
Thank you Justin.
Our original intention was to get the Lit tests to run at any default C++ dialect.
We first discovered that FileCheck does not respect #ifdef since it does not know about pre-defined macros.
So we figured if we preprocess the source first, the preprocessor will filter the #ifdef sections and the output will feed nicely into FileCheck.
The upside is the test can run at the default dialect in addition to explicitly specified dialect.
The downside is, as you mentioned, the errors diagnostics would point to the wrong lines.
> The only thing novel about this approach is using the preprocessor to achieve it. -verify *does* respect #ifdef, and we have a lot of tests that rely on that.
Thank you Richard.
We erroneously assumed that “// CHECK:” and “// expected-error” work the same way.
But now we realized that assumption was wrong.
In light this discussion, I have removed the preprocessing to temporary step for all tests.
The attached patch (Lit_24.patch) revised 2 test fixes relative to the previous patch (Lit_22.patch)
test/Analysis/temp-obj-dtors-cfg-output.cpp
This test uses FileCheck to check for CFG dump.
Instead of using #ifdef for the dialect specific “// CHECK:” lines,
I have created 2 check-prefixes “CXX11” and “CXX98”.
The pre-process step have been removed.
test/Sema/switch-1.c
This test uses –verify to check for integer overflows diagnostics.
The pre-process step have been removed.
The #ifdef is kept since it works with -verify.
Instead of duplicating the code, you can do this:
case blah:
#if __cplusplus >= 201103L
// expected-error at -2 {{error 2 lines above}}
#else
// expected-error at -4 {{error 4 lines above}}
#endif
Please let me know how you feel about this patch.
Sincerely,
Charles
From: metafoo at gmail.com<mailto:metafoo at gmail.com> [mailto:metafoo at gmail.com<mailto:metafoo at gmail.com>] On Behalf Of Richard Smith
Sent: Monday, August 17, 2015 1:07 PM
To: Li, Charles
Cc: cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>
Subject: Re: Second Lit tests C++11 compatibility patch: using preprocessor to filter expected-error
On Mon, Aug 17, 2015 at 9:56 AM, Li, Charles via cfe-commits <cfe-commits at lists.llvm.org<mailto:cfe-commits at lists.llvm.org>> wrote:
Hi Clang developers,
We here at Sony are continuing to update the Lit tests for C++ dialects compatibility.
Attached is the second patch. (As a reference, here is the link to the discussion on the previous Lit patch. http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20150727/134667.html)
In this second patch, there is 1 complicated change and 3 simple changes.
Here is the complicated change first.
test/Sema/switch-1.c
This test verifies the diagnostics for integer overflows.
Due to C++11’s more strict requirements on constant-expressions in 5.19p2 [expr.const],
The diagnostics have changed from “overflow in expression” to “not a constant expression”.
Usually we would create a C++11 version of the switch-1.c file.
But here we propose a novel approach to “#ifdef” the expected diagnostics. (We hope to use this approach for all similar cases in the future.)
Normally ‘// expected-error’ does not honor any ‘#ifdef’.
But if we first preprocess the source into a temporary file, only the valid ‘#ifdef’ sections remain.
We then run the preprocessed file at the desired dialect.
The main downside to this approach is If the test fails, the errors are reported on the temporary file, not on the original file, and the line numbers of these two files do not match
The only thing novel about this approach is using the preprocessor to achieve it. -verify *does* respect #ifdef, and we have a lot of tests that rely on that.
Here are the simple changes.
test/Analysis/temp-obj-dtors-cfg-output.cpp
This test verifies CFG dump for temporary destructors
C++11 no longer has the following implicit cast.
(ImplicitCastExpr, NoOp, const struct D)
We modified the test using the #ifdef approach to have the preprocessor generate the desired CHECK lines.
test/CodeCompletion/ordinary-name.cpp
This test verifies for code completion patterns.
Since C++11 has more keywords than C++98,
We made this test to be C++98 specific, and create a separate C++11 version.
test/CodeCompletion/ordinary-name-cxx11.cpp
This is the C++11 specific version of the code completion.
This test added patterns for the following keywords:
char16, char32, noexcept, nullptr, sizeof...,
auto, decltype, char16_t, char32_t
test/Sema/thread-specifier.c
Tests for __thread specifier at various C++ dialects
We made the default RUN line explicit to be at –std=c++98
If there is anything that seems confusing to you, please let me know.
I would be more than happy to expand on the reasons for the these changes.
Thanks,
Charles
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