On Tue, Jul 28, 2020 at 5:45 PM Marek Polacek via Gcc-patches < gcc-patches@gcc.gnu.org> wrote:
> In Bugzilla, for the c++ component, we currently have over 3200 open > bugs. In > my experience, a good amount of them have already been fixed; my periodical > sweeps always turn up a bunch of PRs that had already been fixed > previously. > Sometimes my sweeps are more or less random, but more often than not I'm > just > looking for duplicates of an existing PR. Sometimes the reason the already > fixed PRs are still open is because a PR that was fixed had duplicates > that we > didn't catch earlier when confirming the PR. Sometimes a PR gets fixed as > a > side-effect of fixing another PR. Manual sweeps are tedious and > time-consuming > because often you need to grab the test from the Bugzilla yet again (and > sometimes there are multiple tests). Even if you find a PR that was > fixed, you > still need to bisect the fix and perhaps add the test to our testsuite. > That's > draining and since the number of bugs only increases, never decreases, it > is not > sustainable. > > So I've started a personal repo where I've gathered dozens of tests and > wrote a > script that just compiles every test in the repo and reports if anything > changed. One line from it: > > pr=59798; $cxx $o -c $pr.C 2>&1 | grep -qE 'internal compiler error' || > echo -e "$pr: ${msg_ice}" > > This has major drawbacks: you have to remember to run this manually, keep > updating it, and it's yet another repo that people interested in this would > have to clone, but the worst thing is that typically you would only > discover > that a patch fixed a different PR long after the patch was committed. And > quite likely it wasn't even your patch. We know that finding problems > earlier > in the developer workflow reduces costs; if we can catch this before the > original developer commits & pushes the changes, it's cheaper, because the > developer already understands what the patch does. > > A case in point: https://gcc.gnu.org/PR58156 which has been fixed recently > by an unrelated (?) patch. Knowing that the tsubst_pack_expansion hunk in > the patch had this effect would probably have been very useful. More > testing > will lead to a better compiler. > > Another case: https://gcc.gnu.org/35098 which was fixed 12 years (!) after > it was reported by a different change. > > Or another: https://gcc.gnu.org/91525 where the patch contained a test, > but > that was ice-on-invalid, whereas the test in PR91525 was ice-on-valid. > > To alleviate some of these problems, I propose that we introduce a means > to our > DejaGNU infrastructure that allows adding tests for old bugs that have not > been > fixed yet, and re-introduce the keyword monitored (no longer used for > anything > -- I think Volker stepped away) to the GCC Bugzilla to signal that a PR is > tracked in the testsuite. I don't want any unnecessary moving tests > around, so > the tests would go where they would normally go; they have to be reduced > and > have proper targets, etc. Having such tests in the testsuite means that > when > something changes, you will know immediately, before you push any changes. > > My thinking is that for: > > * rejects-valid: use the existing dg-xfail-if > Or dg-excess-errors, or xfailed dg-bogus. > * accepts-valid: use the new dg-accepts-invalid > xfailed dg-error should cover this case. > * ICEs: use the new dg-ice. > This seems like a good addition. > dg-ice can be used like this: > > // { dg-ice "build_over_call" { target c++11 } } > > and it means that if the test still ICEs, you'll get a quiet XFAIL. If the > ICE is fixed, you'll get an XPASS; if the ICE is gone but there are errors, > you'll get an XPASS + FAIL. Then you can close the old PR. > > Similarly, dg-accepts-invalid: > > // { dg-accepts-invalid "PR86500" } > > means that if the test still compiles without errors, you'll get a quiet > XFAIL. > If we start giving errors, you'll get an XPASS. > > If the bug is fixed, simply remove the directive. > > The patch implementing these new directives is appended. Once/if this is > accepted, I can start adding the old tests we have in our Bugzilla. (I'm > only concerned about the c++ component, if that wasn't already clear.) > > The question is what makes the bug "old": is it one year without it being > assigned? 6 months? 3 months? Note: I *don't* propose to add every test > for > every new PR, just the reasonably old ones that are useful/important. Such > additions should be done in batches, so that we don't have dozens of > commits, > each of them merely adding a single test. > > We will still have a surfeit of bugs that we've given short shrift to, but > let's at least automate what we can. The initial addition of the relevant > old(-ish) tests won't of course happen automagically, but it's a price I'm > willing to pay. My goal here isn't merely to reduce the number of open > PRs; > it is to improve the testing of the compiler overall. > > Thoughts? > > Bootstrapped/regtested on x86_64-pc-linux-gnu. > > [PATCH] testsuite: Introduce dg-ice and dg-accepts-invalid. > > gcc/ChangeLog: > > * doc/sourcebuild.texi: Document dg-ice and dg-accepts-invalid. > > gcc/testsuite/ChangeLog: > > * lib/gcc-dg.exp (gcc-dg-test-1): Handle dg-ice and > dg-accepts-invalid. > * lib/prune.exp (prune_ices): New. > * lib/target-supports-dg.exp (dg-accepts-invalid, dg-ice): New. > --- > gcc/doc/sourcebuild.texi | 19 +++++++ > gcc/testsuite/lib/gcc-dg.exp | 39 +++++++++++++- > gcc/testsuite/lib/prune.exp | 9 ++++ > gcc/testsuite/lib/target-supports-dg.exp | 69 ++++++++++++++++++++++++ > 4 files changed, 134 insertions(+), 2 deletions(-) > > diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi > index a7a922d84a2..636d21d30dd 100644 > --- a/gcc/doc/sourcebuild.texi > +++ b/gcc/doc/sourcebuild.texi > @@ -1172,6 +1172,16 @@ Expect the execute step of a test to fail if the > conditions (which are > the same as for @code{dg-skip-if}) are met. > @end table > > +@subsubsection Expect the compiler to crash > + > +@table @code > +@item @{ dg-ice @var{comment} [@{ @var{selector} @} [@{ > @var{include-opts} @} [@{ @var{exclude-opts} @}]]] @} > +Expect the compiler to crash with an internal compiler error and return > +a nonzero exit status if the conditions (which are the same as for > +@code{dg-skip-if}) are met. Used for tests that test bugs that have not > been > +fixed yet. > +@end table > + > @subsubsection Expect the test executable to fail > > @table @code > @@ -1234,6 +1244,15 @@ has the same effect as @samp{target}. > > @item @{ dg-prune-output @var{regexp} @} > Prune messages matching @var{regexp} from the test output. > + > +@table @code > +@item @{ dg-accepts-invalid @var{comment} [@{ @var{selector} @} [@{ > @var{include-opts} @} [@{ @var{exclude-opts} @}]]] @} > +Expect the compiler to accept the test (even though it should be rejected > with > +a compile-time error), if the conditions (which are the same as for > +@code{dg-skip-if}) are met. Used for tests that test bugs that have not > been > +fixed yet. > +@end table > + > @end table > > @subsubsection Verify output of the test executable > diff --git a/gcc/testsuite/lib/gcc-dg.exp b/gcc/testsuite/lib/gcc-dg.exp > index 45d97024883..6478eda283b 100644 > --- a/gcc/testsuite/lib/gcc-dg.exp > +++ b/gcc/testsuite/lib/gcc-dg.exp > @@ -308,13 +308,48 @@ proc gcc-dg-test-1 { target_compile prog do_what > extra_tool_flags } { > verbose "$target_compile $prog $output_file $compile_type $options" 4 > set comp_output [$target_compile "$prog" "$output_file" > "$compile_type" $options] > > + global expect_ice > # Look for an internal compiler error, which sometimes masks the fact > # that we didn't get an expected error message. XFAIL an ICE via > # dg-xfail-if and use { dg-prune-output ".*internal compiler error.*" > } > # to avoid a second failure for excess errors. > - if [string match "*internal compiler error*" $comp_output] { > + # "Error reporting routines re-entered" ICE says "Internal" rather > than > + # "internal", so match that too. > + if [string match {*[Ii]nternal compiler error*} $comp_output] { > upvar 2 name name > - fail "$name (internal compiler error)" > + if { $expect_ice == 0 } { > + fail "$name (internal compiler error)" > + } else { > + # We expected an ICE and we got it. Emit an XFAIL. > + setup_xfail "*-*-*" > + fail "$name (internal compiler error)" > + clear_xfail "*-*-*" > + # Prune the ICE from the output. > + set comp_output [prune_ices $comp_output] > + } > + } else { > + upvar 2 name name > + global accepts_invalid > + if { $expect_ice == 1 } { > + # We expected an ICE but we didn't get it. We want an XPASS, so > + # call setup_xfail to set xfail_flag. > + setup_xfail "*-*-*" > + pass "$name (internal compiler error)" > + clear_xfail "*-*-*" > + } elseif { $accepts_invalid == 1 } { > + if [string match {*error: *} $comp_output] { > + # We expected that this test be (wrongly) accepted, but now > we have > + # seen error(s). Issue an XPASS to signal that. > + setup_xfail "*-*-*" > + pass "$name (accepts invalid)" > + clear_xfail "*-*-*" > + } else { > + # This test is still (wrongly) accepted. Just emit an XFAIL. > + setup_xfail "*-*-*" > + fail "$name (accepts invalid)" > + clear_xfail "*-*-*" > + } > + } > } > > if { $do_what == "repo" } { > diff --git a/gcc/testsuite/lib/prune.exp b/gcc/testsuite/lib/prune.exp > index 1c776249f1a..58a739684a5 100644 > --- a/gcc/testsuite/lib/prune.exp > +++ b/gcc/testsuite/lib/prune.exp > @@ -118,6 +118,15 @@ proc prune_file_path { text } { > return $text > } > > +# Prune internal compiler error messages, including the "Please submit..." > +# footnote. > + > +proc prune_ices { text } { > + regsub -all "(^|\n)\[^\n\]*: internal compiler error:.*for > instructions\[^\n\]*" $text "" text > + regsub -all "(^|\n|')*Internal compiler error:.*for > instructions\[^\n\]*" $text "" text > + return $text > +} > + > # Provide a definition of this if missing (delete after next dejagnu > release). > > if { [info procs prune_warnings] == "" } then { > diff --git a/gcc/testsuite/lib/target-supports-dg.exp > b/gcc/testsuite/lib/target-supports-dg.exp > index 2a21424b890..765f3a2e27a 100644 > --- a/gcc/testsuite/lib/target-supports-dg.exp > +++ b/gcc/testsuite/lib/target-supports-dg.exp > @@ -495,6 +495,75 @@ proc dg-shouldfail { args } { > } > } > > +# Record whether the compiler is expected (at the moment) to ICE. > +# Used for tests that test bugs that have not been fixed yet. > + > +set expect_ice 0 > +set accepts_invalid 0 > + > +proc dg-ice { args } { > + # Don't bother if we're already skipping the test. > + upvar dg-do-what dg-do-what > + if { [lindex ${dg-do-what} 1] == "N" } { > + return > + } > + > + global accepts_invalid > + # Can't be combined with dg-accepts-invalid. > + if { $accepts_invalid == 1 } { > + error "dg-ice: cannot be combined with dg-accepts-invalid" > + return > + } > + > + global expect_ice > + > + set args [lreplace $args 0 0] > + if { [llength $args] > 1 } { > + set selector [list target [lindex $args 1]] > + if { [dg-process-target-1 $selector] == "S" } { > + # The target matches, now check the flags. > + if [check-flags $args] { > + set expect_ice 1 > + } > + } > + } else { > + set expect_ice 1 > + } > +} > + > +# Record whether the compiler should reject the testcase with an error, > +# but currently doesn't do so. Used for accepts-invalid bugs. > + > +proc dg-accepts-invalid { args } { > + # Don't bother if we're already skipping the test. > + upvar dg-do-what dg-do-what > + if { [lindex ${dg-do-what} 1] == "N" } { > + return > + } > + > + global expect_ice > + # Can't be combined with dg-ice. > + if { $expect_ice == 1 } { > + error "dg-accepts-invalid: cannot be combined with dg-ice" > + return > + } > + > + global accepts_invalid > + > + set args [lreplace $args 0 0] > + if { [llength $args] > 1 } { > + set selector [list target [lindex $args 1]] > + if { [dg-process-target-1 $selector] == "S" } { > + # The target matches, now check the flags. > + if [check-flags $args] { > + set accepts_invalid 1 > + } > + } > + } else { > + set accepts_invalid 1 > + } > +} > + > # Intercept the call to the DejaGnu version of dg-process-target to > # support use of an effective-target keyword in place of a list of > # target triplets to xfail or skip a test. > > base-commit: f3665bd1111c1799c0421490b5e655f977570354 > -- > 2.26.2 > >