[CI-NOTIFY]: TCWG Bisect tcwg_bmk_stm32/gnu_eabi-master-arm_eabi-coremark-Os - Build # 12 - Fixed! - linaro-toolchain

28 Jul 2021

Successfully identified regression in *gcc* in CI configuration tcwg_bmk_gnu_eabi_stm32/gnu_eabi-master-arm_eabi-coremark-Os.  So far, this commit has regressed CI configurations:
 - tcwg_bmk_gnu_eabi_stm32/gnu_eabi-master-arm_eabi-coremark-Os
Culprit:
<cut>
commit 784de5292c34e287c848b382b431599b818ea76e
Author: Jakub Jelinek jakub@redhat.com
Date:   Fri Apr 16 09:34:26 2021 +0200
c++: Fix up C++23 [] <...> requires primary -> type {} parsing [PR99850]
The requires clause parsing has code to suggest users wrapping
    non-primary expressions in (), so if it e.g. parses a primary expression
    and sees it is followed by ++, --, ., ( or -> among other things it
    will try to reparse it as assignment expression or what and if that works
    suggests wrapping it inside of parens.
    When it is requires-clause that is after <typename T> etc. it already
    has an exception from that as ( can occur in valid C++20 expression there
    - starting the parameters of the lambda.
    In C++23 another case can occur, as the parameters with the ()s can be
    omitted, requires C can be followed immediately by -> which starts a
    trailing return type.  Even in that case, we don't want to parse that
    as C->...
2021-04-16  Jakub Jelinek  jakub@redhat.com
PR c++/99850
            * parser.c (cp_parser_constraint_requires_parens) <case CPP_DEREF>:
            If lambda_p, return pce_ok instead of pce_maybe_postfix.
* g++.dg/cpp23/lambda-specifiers2.C: New test.
</cut>
Results regressed to (for first_bad == 784de5292c34e287c848b382b431599b818ea76e)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--disable-libsanitizer --set gcc_override_configure=--disable-multilib --set gcc_override_configure=--with-cpu=cortex-m4 --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--with-float=hard:
-8
# build_abe newlib:
-6
# build_abe stage2 -- --set gcc_override_configure=--disable-libsanitizer --set gcc_override_configure=--disable-multilib --set gcc_override_configure=--with-cpu=cortex-m4 --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--with-float=hard:
-5
# true:
0
# benchmark -Os_mthumb -- artifacts/build-784de5292c34e287c848b382b431599b818ea76e/results_id:
1
from (for last_good == 20eb7a1891cfd7fa85295a236cebe0322d041edd)
# reset_artifacts:
-10
# build_abe binutils:
-9
# build_abe stage1 -- --set gcc_override_configure=--disable-libsanitizer --set gcc_override_configure=--disable-multilib --set gcc_override_configure=--with-cpu=cortex-m4 --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--with-float=hard:
-8
# build_abe newlib:
-6
# build_abe stage2 -- --set gcc_override_configure=--disable-libsanitizer --set gcc_override_configure=--disable-multilib --set gcc_override_configure=--with-cpu=cortex-m4 --set gcc_override_configure=--with-mode=thumb --set gcc_override_configure=--with-float=hard:
-5
# true:
0
# benchmark -Os_mthumb -- artifacts/build-baseline/results_id:
1
Artifacts of last_good build: https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab...
Results ID of last_good: stm32_STM32L476RGTx/tcwg_bmk_gnu_eabi_stm32/baseline-gnu_eabi-master-arm_eabi-coremark-Os/2215
Artifacts of first_bad build: https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab...
Results ID of first_bad: stm32_STM32L476RGTx/tcwg_bmk_gnu_eabi_stm32/bisect-gnu_eabi-master-arm_eabi-coremark-Os/2252
Build top page/logs: https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab...
Configuration details:
Reproduce builds:
<cut>
mkdir investigate-gcc-784de5292c34e287c848b382b431599b818ea76e
cd investigate-gcc-784de5292c34e287c848b382b431599b818ea76e
git clone https://git.linaro.org/toolchain/jenkins-scripts
mkdir -p artifacts/manifests
curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab... --fail
curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab... --fail
curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab... --fail
chmod +x artifacts/test.sh
# Reproduce the baseline build (build all pre-requisites)
./jenkins-scripts/tcwg_bmk-build.sh @@ artifacts/manifests/build-baseline.sh
# Save baseline build state (which is then restored in artifacts/test.sh)
mkdir -p ./bisect
rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /gcc/ ./ ./bisect/baseline/
cd gcc
# Reproduce first_bad build
git checkout --detach 784de5292c34e287c848b382b431599b818ea76e
../artifacts/test.sh
# Reproduce last_good build
git checkout --detach 20eb7a1891cfd7fa85295a236cebe0322d041edd
../artifacts/test.sh
cd ..
</cut>
History of pending regressions and results: https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/c...
Artifacts: https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab...
Build log: https://ci.linaro.org/job/tcwg_bmk_ci_gnu_eabi-bisect-tcwg_bmk_stm32-gnu_eab...
Full commit (up to 1000 lines):
<cut>
commit 784de5292c34e287c848b382b431599b818ea76e
Author: Jakub Jelinek jakub@redhat.com
Date:   Fri Apr 16 09:34:26 2021 +0200
c++: Fix up C++23 [] <...> requires primary -> type {} parsing [PR99850]
The requires clause parsing has code to suggest users wrapping
    non-primary expressions in (), so if it e.g. parses a primary expression
    and sees it is followed by ++, --, ., ( or -> among other things it
    will try to reparse it as assignment expression or what and if that works
    suggests wrapping it inside of parens.
    When it is requires-clause that is after <typename T> etc. it already
    has an exception from that as ( can occur in valid C++20 expression there
    - starting the parameters of the lambda.
    In C++23 another case can occur, as the parameters with the ()s can be
    omitted, requires C can be followed immediately by -> which starts a
    trailing return type.  Even in that case, we don't want to parse that
    as C->...
2021-04-16  Jakub Jelinek  jakub@redhat.com
PR c++/99850
            * parser.c (cp_parser_constraint_requires_parens) <case CPP_DEREF>:
            If lambda_p, return pce_ok instead of pce_maybe_postfix.
* g++.dg/cpp23/lambda-specifiers2.C: New test.
---
 gcc/cp/parser.c                                 | 13 +++++++++++++
 gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 940751b5f05..dfc9b8251a7 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -28530,7 +28530,20 @@ cp_parser_constraint_requires_parens (cp_parser *parser, bool lambda_p)
       case CPP_PLUS_PLUS:
       case CPP_MINUS_MINUS:
       case CPP_DOT:
+	/* Unenclosed postfix operator.  */
+	return pce_maybe_postfix;
+
       case CPP_DEREF:
+	/* A primary constraint that precedes the lambda-declarator of a
+	   lambda expression is followed by trailing return type.
+
+	      []<typename T> requires C -> void {}
+
+	   Don't try to re-parse this as a postfix expression in
+	   C++23 and later.  In C++20 ( needs to come in between but we
+	   allow it to be omitted with pedwarn.  */
+	if (lambda_p)
+	  return pce_ok;
    /* Unenclosed postfix operator.  */
    return pce_maybe_postfix;
    }
diff --git a/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C b/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C
new file mode 100644
index 00000000000..0cc69bebc64
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/lambda-specifiers2.C
@@ -0,0 +1,7 @@
+// PR c++/99850
+// P1102R2 - Down with ()!
+// { dg-do compile { target c++23 } }
+
+auto l = []<auto> requires true -> void {};
+template <typename...> concept C = true;
+auto m = []<typename... Ts> requires (C<Ts> && ...) -> void {};
</cut>

    