blastrock created this revision.
blastrock added reviewers: GorNishanov, EricWF, lewissbaker, tks2103,
modocache, rsmith.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
blastrock edited the summary of this revision.
This started with bug https://bugs.llvm.org/show_bug.cgi?id=41909 which was
fixed by https://reviews.llvm.org/D62550 . In the last comment of the bug
report <https://bugs.llvm.org/show_bug.cgi?id=41909#c3>, Pavel A. Lebedev gives
a code snippet that now makes clang trigger an ICE. This code was broken by
that very commit.
I am no expert, but I tried to follow this comment
<https://reviews.llvm.org/D62550#1526987>. We now build the dependent
statements only if the promise type is not dependent anymore. If it still is, I
guess dependent statements are built in a later pass when all templates are
instantiated.
I have added the second code snippet from the bug and the godbolt snippet from
modocache's answer on the review, this patch seems to fix them all.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D71542
Files:
clang/lib/Sema/TreeTransform.h
clang/test/SemaCXX/coroutines.cpp
Index: clang/test/SemaCXX/coroutines.cpp
===================================================================
--- clang/test/SemaCXX/coroutines.cpp
+++ clang/test/SemaCXX/coroutines.cpp
@@ -734,6 +734,26 @@
}
template void ok_generic_lambda_coawait_PR41909<int>(); // expected-note {{in
instantiation of function template specialization
'ok_generic_lambda_coawait_PR41909<int>' requested here}}
+void ok_generic_lambda_coawait_PR41909_2() {
+ [](auto &arg) -> coro<good_promise_1> { // expected-warning {{expression
result unused}}
+ co_await 12;
+ };
+ [](auto &arg) -> coro<good_promise_1> {
+ co_await 24;
+ }("argument");
+}
+
+template <typename T>
+void ok_generic_lambda_coawait_PR41909_3() {
+ [](auto &arg) -> coro<good_promise_1> { // expected-warning {{expression
result unused}}
+ []() -> coro<good_promise_1> {
+ co_await 12;
+ };
+ co_await 24;
+ };
+}
+template void ok_generic_lambda_coawait_PR41909_3<int>(); // expected-note
{{in instantiation of function template specialization
'ok_generic_lambda_coawait_PR41909_3<int>' requested here}}
+
template<> struct std::experimental::coroutine_traits<int, int, const char**>
{ using promise_type = promise; };
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -7229,16 +7229,7 @@
Builder.ReturnValue = Res.get();
if (S->hasDependentPromiseType()) {
- // PR41909: We may find a generic coroutine lambda definition within a
- // template function that is being instantiated. In this case, the lambda
- // will have a dependent promise type, until it is used in an expression
- // that creates an instantiation with a non-dependent promise type. We
- // should not assert or build coroutine dependent statements for such a
- // generic lambda.
- auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD);
- if (!MD || !MD->getParent()->isGenericLambda()) {
- assert(!Promise->getType()->isDependentType() &&
- "the promise type must no longer be dependent");
+ if (!Promise->getType()->isDependentType()) {
assert(!S->getFallthroughHandler() && !S->getExceptionHandler() &&
!S->getReturnStmtOnAllocFailure() && !S->getDeallocate() &&
"these nodes should not have been built yet");
Index: clang/test/SemaCXX/coroutines.cpp
===================================================================
--- clang/test/SemaCXX/coroutines.cpp
+++ clang/test/SemaCXX/coroutines.cpp
@@ -734,6 +734,26 @@
}
template void ok_generic_lambda_coawait_PR41909<int>(); // expected-note {{in instantiation of function template specialization 'ok_generic_lambda_coawait_PR41909<int>' requested here}}
+void ok_generic_lambda_coawait_PR41909_2() {
+ [](auto &arg) -> coro<good_promise_1> { // expected-warning {{expression result unused}}
+ co_await 12;
+ };
+ [](auto &arg) -> coro<good_promise_1> {
+ co_await 24;
+ }("argument");
+}
+
+template <typename T>
+void ok_generic_lambda_coawait_PR41909_3() {
+ [](auto &arg) -> coro<good_promise_1> { // expected-warning {{expression result unused}}
+ []() -> coro<good_promise_1> {
+ co_await 12;
+ };
+ co_await 24;
+ };
+}
+template void ok_generic_lambda_coawait_PR41909_3<int>(); // expected-note {{in instantiation of function template specialization 'ok_generic_lambda_coawait_PR41909_3<int>' requested here}}
+
template<> struct std::experimental::coroutine_traits<int, int, const char**>
{ using promise_type = promise; };
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -7229,16 +7229,7 @@
Builder.ReturnValue = Res.get();
if (S->hasDependentPromiseType()) {
- // PR41909: We may find a generic coroutine lambda definition within a
- // template function that is being instantiated. In this case, the lambda
- // will have a dependent promise type, until it is used in an expression
- // that creates an instantiation with a non-dependent promise type. We
- // should not assert or build coroutine dependent statements for such a
- // generic lambda.
- auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD);
- if (!MD || !MD->getParent()->isGenericLambda()) {
- assert(!Promise->getType()->isDependentType() &&
- "the promise type must no longer be dependent");
+ if (!Promise->getType()->isDependentType()) {
assert(!S->getFallthroughHandler() && !S->getExceptionHandler() &&
!S->getReturnStmtOnAllocFailure() && !S->getDeallocate() &&
"these nodes should not have been built yet");
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