ahatanak created this revision.
ahatanak added reviewers: tahonermann, erichkeane, aaron.ballman, shafik,
Bigcheese, arphaman.
ahatanak added a project: clang.
Herald added a project: All.
ahatanak requested review of this revision.
This is needed to fix https://github.com/llvm/llvm-project/issues/60155.
An assertion in `tryCaptureVariable` fails because `SubstDefaultArgument`
pushes the context for the lambda's function operator, but the LambdaScopeInfo
isn't being pushed to the stack.
It appears that the assertion started to fail in
4409a83c293537e22da046b54e9f69454cdd3dca
<https://reviews.llvm.org/rG4409a83c293537e22da046b54e9f69454cdd3dca>, which
delays instantiation of default arguments. By the time the default arguments
are instantiated, which happens after `inherited::TransformLambdaExpr` is
called, the lambda scope has already been popped.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D143109
Files:
clang/lib/Sema/SemaTemplateInstantiate.cpp
clang/test/SemaCXX/lambda-default-arg.cpp
Index: clang/test/SemaCXX/lambda-default-arg.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/lambda-default-arg.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=c++17 -verify -fsyntax-only %s
+
+template <class T> bool test0() {
+ constexpr float a = 1e-5f;
+ return [=](float b = a) -> bool {
+ return a < 0;
+ }();
+}
+
+bool b0 = test0<int>();
+
+template <class T> bool test1() {
+ float a = 1e-5f;
+ return [=](float b = a) -> bool { // expected-error {{default argument
references local variable 'a'}}
+ return a < 0;
+ }();
+}
+
+bool b1 = test1<int>();
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1348,6 +1348,13 @@
Expr *UninstExpr = PVD->getUninstantiatedDefaultArg();
// FIXME: Obtain the source location for the '=' token.
SourceLocation EqualLoc = UninstExpr->getBeginLoc();
+
+ // Push an empty lambda scope. This is needed as SubstDefaultArgument
+ // pushes the context for the lambda's function call operator and we
+ // need to keep the contexts and the function scopes in sync.
+ getSema().PushLambdaScope();
+ Sema::FunctionScopeRAII FuncScopeCleanup(getSema());
+
if (SemaRef.SubstDefaultArgument(EqualLoc, PVD, TemplateArgs)) {
// If substitution fails, the default argument is set to a
// RecoveryExpr that wraps the uninstantiated default argument so
Index: clang/test/SemaCXX/lambda-default-arg.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/lambda-default-arg.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=c++17 -verify -fsyntax-only %s
+
+template <class T> bool test0() {
+ constexpr float a = 1e-5f;
+ return [=](float b = a) -> bool {
+ return a < 0;
+ }();
+}
+
+bool b0 = test0<int>();
+
+template <class T> bool test1() {
+ float a = 1e-5f;
+ return [=](float b = a) -> bool { // expected-error {{default argument references local variable 'a'}}
+ return a < 0;
+ }();
+}
+
+bool b1 = test1<int>();
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1348,6 +1348,13 @@
Expr *UninstExpr = PVD->getUninstantiatedDefaultArg();
// FIXME: Obtain the source location for the '=' token.
SourceLocation EqualLoc = UninstExpr->getBeginLoc();
+
+ // Push an empty lambda scope. This is needed as SubstDefaultArgument
+ // pushes the context for the lambda's function call operator and we
+ // need to keep the contexts and the function scopes in sync.
+ getSema().PushLambdaScope();
+ Sema::FunctionScopeRAII FuncScopeCleanup(getSema());
+
if (SemaRef.SubstDefaultArgument(EqualLoc, PVD, TemplateArgs)) {
// If substitution fails, the default argument is set to a
// RecoveryExpr that wraps the uninstantiated default argument so
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