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Trying to use structure binding with a structure that doesn't implement
std::tuple_size, should unpack the data members. When the struct is a
template though, clang might hit an assertion (if the type has not been
completed before), because CXXRecordDecl::DefinitionData is nullptr.
This commit fixes the problem by completing the type while trying to
decompose the structured binding.
The ICE happens in real world code, for example, when trying to iterate
a protobuf generated map with a range-based for loop and structure
bindings (because google::protobuf::MapPair is a template and doesn't
support std::tuple_size).
Reported-by: nicholas@nlsun.com
Repository:
rC Clang
https://reviews.llvm.org/D56974
Files:
clang/lib/Sema/SemaDeclCXX.cpp
clang/test/SemaCXX/cxx1z-decomposition.cpp
Index: clang/test/SemaCXX/cxx1z-decomposition.cpp
===
--- clang/test/SemaCXX/cxx1z-decomposition.cpp
+++ clang/test/SemaCXX/cxx1z-decomposition.cpp
@@ -81,4 +81,21 @@
void f() { static auto [a] = *this; } // expected-error {{cannot be declared
'static'}}
};
+namespace instantiate_template {
+
+template
+struct pair {
+ T1 a;
+ T2 b;
+};
+
+const pair &f1();
+
+int f2() {
+ const auto &[a, b] = f1();
+ return a + b;
+}
+
+} // namespace instantiate_template
+
// FIXME: by-value array copies
Index: clang/lib/Sema/SemaDeclCXX.cpp
===
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -1300,6 +1300,10 @@
static bool checkMemberDecomposition(Sema &S, ArrayRef Bindings,
ValueDecl *Src, QualType DecompType,
const CXXRecordDecl *OrigRD) {
+ if (S.RequireCompleteType(Src->getLocation(), DecompType,
+diag::err_incomplete_type))
+return true;
+
CXXCastPath BasePath;
DeclAccessPair BasePair =
findDecomposableBaseClass(S, Src->getLocation(), OrigRD, BasePath);
Index: clang/test/SemaCXX/cxx1z-decomposition.cpp
===
--- clang/test/SemaCXX/cxx1z-decomposition.cpp
+++ clang/test/SemaCXX/cxx1z-decomposition.cpp
@@ -81,4 +81,21 @@
void f() { static auto [a] = *this; } // expected-error {{cannot be declared 'static'}}
};
+namespace instantiate_template {
+
+template
+struct pair {
+ T1 a;
+ T2 b;
+};
+
+const pair &f1();
+
+int f2() {
+ const auto &[a, b] = f1();
+ return a + b;
+}
+
+} // namespace instantiate_template
+
// FIXME: by-value array copies
Index: clang/lib/Sema/SemaDeclCXX.cpp
===
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -1300,6 +1300,10 @@
static bool checkMemberDecomposition(Sema &S, ArrayRef Bindings,
ValueDecl *Src, QualType DecompType,
const CXXRecordDecl *OrigRD) {
+ if (S.RequireCompleteType(Src->getLocation(), DecompType,
+diag::err_incomplete_type))
+return true;
+
CXXCastPath BasePath;
DeclAccessPair BasePair =
findDecomposableBaseClass(S, Src->getLocation(), OrigRD, BasePath);
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