DebugInfo: Don't simplify any template referencing a lambda

Lambda names aren't entirely canonical (as demonstrated by the
cross-project-test added here) at the moment (we should fix that for a
bunch of reasons) - even if the template referencing them is
non-simplified, other names referencing /that/ template can't be
simplified either because type units might cause a different template to
be picked up that would conflict with the expected name.

(other than for roundtripping precision, it'd be OK to simplify types
that reference types that reference lambdas - but best be consistent
between the roundtrip/verify mode and the actual simplified template
names mode)

2 files changed, 41 insertions, 0 deletions

diff --git a/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names.cpp b/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names.cpp
index 61ac76db832c..d608039959df 100644
--- a/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names.cpp
+++ b/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names.cpp
@@ -216,6 +216,7 @@ int main() {
   f1<t3<t3<int>>>();
   f1<decltype(L)>();
   t3<decltype(L)> v1;
+  f1<t3<t3<decltype(L)>>>();
   f1<int(float)>();
   f1<void(...)>();
   f1<void(int, ...)>();
diff --git a/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names_noncanonical_type_units.cpp b/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names_noncanonical_type_units.cpp
new file mode 100644
index 000000000000..65c6bba6746f
--- /dev/null
+++ b/cross-project-tests/debuginfo-tests/clang_llvm_roundtrip/simplified_template_names_noncanonical_type_units.cpp
@@ -0,0 +1,40 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: mkdir %t/incl
+// RUN: mv %t/header.h %t/incl/header.h
+// RUN: cd %t
+// RUN: %clang %target_itanium_abi_host_triple -g -o %t/a.out \
+// RUN:   -Xclang -gsimple-template-names=mangled \
+// RUN:   -Xclang -debug-forward-template-params \
+// RUN:   -std=c++20 -fdebug-types-section -I incl a.cpp b.cpp
+// RUN: llvm-dwarfdump --verify %t/a.out
+
+//--- header.h
+template <typename T> struct t1 {};
+inline auto f1() {
+  auto T = [] {};
+  t1<decltype(T)> v;
+  return v;
+}
+inline auto f2() {
+  struct {
+  } T;
+  t1<decltype(T)> v;
+  return v;
+}
+void a();
+//--- a.cpp
+#include "incl/header.h"
+template <typename T> void ft() {}
+void a() {
+  ft<decltype(f1())>();
+  ft<decltype(f2())>();
+}
+//--- b.cpp
+#include "header.h"
+template <typename T> void ft() {}
+int main() {
+  a();
+  ft<decltype(f1())>();
+  ft<decltype(f2())>();
+}