https://gcc.gnu.org/g:1e9e8c36d8f35c3256d78d4aa556f0ef4fba998e
commit r15-10657-g1e9e8c36d8f35c3256d78d4aa556f0ef4fba998e Author: Jason Merrill <[email protected]> Date: Fri Jan 9 15:02:53 2026 +0800 c++: implicit 'this' in generic lambda [PR122048] Here template substitution was replacing a reference to the 'this' of X::f with the implicit closure parameter of the operator(), which is wrong. The closure parameter is never a suitable replacement for a 'this' parameter. PR c++/122048 gcc/cp/ChangeLog: * pt.cc (tsubst_expr): Don't use a lambda current_class_ptr. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/lambda-generic-this6.C: New test. (cherry picked from commit 90ad957406104f9cc04365f6b071521a7c013dda) Diff: --- gcc/cp/pt.cc | 3 ++- gcc/testsuite/g++.dg/cpp1y/lambda-generic-this6.C | 8 ++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 2c3cb2e7b8e1..e8755a2637d8 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -22023,7 +22023,8 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl) if (r == NULL_TREE && TREE_CODE (t) == PARM_DECL) { /* We get here for a use of 'this' in an NSDMI. */ - if (DECL_NAME (t) == this_identifier && current_class_ptr) + if (DECL_NAME (t) == this_identifier && current_class_ptr + && !LAMBDA_TYPE_P (TREE_TYPE (TREE_TYPE (current_class_ptr)))) RETURN (current_class_ptr); /* This can happen for a parameter name used later in a function diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this6.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this6.C new file mode 100644 index 000000000000..8bbff1d9fd25 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-this6.C @@ -0,0 +1,8 @@ +// PR c++/122048 +// { dg-do compile { target c++14 } } + +class X { + void f(); + int i; +}; +void X::f() {[&](auto) {sizeof i;}(1);}
