The atom_cache in normalize_atom relies on the assumption that two equivalent (templated) trees (in the sense of cp_tree_equal) must use the same template parameters (according to find_template_parameters).
This assumption unfortunately doesn't always hold for TARGET_EXPRs, because cp_tree_equal ignores an artificial target of a TARGET_EXPR, but find_template_parameters walks this target (and its DECL_CONTEXT). Hence two TARGET_EXPRs built by force_target_expr with the same initializer but under different settings of current_function_decl may compare equal according to cp_tree_equal, but find_template_parameters returns a different set of template parameters for them. This breaks the below testcase because during normalization we build two such TARGET_EXPRs (one under current_function_decl=f and another under =g), and then use the same ATOMIC_CONSTR for the two corresponding atoms, leading to a crash during satisfaction of g's associated constraints. This patch works around this assumption violation by removing the source of these templated TARGET_EXPRs. The relevant call to get_target_expr was added in r9-6043, but it seems it's no longer necessary (according to https://gcc.gnu.org/pipermail/gcc-patches/2019-February/517323.html, the call was added in order to avoid regressing on initlist109.C at the time). Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for trunk? gcc/cp/ChangeLog: * semantics.c (finish_compound_literal): Don't wrap the original compound literal in a TARGET_EXPR when inside a template. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/concepts-decltype3.C: New test. --- gcc/cp/semantics.c | 7 +------ gcc/testsuite/g++.dg/cpp2a/concepts-decltype3.C | 15 +++++++++++++++ 2 files changed, 16 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-decltype3.C diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 33d715edaec..172286922e7 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -3006,12 +3006,7 @@ finish_compound_literal (tree type, tree compound_literal, /* If we're in a template, return the original compound literal. */ if (orig_cl) - { - if (!VECTOR_TYPE_P (type)) - return get_target_expr_sfinae (orig_cl, complain); - else - return orig_cl; - } + return orig_cl; if (TREE_CODE (compound_literal) == CONSTRUCTOR) { diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-decltype3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-decltype3.C new file mode 100644 index 00000000000..837855ce8ac --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-decltype3.C @@ -0,0 +1,15 @@ +// { dg-do compile { target c++20 } } + +template <class T> concept C = requires(T t) { t; }; + +template <class T> using A = decltype((T{}, int{})); + +template <class T> concept D = C<A<T>>; + +template <class T, class U> void f() requires D<T>; +template <class T> void g() requires D<T>; + +void h() { + f<int, int>(); + g<int>(); +} -- 2.29.2.260.ge31aba42fb
