This is a crash where a FIX_TRUNC_EXPR gets into tsubst_copy_and_build where it hits gcc_unreachable ().
The history of tsubst_copy_and_build/FIX_TRUNC_EXPR is such that it was introduced in r181478, but it did the wrong thing, whereupon it was turned into gcc_unreachable () in r258821 (see this thread: <https://gcc.gnu.org/pipermail/gcc-patches/2018-March/495853.html>). In a template, we should never create a FIX_TRUNC_EXPR (that's what conv_unsafe_in_template_p is for). But in this test we are NOT in a template when we call digest_nsdmi_init which ends up calling convert_like, converting 1.0e+0 to int, so convert_to_integer_1 gives us a FIX_TRUNC_EXPR. But then when we get to parsing f's parameters, we are in a template when processing decltype(Helpers{}), and since r268321, when the compound literal isn't instantiation-dependent and the type isn't type-dependent, finish_compound_literal falls back to the normal processing, so it calls digest_init, which does fold_non_dependent_init and since the FIX_TRUNC_EXPR isn't dependent, we instantiate and therefore crash in tsubst_copy_and_build. Either I can tweak p_c_e to say that a FIX_TRUNC_EXPR in a template is not potentially constant, or I can just remove the whole F_T_E case, since: a) we could not have created an IMPLICIT_CONV_EXPR here, and b) similar code, FLOAT_EXPR, is not handled here, either. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/11? PR c++/102990 gcc/cp/ChangeLog: * pt.cc (tsubst_copy_and_build) <case FIX_TRUNC_EXPR>: Remove. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/nsdmi-template22.C: New test. * g++.dg/cpp0x/nsdmi-template23.C: New test. --- gcc/cp/pt.cc | 4 ---- gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C | 13 +++++++++++++ gcc/testsuite/g++.dg/cpp0x/nsdmi-template23.C | 13 +++++++++++++ 3 files changed, 26 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/nsdmi-template23.C diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 715eea27577..a3becc19290 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -20184,10 +20184,6 @@ tsubst_copy_and_build (tree t, templated_operator_saved_lookups (t), complain|decltype_flag)); - case FIX_TRUNC_EXPR: - /* convert_like should have created an IMPLICIT_CONV_EXPR. */ - gcc_unreachable (); - case ADDR_EXPR: op1 = TREE_OPERAND (t, 0); if (TREE_CODE (op1) == LABEL_DECL) diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C new file mode 100644 index 00000000000..4ed2501035c --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template22.C @@ -0,0 +1,13 @@ +// PR c++/102990 +// { dg-do compile { target c++11 } } + +struct knob_t { + /* Let's create a FIX_TRUNC_EXPR. */ + int value = 1.0; +}; + +struct Helpers { + knob_t inputs; +}; + +template<class> void f(decltype(Helpers{})); diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template23.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template23.C new file mode 100644 index 00000000000..240cab4347a --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template23.C @@ -0,0 +1,13 @@ +// PR c++/102990 +// { dg-do compile { target c++11 } } + +struct knob_t { + /* Let's create a FLOAT_EXPR. */ + double value = 1UL; +}; + +struct Helpers { + knob_t inputs; +}; + +template<class> void f(decltype(Helpers{})); base-commit: 5d2233f4033dfa37ad88dc2eab138524fe64242e -- 2.35.1
