[Bug c++/102990] [9/10/11 Regression] ICE in tsubst_copy_and_build with NSDMI and double to int conversion

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990

--- Comment #14 from CVS Commits  ---
The releases/gcc-11 branch has been updated by Marek Polacek
:

https://gcc.gnu.org/g:6ba2a7e7474135b717c344030b114ffd6ad8ed7a

commit r11-9711-g6ba2a7e7474135b717c344030b114ffd6ad8ed7a
Author: Marek Polacek 
Date:   Tue Mar 22 18:42:27 2022 -0400

c++: FIX_TRUNC_EXPR in tsubst [PR102990]

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:
).

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.

The fateful call to fold_non_dependent_init comes from massage_init_elt,
We shouldn't be calling f_n_d_i on the result of get_nsdmi.  This we can
avoid by eschewing calling f_n_d_i on CONSTRUCTORs; their elements have
already been folded.

PR c++/102990

gcc/cp/ChangeLog:

* typeck2.c (massage_init_elt): Avoid folding CONSTRUCTORs.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/nsdmi-template22.C: New test.
* g++.dg/cpp0x/nsdmi-template23.C: New test.

(cherry picked from commit f0530882d99abc410bb080051aa04e5cea848f18)

[Bug c++/102990] [9/10/11 Regression] ICE in tsubst_copy_and_build with NSDMI and double to int conversion

[mpolacek at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990

--- Comment #13 from Marek Polacek  ---
I was planning to backport the fix to 11, yes.

[Bug c++/102990] [9/10/11 Regression] ICE in tsubst_copy_and_build with NSDMI and double to int conversion

[jeanmichael.celerier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990

--- Comment #12 from Jean-Michaël Celerier  ---
In any case many thanks for fixing this !

[Bug c++/102990] [9/10/11 Regression] ICE in tsubst_copy_and_build with NSDMI and double to int conversion

[jeanmichael.celerier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990

--- Comment #11 from Jean-Michaël Celerier  ---
Do you know if the patch will be applied to the 10.x / 11.x branches ?

[Bug c++/102990] [9/10/11 Regression] ICE in tsubst_copy_and_build with NSDMI and double to int conversion

[mpolacek at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102990

Marek Polacek  changed:

   What|Removed |Added

Summary|[9/10/11/12 Regression] ICE |[9/10/11 Regression] ICE in
   |in tsubst_copy_and_build|tsubst_copy_and_build with
   |with NSDMI and double to|NSDMI and double to int
   |int conversion  |conversion

--- Comment #10 from Marek Polacek  ---
Fixed on trunk so far.