Re: [PATCH] c++: NSDMI instantiation during overload resolution [PR110468]

[Jason Merrill via Gcc-patches]

On 6/29/23 11:22, Patrick Palka wrote:

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/13/12?


OK.


-- >8 --

Here we find ourselves instantiating the NSDMI for A<1>::m when
computing argument conversions during overload resolution, and
thus tf_conv is set.  This causes mark_used for the constructor
used in the NSDMI to exit early and not instantiate its noexcept-spec,
leading to an ICE from nothrow_spec_p.

This patch fixes this by clearing any unusual tsubst flags during
instantiation of an NSDMI, since the result should be independent of
the context that requires the instantiation.

PR c++/110468

gcc/cp/ChangeLog:

* init.cc (maybe_instantiate_nsdmi_init): Mask out all
tsubst flags except for tf_warning_or_error.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/noexcept79.C: New test.
---
  gcc/cp/init.cc  |  4 
  gcc/testsuite/g++.dg/cpp0x/noexcept79.C | 18 ++
  2 files changed, 22 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept79.C

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index af6e30f511e..f01a11c5299 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -579,6 +579,10 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t 
complain)
/* tsubst_decl uses void_node to indicate an uninstantiated DMI.  */
if (init == void_node)
  {
+  /* The result of NSDMI instantiation should be independent of
+the tsubst flags we're given.  */
+  complain &= tf_warning_or_error;
+
init = DECL_INITIAL (DECL_TI_TEMPLATE (member));
location_t expr_loc
= cp_expr_loc_or_loc (init, DECL_SOURCE_LOCATION (member));
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept79.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept79.C
new file mode 100644
index 000..d1f54d14431
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept79.C
@@ -0,0 +1,18 @@
+// PR c++/110468
+// { dg-do compile { target c++11 } }
+
+template
+struct variant {
+  variant() noexcept(T > 0);
+};
+
+template
+struct A {
+  variant m = {};
+};
+
+struct B {
+  B(A<1>);
+};
+
+B b = {{}};

[PATCH] c++: NSDMI instantiation during overload resolution [PR110468]

[Patrick Palka via Gcc-patches]

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk/13/12?

-- >8 --

Here we find ourselves instantiating the NSDMI for A<1>::m when
computing argument conversions during overload resolution, and
thus tf_conv is set.  This causes mark_used for the constructor
used in the NSDMI to exit early and not instantiate its noexcept-spec,
leading to an ICE from nothrow_spec_p.

This patch fixes this by clearing any unusual tsubst flags during
instantiation of an NSDMI, since the result should be independent of
the context that requires the instantiation.

PR c++/110468

gcc/cp/ChangeLog:

* init.cc (maybe_instantiate_nsdmi_init): Mask out all
tsubst flags except for tf_warning_or_error.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/noexcept79.C: New test.
---
 gcc/cp/init.cc  |  4 
 gcc/testsuite/g++.dg/cpp0x/noexcept79.C | 18 ++
 2 files changed, 22 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept79.C

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index af6e30f511e..f01a11c5299 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -579,6 +579,10 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t 
complain)
   /* tsubst_decl uses void_node to indicate an uninstantiated DMI.  */
   if (init == void_node)
 {
+  /* The result of NSDMI instantiation should be independent of
+the tsubst flags we're given.  */
+  complain &= tf_warning_or_error;
+
   init = DECL_INITIAL (DECL_TI_TEMPLATE (member));
   location_t expr_loc
= cp_expr_loc_or_loc (init, DECL_SOURCE_LOCATION (member));
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept79.C 
b/gcc/testsuite/g++.dg/cpp0x/noexcept79.C
new file mode 100644
index 000..d1f54d14431
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept79.C
@@ -0,0 +1,18 @@
+// PR c++/110468
+// { dg-do compile { target c++11 } }
+
+template
+struct variant {
+  variant() noexcept(T > 0);
+};
+
+template
+struct A {
+  variant m = {};
+};
+
+struct B {
+  B(A<1>);
+};
+
+B b = {{}};
-- 
2.41.0.199.ga9e066fa63