c++: ICE when mangling operator name [PR98545]

r11-6301 added some asserts in mangle.c, and now we trip over one of
them.  In particular, it's the one asserting that we didn't get
IDENTIFIER_ANY_OP_P when mangling an expression with a dependent name.

As this testcase shows, it's possible to get that, so turn the assert
into an if and write "on".  That changes the mangling in the following
way:

With this patch:

$ c++filt _ZN1i1hIJ1adS1_EEEDTcldtdefpTonclspcvT__EEEDpS2_
decltype (((*this).(operator()))((a)(), (double)(), (a)())) i::h<a, double, a>(a, double, a)

G++10:
$ c++filt _ZN1i1hIJ1adS1_EEEDTcldtdefpTclspcvT__EEEDpS2_
decltype (((*this).(operator()))((a)(), (double)(), (a)())) i::h<a, double, a>(a, double, a)

clang++/icc:
$ c++filt _ZN1i1hIJ1adS1_EEEDTclonclspcvT__EEEDpS2_
decltype ((operator())((a)(), (double)(), (a)())) i::h<a, double, a>(a, double, a)

This is now tracked in PR98756.

gcc/cp/ChangeLog:

	PR c++/98545
	* mangle.c (write_member_name): Emit abi_warn_or_compat_version_crosses
	warnings regardless of abi_version_at_least.
	(write_expression): When the expression is a dependent name
	and an operator name, write "on" before writing its name.

gcc/ChangeLog:

	PR c++/98545
	* doc/invoke.texi: Update C++ ABI Version 15 description.

gcc/testsuite/ChangeLog:

	PR c++/98545
	* g++.dg/abi/mangle76.C: New test.

1 files changed, 40 insertions, 0 deletions

diff --git a/gcc/testsuite/g++.dg/abi/mangle76.C b/gcc/testsuite/g++.dg/abi/mangle76.C
new file mode 100644
index 0000000..fe326e6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/mangle76.C
@@ -0,0 +1,40 @@
+// PR c++/98545
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wabi=14" }
+
+class a {
+public:
+  a();
+  template <typename b> a(b);
+};
+template <class = double> using c = a;
+class f {
+protected:
+  template <class d, class e> void operator()(d, double, e);
+};
+class i : f {
+public:
+  template <class... g>
+  [[gnu::used]] auto h(g...) -> decltype(operator()(g()...)) {} // { dg-warning "mangled name" }
+// { dg-final { scan-assembler "_ZN1i1hIJ1adS1_EEEDTcldtdefpTonclspcvT__EEEDpS2_" } }
+};
+template <class> class C {
+public:
+  template <class j> C(j);
+  i k() const;
+  int operator()() {
+    int l = 10;
+    c<> m, n;
+    operator()(m, l, n);
+    return 0;
+  }
+  int operator()(c<> &, c<> const &, c<> const &) const;
+  template <class d, class e> void k(d m, double gamma, e o) const {
+    k().h(m, gamma, o);
+  }
+};
+template <class r> int C<r>::operator()(c<> &, c<> const &, c<> const &) const {
+  [&](c<> m, double gamma, c<> o) { k(m, gamma, o); };
+  return 0;
+}
+c<> p = C<double>(p)();