[PR88534] accept VAR_DECL in class literal template parms

P0732R2 / C++ 2a introduce class literals as template parameters.  The
front-end uses VAR_DECLs constructed from such literals to bind the
template PARM_DECLs, but dwarf2out.c used to reject such VAR_DECLs.

Taking DECL_INITIAL from such VAR_DECLs enables the generation of
DW_AT_const_value for them, at least when the class literal can
actually be represented as such.


for  gcc/ChangeLog

	PR c++/88534
	PR c++/88537
	* dwarf2out.c (generic_parameter_die): Follow DECL_INITIAL of
	VAR_DECL args.

for  gcc/testsuite/ChangeLog

	PR c++/88534
	PR c++/88537
	* g++.dg/cpp2a/pr88534.C: New.
	* g++.dg/cpp2a/pr88537.C: New.

From-SVN: r269709

5 files changed, 102 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d7a4f38..dfec589 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2019-03-15  Alexandre Oliva <aoliva@redhat.com>
+
+	PR c++/88534
+	PR c++/88537
+	* dwarf2out.c (generic_parameter_die): Follow DECL_INITIAL of
+	VAR_DECL args.
+
 2019-03-15  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/89709
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index d9cefd3..251fff7 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -13603,6 +13603,13 @@ generic_parameter_die (tree parm, tree arg,
   dw_die_ref tmpl_die = NULL;
   const char *name = NULL;
 
+  /* C++2a accepts class literals as template parameters, and var
+     decls with initializers represent them.  The VAR_DECLs would be
+     rejected, but we can take the DECL_INITIAL constructor and
+     attempt to expand it.  */
+  if (arg && VAR_P (arg))
+    arg = DECL_INITIAL (arg);
+
   if (!parm || !DECL_NAME (parm) || !arg)
     return NULL;
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 285dc51..139e45a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2019-03-15  Alexandre Oliva <aoliva@redhat.com>
+
+	PR c++/88534
+	PR c++/88537
+	* g++.dg/cpp2a/pr88534.C: New.
+	* g++.dg/cpp2a/pr88537.C: New.
+
 2019-03-15  Robin Dapp  <rdapp@linux.ibm.com>
 
 	* gcc.target/s390/target-attribute/tattr-1.c (htm0): -mhtm -> '-mhtm'.
diff --git a/gcc/testsuite/g++.dg/cpp2a/pr88534.C b/gcc/testsuite/g++.dg/cpp2a/pr88534.C
new file mode 100644
index 0000000..54faf38
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/pr88534.C
@@ -0,0 +1,65 @@
+// { dg-do compile { target c++2a } }
+// { dg-options "-g" }
+
+typedef __SIZE_TYPE__ size_t;
+
+namespace std
+{
+
+template <typename T, T... I>
+struct integer_sequence
+{
+  typedef T value_type;
+  static constexpr size_t size () noexcept { return sizeof...(I); }
+};
+
+template <typename T, T N>
+using make_integer_sequence = integer_sequence<T, __integer_pack (N)...>;
+
+template <size_t... I>
+using index_sequence = integer_sequence<size_t, I...>;
+
+template <size_t N>
+using make_index_sequence = make_integer_sequence<size_t, N>;
+}
+
+template <typename T, size_t N> struct S
+{
+  T content[N];
+  using char_type = T;
+  template <size_t... I>
+  constexpr S (const T (&input)[N], std::index_sequence<I...>) noexcept : content{input[I]...} { }
+  constexpr S (const T (&input)[N]) noexcept : S (input, std::make_index_sequence<N> ()) { }
+  constexpr size_t size () const noexcept
+  {
+    if (content[N - 1] == '\0')
+      return N - 1;
+    else
+      return N;
+  }
+  constexpr T operator[] (size_t i) const noexcept
+  {
+    return content[i];
+  }
+  constexpr const T *begin () const noexcept
+  {
+    return content;
+  }
+  constexpr const T *end () const noexcept
+  {
+    return content + size ();
+  }
+};
+
+template <typename T, size_t N> S (const T (&)[N]) -> S<T, N>;
+
+template <S S>
+struct F
+{
+};
+
+auto
+foo ()
+{
+  F<"test"> f;
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/pr88537.C b/gcc/testsuite/g++.dg/cpp2a/pr88537.C
new file mode 100644
index 0000000..d558d45
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/pr88537.C
@@ -0,0 +1,16 @@
+// { dg-do compile { target c++2a } }
+// { dg-options "-g" }
+
+struct pair {
+	unsigned a;
+	unsigned b;
+	constexpr pair(unsigned _a, unsigned _b) noexcept: a{_a}, b{_b} { }
+};
+
+template <pair p> void fnc() {
+	
+}
+
+void f() {
+    fnc<pair(10,20)>();
+}