From: Jason Merrill <jason@redhat.com>
Date: Sun, 27 Mar 2022 00:10:19 +0000 (-0400)
Subject: c++: mangling union{1} in template [PR104847]
X-Git-Tag: basepoints/gcc-13~464
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71e1db540c01a13b01fae054c92878a79252b471;p=thirdparty%2Fgcc.git

c++: mangling union{1} in template [PR104847]

My implementation of union non-type template arguments in r11-2016 broke
braced casts of union type, because they are still in syntactic (undigested)
form.

	PR c++/104847

gcc/cp/ChangeLog:

	* mangle.cc (write_expression): Don't write a union designator when
	undigested.

gcc/testsuite/ChangeLog:

	* g++.dg/abi/mangle-union1.C: New test.
---

diff --git a/gcc/cp/mangle.cc b/gcc/cp/mangle.cc
index dbcec0a55bc3..eb53e0ebeb43 100644
--- a/gcc/cp/mangle.cc
+++ b/gcc/cp/mangle.cc
@@ -3363,7 +3363,7 @@ write_expression (tree expr)
 		  {
 		    if (i > last_nonzero)
 		      break;
-		    if (TREE_CODE (etype) == UNION_TYPE)
+		    if (!undigested && TREE_CODE (etype) == UNION_TYPE)
 		      {
 			/* Express the active member as a designator.  */
 			write_string ("di");
diff --git a/gcc/testsuite/g++.dg/abi/mangle-union1.C b/gcc/testsuite/g++.dg/abi/mangle-union1.C
new file mode 100644
index 000000000000..f2ee4576adfa
--- /dev/null
+++ b/gcc/testsuite/g++.dg/abi/mangle-union1.C
@@ -0,0 +1,10 @@
+// PR c++/104847
+// { dg-do compile { target c++11 } }
+
+struct S { int i; };
+union U { S k; };
+template <class T, class... Ts> T sink(T&&, Ts&&...);
+template <class T>
+decltype(sink(U{1},T())) f(T) { return U{1}; }
+int main() { f(3); }
+// { dg-final { scan-assembler "_Z1fIiEDTcl4sinktl1ULi1EEcvT__EEES1_" } }