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

Message ID 20220328133255.2582831-1-jason@redhat.com
State New
Headers show
Series [pushed] c++: mangling union{1} in template [PR104847] | expand

Commit Message

Jason Merrill March 28, 2022, 1:32 p.m. UTC 
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.

Tested x86_64-pc-linux-gnu, applying to trunk.

	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.
---
 gcc/cp/mangle.cc                         |  2 +-
 gcc/testsuite/g++.dg/abi/mangle-union1.C | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/abi/mangle-union1.C


base-commit: bc86a86a4f2c057bc0e0be94dcbb8c128ae7f717
prerequisite-patch-id: 09e711b54e7911a4a04bd7808abc1b73ae4482ba
prerequisite-patch-id: 566cf0772894d0c6a842b2e0ca62eb1d5ae8ad33
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Patch

diff --git a/gcc/cp/mangle.cc b/gcc/cp/mangle.cc
index dbcec0a55bc..eb53e0ebeb4 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 00000000000..f2ee4576adf
--- /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_" } }