[pushed] testsuite: update mangling

[Jason Merrill]

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

-- 8< --
Since r14-6064-gc3f281a0c1ca50 this test was checking for the wrong
mangling, but it still passed on targets that support ABI compatibility
aliases.  Let's avoid generating those aliases when checking mangling.

gcc/ChangeLog:

        * common.opt: Add comment.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp2a/concepts-explicit-inst1.C: Specify ABI v18.
        * g++.dg/cpp2a/concepts-explicit-inst1a.C: New test.
---
 gcc/common.opt                                |  1 +
 .../g++.dg/cpp2a/concepts-explicit-inst1.C    |  1 +
 .../g++.dg/cpp2a/concepts-explicit-inst1a.C   | 24 +++++++++++++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1a.C

diff --git a/gcc/common.opt b/gcc/common.opt
index 5eb5ecff04b..d263a959df3 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1020,6 +1020,7 @@ Driver Undocumented
 ;
 ; 19: Emits ABI tags if needed in structured binding mangled names.
 ;     Ignores cv-quals on [[no_unique_object]] members.
+;     Mangles constraints on function templates.
 ;     Default in G++ 14.
 ;
 ; Additional positive integers will be assigned as new versions of
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1.C 
b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1.C
index 5cbf64a8cd3..b66e919e880 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1.C
@@ -1,4 +1,5 @@
 // { dg-do compile { target c++20 } }
+// { dg-additional-options "-fabi-version=18 -fabi-compat-version=18" }
 // { dg-final { scan-assembler "_Z1gI1XEvT_" } }
 // { dg-final { scan-assembler "_Z1gI1YEvT_" } }
 // { dg-final { scan-assembler "_Z1gIiEvT_" } }
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1a.C 
b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1a.C
new file mode 100644
index 00000000000..feb31f9e24c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-explicit-inst1a.C
@@ -0,0 +1,24 @@
+// { dg-do compile { target c++20 } }
+// { dg-additional-options "-fabi-version=0 -fabi-compat-version=0" }
+// { dg-final { scan-assembler "_Z1gITk1C1YEvT_" } }
+// { dg-final { scan-assembler "_Z1gITk1D1XEvT_" } }
+// { dg-final { scan-assembler "_Z1gIiEvT_" } }
+
+template<typename T>
+  concept C = __is_class(T);
+
+template<typename T>
+  concept D = C<T> && __is_empty(T);
+
+struct X { };
+struct Y { int n; };
+
+template<typename T> void g(T) { } // #1
+template<C T> void g(T) { } // #2
+template<D T> void g(T) { } // #3
+
+template void g(int); // Instantiate #1
+template void g(X); // Instantitae #3
+template void g(Y); // Instantiate #2
+
+int main() { }

base-commit: 889341a897d3d2e9fb09de1a1c5e764a2c03424f
prerequisite-patch-id: 6f3182b395d62bae9a7b1930edc21d52611c328c
-- 
2.39.3