test: Add a test for catching pointers by reference

This test should make sure that
https://github.com/mstorsjo/llvm-mingw/issues/522 doesn't
regress again.

test/Makefile

@@ -70,7 +70,7 @@ TESTS_C_NO_BUILTIN = crt-test
 TESTS_C_ANSI_STDIO = crt-test
 TESTS_C_AS_CPP = crt-test
 TESTS_CPP = hello-cpp global-terminate tlstest-main longjmp-cleanup
-TESTS_CPP_EXCEPTIONS = hello-exception exception-locale exception-reduced
+TESTS_CPP_EXCEPTIONS = hello-exception exception-locale exception-reduced exception-catch-ptr-ref
 TESTS_CPP_STATIC = hello-exception
 TESTS_CPP_DLL = tlstest-lib throwcatch-lib
 TESTS_CPP_LINK_DLL = throwcatch-main

test/exception-catch-ptr-ref.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2025 Martin Storsjo
+ *
+ * This file is part of llvm-mingw.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+int main(int argc, char* argv[]) {
+    try {
+        const char *e = "EX";
+        printf("throwing e %p &e %p\n", e, &e);
+        throw e;
+    } catch (const char* &e) {
+        printf("caught e %p &e %p\n", e, &e);
+        printf("e=%s\n", e);
+        if (strcmp(e, "EX")) {
+            printf("Incorrect string pointer reference caught!\n");
+            return 1;
+        }
+    }
+    return 0;
+}