[PATCH v2 3/9] gdb/testsuite: account for clang's nested destructor calls on gdb.cp/mb-ctor.exp

[Bruno Larsen <blarsen@redhat.com>]

When compiling virtual classes's destructors, two versions are compiled,
one with a single parameter (this) and the other with 2 parameters (this
and vtt).

GCC's compilation makes it so either the version with 1
parameter or the one with 2 parameters is called, depending on whether
the destructor is being called by the class itself or by an inherited
class. On the test gdb.cp/mb-ctor.exp, this means that the breakpoint
set at the destructor will be hit 4 times.

Clang, on the other hand, makes the single-parameter version call the 2
parameter version, probably in an attempt to reduce the size of the
resulting executable. This means that the gdb.cp/mb-ctor.exp will hit 6
breakpoints before finishing, and is the reason why this test was
failing. To make this test stop failing, a compiler check is added and
another "continue" instruction is issued to account for this difference.
---
 gdb/testsuite/gdb.cp/mb-ctor.exp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/gdb/testsuite/gdb.cp/mb-ctor.exp b/gdb/testsuite/gdb.cp/mb-ctor.exp
index 5a3c0a4a90f..05dbf507e90 100644
--- a/gdb/testsuite/gdb.cp/mb-ctor.exp
+++ b/gdb/testsuite/gdb.cp/mb-ctor.exp
@@ -25,6 +25,12 @@ if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
     return -1
 }
 
+if {[test_compiler_info {clang-*-*} c++]} {
+    set using_clang true
+} else {
+    set using_clang false
+}
+
 if ![runto_main] then {
     perror "couldn't run to breakpoint"
     return
@@ -71,6 +77,13 @@ gdb_continue_to_breakpoint "set breakpoint here, second dynamic time"\
 
 gdb_test "continue" ".*Breakpoint.*~Derived.*" "Run to dynamic destructor v1"
 
+# Clang makes Derived::~Derived(this) call Derived::~Derives(this, vtt)
+# whereas gcc puts all the logic necessary on both functions.
+if {$using_clang} {
+    gdb_test "continue" ".*Breakpoint.*~Derived.*"\
+	"clang's nested dynamic destructor call"
+}
+
 gdb_test "continue" ".*Breakpoint.*~Derived.*" "Run to dynamic destructor v2"
 
 gdb_test "continue" \
@@ -81,6 +94,11 @@ gdb_test "continue" \
     ".*Breakpoint.*~Derived.*" \
     "run to breakpoint 3 v2"
 
+if {$using_clang} {
+    gdb_test "continue" ".*Breakpoint.*~Derived.*"\
+	"clang's nested destructor call"
+}
+
 gdb_test "continue" \
     ".*exited normally.*" \
     "run to exit"
-- 
2.37.3