C++11 changed destructors to be noexcept by default; as a result, code
with throwing destructors that works in C++98 immediately calls
terminate in C++11. When testing changing the default for cxx_dialect
to C++11 I noticed that this was causing one of the tests to fail, and
decided to add a warning for a throw-expression in a noexcept function
without an intervening try block. This patch also adds the related
warning to -Wc++11-compat.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 1ec3d94aa682212752ff3e1cef13ac118a71aa78
Author: Jason Merrill <ja...@redhat.com>
Date: Tue May 5 14:01:08 2015 -0500
gcc/c-family/
* c.opt (Wterminate): New.
gcc/cp/
* cp-gimplify.c (cp_genericize_r): Track TRY_BLOCK and
MUST_NOT_THROW_EXPR, warn about a THROW_EXPR directly within a
MUST_NOT_THROW_EXPR.
(cp_genericize_data): Add try_block field.
(cp_genericize_tree): Initialize it.
* except.c (expand_end_catch_block): Set TREE_NO_WARNING on
implicit rethrow.
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 983f4a8..8ef0cea 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -829,6 +829,10 @@ Wsystem-headers
C ObjC C++ ObjC++ Warning
; Documented in common.opt
+Wterminate
+C++ ObjC++ Warning Var(warn_terminate) Init(1)
+Warn if a throw expression will always result in a call to terminate()
+
Wtraditional
C ObjC CPP(cpp_warn_traditional) CppReason(CPP_W_TRADITIONAL) Var(warn_traditional) Init(0) Warning
Warn about features not present in traditional C
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index 70645b5..35749ef 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -905,6 +905,7 @@ struct cp_genericize_data
hash_set<tree> *p_set;
vec<tree> bind_expr_stack;
struct cp_genericize_omp_taskreg *omp_ctx;
+ tree try_block;
};
/* Perform any pre-gimplification lowering of C++ front end trees to
@@ -1193,6 +1194,54 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
wtd->omp_ctx = omp_ctx.outer;
splay_tree_delete (omp_ctx.variables);
}
+ else if (TREE_CODE (stmt) == TRY_BLOCK)
+ {
+ *walk_subtrees = 0;
+ tree try_block = wtd->try_block;
+ wtd->try_block = stmt;
+ cp_walk_tree (&TRY_STMTS (stmt), cp_genericize_r, data, NULL);
+ wtd->try_block = try_block;
+ cp_walk_tree (&TRY_HANDLERS (stmt), cp_genericize_r, data, NULL);
+ }
+ else if (TREE_CODE (stmt) == MUST_NOT_THROW_EXPR)
+ {
+ /* MUST_NOT_THROW_COND might be something else with TM. */
+ if (MUST_NOT_THROW_COND (stmt) == NULL_TREE)
+ {
+ *walk_subtrees = 0;
+ tree try_block = wtd->try_block;
+ wtd->try_block = stmt;
+ cp_walk_tree (&TREE_OPERAND (stmt, 0), cp_genericize_r, data, NULL);
+ wtd->try_block = try_block;
+ }
+ }
+ else if (TREE_CODE (stmt) == THROW_EXPR)
+ {
+ location_t loc = location_of (stmt);
+ if (TREE_NO_WARNING (stmt))
+ /* Never mind. */;
+ else if (wtd->try_block)
+ {
+ if (TREE_CODE (wtd->try_block) == MUST_NOT_THROW_EXPR
+ && warning_at (loc, OPT_Wterminate,
+ "throw will always call terminate()")
+ && cxx_dialect >= cxx11
+ && DECL_DESTRUCTOR_P (current_function_decl))
+ inform (loc, "in C++11 destructors default to noexcept");
+ }
+ else
+ {
+ if (warn_cxx0x_compat && cxx_dialect < cxx11
+ && DECL_DESTRUCTOR_P (current_function_decl)
+ && (TYPE_RAISES_EXCEPTIONS (TREE_TYPE (current_function_decl))
+ == NULL_TREE)
+ && (get_defaulted_eh_spec (current_function_decl)
+ == empty_except_spec))
+ warning_at (loc, OPT_Wc__0x_compat,
+ "in C++11 this throw will terminate because "
+ "destructors default to noexcept");
+ }
+ }
else if (TREE_CODE (stmt) == CONVERT_EXPR)
gcc_assert (!CONVERT_EXPR_VBASE_PATH (stmt));
else if (TREE_CODE (stmt) == FOR_STMT)
@@ -1269,6 +1318,7 @@ cp_genericize_tree (tree* t_p)
wtd.p_set = new hash_set<tree>;
wtd.bind_expr_stack.create (0);
wtd.omp_ctx = NULL;
+ wtd.try_block = NULL_TREE;
cp_walk_tree (t_p, cp_genericize_r, &wtd, NULL);
delete wtd.p_set;
wtd.bind_expr_stack.release ();
diff --git a/gcc/cp/except.c b/gcc/cp/except.c
index 3ff1ce6..614f2e9 100644
--- a/gcc/cp/except.c
+++ b/gcc/cp/except.c
@@ -579,7 +579,11 @@ expand_end_catch_block (void)
if (in_function_try_handler
&& (DECL_CONSTRUCTOR_P (current_function_decl)
|| DECL_DESTRUCTOR_P (current_function_decl)))
- finish_expr_stmt (build_throw (NULL_TREE));
+ {
+ tree rethrow = build_throw (NULL_TREE);
+ TREE_NO_WARNING (rethrow) = true;
+ finish_expr_stmt (rethrow);
+ }
}
tree
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index debd8ed..9c8aa99 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2882,6 +2882,12 @@ Warn when overload resolution chooses a promotion from unsigned or
enumerated type to a signed type, over a conversion to an unsigned type of
the same size. Previous versions of G++ tried to preserve
unsignedness, but the standard mandates the current behavior.
+
+@item -Wno-terminate @r{(C++ and Objective-C++ only)}
+@opindex Wterminate
+@opindex Wno-terminate
+Disable the warning about a throw-expression that will immediately
+result in a call to @code{terminate}.
@end table
@node Objective-C and Objective-C++ Dialect Options
diff --git a/gcc/testsuite/g++.dg/compat/eh/ctor1.h b/gcc/testsuite/g++.dg/compat/eh/ctor1.h
index e83476f..9ad1860 100644
--- a/gcc/testsuite/g++.dg/compat/eh/ctor1.h
+++ b/gcc/testsuite/g++.dg/compat/eh/ctor1.h
@@ -5,6 +5,6 @@ struct Foo
struct Bar
{
- ~Bar ();
+ ~Bar () throw(int);
Foo f;
};
diff --git a/gcc/testsuite/g++.dg/compat/eh/ctor1_y.C b/gcc/testsuite/g++.dg/compat/eh/ctor1_y.C
index 260ab1c..ca1cf38 100644
--- a/gcc/testsuite/g++.dg/compat/eh/ctor1_y.C
+++ b/gcc/testsuite/g++.dg/compat/eh/ctor1_y.C
@@ -7,7 +7,7 @@ Foo::~Foo()
was_f_in_Bar_destroyed=true;
}
-Bar::~Bar()
+Bar::~Bar() throw(int)
{
throw 1;
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept06.C b/gcc/testsuite/g++.dg/cpp0x/noexcept06.C
index 7e1db66..ad9edec 100644
--- a/gcc/testsuite/g++.dg/cpp0x/noexcept06.C
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept06.C
@@ -1,6 +1,7 @@
// Test that checking of a nothrow specification uses the one on the
// definition.
// { dg-do run { target c++11 } }
+// { dg-options "-Wno-terminate" }
#include <exception>
#include <cstdlib>
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept17.C b/gcc/testsuite/g++.dg/cpp0x/noexcept17.C
index b27acef..9ea1623 100644
--- a/gcc/testsuite/g++.dg/cpp0x/noexcept17.C
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept17.C
@@ -1,5 +1,6 @@
// PR c++/50043
// { dg-do compile { target c++11 } }
+// { dg-options "-Wno-terminate" }
struct True1 {};
struct True2 { ~True2(); };
diff --git a/gcc/testsuite/g++.dg/eh/cond4.C b/gcc/testsuite/g++.dg/eh/cond4.C
index a8d1cfb..4d312e4 100644
--- a/gcc/testsuite/g++.dg/eh/cond4.C
+++ b/gcc/testsuite/g++.dg/eh/cond4.C
@@ -12,7 +12,7 @@ void my_terminate ()
struct A {
A(int) { }
- ~A() { throw 1; };
+ ~A() throw(int) { throw 1; };
};
struct B {
B(A) { }
diff --git a/gcc/testsuite/g++.dg/eh/ehopt1.C b/gcc/testsuite/g++.dg/eh/ehopt1.C
index 163d76e..b2fb412 100644
--- a/gcc/testsuite/g++.dg/eh/ehopt1.C
+++ b/gcc/testsuite/g++.dg/eh/ehopt1.C
@@ -15,7 +15,7 @@ class A<int, int>
public:
A(int) { ++count; if (b) throw 1; }
A(const A&) { ++count; if (b) throw 1; }
- ~A() { --count; if (b) throw 1; }
+ ~A() throw(int) { --count; if (b) throw 1; }
};
typedef A<int, int> B;
@@ -26,7 +26,7 @@ class A<void *, void *>
public:
A() { if (b) throw 1; }
A(const B&) { if (b) throw 1; }
- ~A() { if (b) throw 1; }
+ ~A() throw(int) { if (b) throw 1; }
};
typedef A<void *, void *> C;
diff --git a/gcc/testsuite/g++.dg/eh/init-temp2.C b/gcc/testsuite/g++.dg/eh/init-temp2.C
index 6a58dda..9cf8797 100644
--- a/gcc/testsuite/g++.dg/eh/init-temp2.C
+++ b/gcc/testsuite/g++.dg/eh/init-temp2.C
@@ -8,18 +8,18 @@ template <class _Tp> class AutoPtr
public:
explicit AutoPtr(_Tp* __p = 0) : _M_ptr(__p) {}
- ~AutoPtr() { delete _M_ptr; }
+ ~AutoPtr() throw(int) { delete _M_ptr; }
};
struct A
{
A() { }
- ~A() { throw 1.0; }
+ ~A() throw(int) { throw 1; }
};
struct B
{
- virtual ~B();
+ virtual ~B() throw(int);
};
B* f (const A &s) { throw 1; }
diff --git a/gcc/testsuite/g++.dg/tm/noexcept-5.C b/gcc/testsuite/g++.dg/tm/noexcept-5.C
index 4267432..e4d3f53 100644
--- a/gcc/testsuite/g++.dg/tm/noexcept-5.C
+++ b/gcc/testsuite/g++.dg/tm/noexcept-5.C
@@ -1,5 +1,5 @@
// { dg-do compile { target c++11 } }
-// { dg-options "-fgnu-tm -O -fdump-tree-tmmark -fdump-tree-tmlower" }
+// { dg-options "-fgnu-tm -O -fdump-tree-tmmark -fdump-tree-tmlower -Wno-terminate" }
int global;
diff --git a/gcc/testsuite/g++.dg/torture/pr49394.C b/gcc/testsuite/g++.dg/torture/pr49394.C
index 67d521f..e471885 100644
--- a/gcc/testsuite/g++.dg/torture/pr49394.C
+++ b/gcc/testsuite/g++.dg/torture/pr49394.C
@@ -4,7 +4,7 @@
struct Mutex
{
bool locked;
- ~Mutex ()
+ ~Mutex () throw(int)
{
if (locked)
throw 0;
diff --git a/gcc/testsuite/g++.dg/warn/Wterminate1.C b/gcc/testsuite/g++.dg/warn/Wterminate1.C
new file mode 100644
index 0000000..affb48d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wterminate1.C
@@ -0,0 +1,20 @@
+// In C++98 mode this gets a -Wc++11-compat warning, in C++11 mode a
+// -Wterminate warning.
+
+// { dg-options "-Wall" }
+
+struct A
+{
+ ~A()
+ {
+ throw 1; // { dg-warning "terminate" }
+ }
+};
+
+int main()
+{
+ try { A a; }
+ catch (...) {}
+}
+
+
diff --git a/gcc/testsuite/g++.old-deja/g++.mike/eh25.C b/gcc/testsuite/g++.old-deja/g++.mike/eh25.C
index fb492f7..f3728cf 100644
--- a/gcc/testsuite/g++.old-deja/g++.mike/eh25.C
+++ b/gcc/testsuite/g++.old-deja/g++.mike/eh25.C
@@ -10,7 +10,7 @@ void my_terminate() {
struct A {
A() { }
- ~A() {
+ ~A() throw(int) {
std::set_terminate (my_terminate);
throw 1; // This throws from EH dtor, should call my_terminate
}
diff --git a/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc b/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc
index 4219782a..6d99c27 100644
--- a/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc
+++ b/libstdc++-v3/testsuite/30_threads/lock_guard/cons/1.cc
@@ -27,7 +27,7 @@ struct Mutex
{
Mutex() : locked(false) { }
- ~Mutex()
+ ~Mutex() throw(int)
{
if (locked)
throw 0;
diff --git a/libstdc++-v3/testsuite/util/replacement_memory_operators.h b/libstdc++-v3/testsuite/util/replacement_memory_operators.h
index 0bfa3fc..06d955a 100644
--- a/libstdc++-v3/testsuite/util/replacement_memory_operators.h
+++ b/libstdc++-v3/testsuite/util/replacement_memory_operators.h
@@ -32,7 +32,7 @@ namespace __gnu_test
counter() : _M_count(0), _M_throw(true) { }
- ~counter()
+ ~counter() throw (counter_error)
{
if (_M_throw && _M_count != 0)
throw counter_error();
