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Re: C++ PATCH for c++/85363, wrong-code with throwing list-initializer


On Wed, May 16, 2018 at 11:35:56AM -0400, Jason Merrill wrote:
> On Wed, May 16, 2018 at 11:15 AM, Marek Polacek <polacek@redhat.com> wrote:
> > This PR has been on my mind for quite some time but I've not found a solution
> > that I'd like.  Maybe one of you can think of something better.
> >
> > The problem in this test is that in C++11, .eh optimizes out the catch,
> > so the exception is never caught.  That is because lower_catch doesn't
> > think that the region may throw (eh_region_may_contain_throw).  That's
> > so because P::P () is marked as TREE_NOTHROW, which is wrong, because
> > it calls X::X() which calls init() with throw.  TREE_NOTHROW is set in
> > finish_function:
> >
> >   /* If this function can't throw any exceptions, remember that.  */
> >   if (!processing_template_decl
> >       && !cp_function_chain->can_throw
> >       && !flag_non_call_exceptions
> >       && !decl_replaceable_p (fndecl))
> >     TREE_NOTHROW (fndecl) = 1;
> >
> > P::P() should have been marked as can_throw in set_flags_from_callee, but when
> > processing X::X() cfun is null, so we can't set it.  P::P() is created only
> > later via implicitly_declare_fn.
> 
> This should be handled by bot_manip (under break_out_target_exprs,
> under get_nsdmi), but it seems that it currently only calls
> set_flags_from_callee for CALL_EXPR, not for AGGR_INIT_EXPR as we have
> in this case.

Ah, nice!  So, this tweaks set_flags_from_callee to also work for
AGGR_INIT_EXPRs.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2018-05-16  Marek Polacek  <polacek@redhat.com>

	PR c++/85363
	* call.c (set_flags_from_callee): Handle AGGR_INIT_EXPRs too.
	* tree.c (bot_manip): Call set_flags_from_callee for
	AGGR_INIT_EXPRs too.

	* g++.dg/cpp0x/initlist-throw1.C: New test.
	* g++.dg/cpp0x/initlist-throw2.C: New test.

diff --git gcc/cp/call.c gcc/cp/call.c
index 09a3618b007..11b40747932 100644
--- gcc/cp/call.c
+++ gcc/cp/call.c
@@ -319,16 +319,23 @@ build_call_n (tree function, int n, ...)
 void
 set_flags_from_callee (tree call)
 {
-  bool nothrow;
-  tree decl = get_callee_fndecl (call);
+  /* Handle both CALL_EXPRs and AGGR_INIT_EXPRs.  */
+  tree decl = cp_get_callee_fndecl_nofold (call);
 
   /* We check both the decl and the type; a function may be known not to
      throw without being declared throw().  */
-  nothrow = decl && TREE_NOTHROW (decl);
-  if (CALL_EXPR_FN (call))
-    nothrow |= TYPE_NOTHROW_P (TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (call))));
-  else if (internal_fn_flags (CALL_EXPR_IFN (call)) & ECF_NOTHROW)
-    nothrow = true;
+  bool nothrow = decl && TREE_NOTHROW (decl);
+  if (TREE_CODE (call) == CALL_EXPR)
+    {
+      if (CALL_EXPR_FN (call))
+	nothrow
+	  |= TYPE_NOTHROW_P (TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (call))));
+      else if (internal_fn_flags (CALL_EXPR_IFN (call)) & ECF_NOTHROW)
+	nothrow = true;
+    }
+  else if (AGGR_INIT_EXPR_FN (call))
+    nothrow
+      |= TYPE_NOTHROW_P (TREE_TYPE (TREE_TYPE (AGGR_INIT_EXPR_FN (call))));
 
   if (!nothrow && at_function_scope_p () && cfun && cp_function_chain)
     cp_function_chain->can_throw = 1;
diff --git gcc/cp/tree.c gcc/cp/tree.c
index ecb88df23b9..db81da91676 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -2987,7 +2987,7 @@ bot_manip (tree* tp, int* walk_subtrees, void* data_)
 
   /* Make a copy of this node.  */
   t = copy_tree_r (tp, walk_subtrees, NULL);
-  if (TREE_CODE (*tp) == CALL_EXPR)
+  if (TREE_CODE (*tp) == CALL_EXPR || TREE_CODE (*tp) == AGGR_INIT_EXPR)
     set_flags_from_callee (*tp);
   if (data.clear_location && EXPR_HAS_LOCATION (*tp))
     SET_EXPR_LOCATION (*tp, input_location);
diff --git gcc/testsuite/g++.dg/cpp0x/initlist-throw1.C gcc/testsuite/g++.dg/cpp0x/initlist-throw1.C
index e69de29bb2d..264c6c7a7a0 100644
--- gcc/testsuite/g++.dg/cpp0x/initlist-throw1.C
+++ gcc/testsuite/g++.dg/cpp0x/initlist-throw1.C
@@ -0,0 +1,29 @@
+// PR c++/85363
+// { dg-do run { target c++11 } }
+
+int
+init (int f)
+{
+  throw f;
+}
+
+struct X {
+  X (int f) : n {init (f)} {}
+  int n;
+};
+
+struct P {
+  X x{20};
+};
+
+int
+main ()
+{
+  try {
+    P p {};
+  }
+  catch (int n) {
+    return 0;
+  }
+  return 1;
+}
diff --git gcc/testsuite/g++.dg/cpp0x/initlist-throw2.C gcc/testsuite/g++.dg/cpp0x/initlist-throw2.C
index e69de29bb2d..2bb05834d9e 100644
--- gcc/testsuite/g++.dg/cpp0x/initlist-throw2.C
+++ gcc/testsuite/g++.dg/cpp0x/initlist-throw2.C
@@ -0,0 +1,33 @@
+// PR c++/85363
+// { dg-do run { target c++11 } }
+
+int
+init (int f)
+{
+  throw f;
+}
+
+struct X {
+  X () : n {init (42)} {}
+  int n;
+};
+
+struct P {
+  struct R {
+    struct Q {
+      X x = {};
+    } q;
+  } r;
+};
+
+int
+main ()
+{
+  try {
+    P p {};
+  }
+  catch (int n) {
+    return 0;
+  }
+  return 1;
+}


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