[PATCH] c++: satisfaction value of type typedef to bool [PR95386]

[Patrick Palka]

On Fri, 29 May 2020, Jason Merrill wrote:

> On 5/29/20 11:59 AM, Patrick Palka wrote:
> > In the testcase below, the satisfaction value of fn1<int>'s constraint
> > is INTEGER_CST '1' of type BOOLEAN_TYPE value_type, which is a typedef
> > to the standard boolean_type_node.  But satisfaction_value expects to
> > see exactly boolean_true_node or integer_one_node, which this value is
> > neither, causing us to trip over the assert therein.
> > 
> > This patch relaxes satisfaction_value to accept any INTEGER_CST which
> > satisfies integer_zerop or integer_onep.  (It seems we could get away
> > with accepting only INTEGER_CSTs of type BOOLEAN_TYPE, but that wouldn't
> > be a proper relaxation of what the subroutine currently accepts and
> > would therefore be more risky to backport.)
> 
> I think for GCC 11 I'd prefer to restrict it to BOOLEAN_TYPE.  This patch is
> OK for GCC 10.

Sounds good.  Would the following be OK for GCC 11 after a full
bootstrap and regtest?

I opted to mirror satisfy_atom and instead check
same_type_p (..., boolean_type_node).

-- >8 --

Subject: [PATCH] c++: satisfaction value of type typedef to bool [PR95386]

In the testcase below, the satisfaction value of fn1<int>'s constraint
is INTEGER_CST '1' of type BOOLEAN_TYPE value_type, which is a typedef
to the standard boolean_type_node.  But satisfaction_value expects to
see exactly boolean_true_node or integer_one_node, which this value is
neither, causing us to trip over the assert therein.

This patch changes satisfaction_value to accept INTEGER_CST of any
boolean type.

gcc/cp/ChangeLog:

	PR c++/95386
	* constraint.cc (satisfaction_value): Accept INTEGER_CST of any
	boolean type.

gcc/testsuite/ChangeLog:

	PR c++/95386
	* g++.dg/concepts/pr95386.C: New test.
---
 gcc/cp/constraint.cc                    | 14 +++++++-------
 gcc/testsuite/g++.dg/concepts/pr95386.C | 11 +++++++++++
 2 files changed, 18 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/concepts/pr95386.C

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index eb72bfe5936..92ff283013e 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -2490,15 +2490,15 @@ satisfy_disjunction (tree t, tree args, subst_info info)
 tree
 satisfaction_value (tree t)
 {
-  if (t == error_mark_node)
+  if (t == error_mark_node || t == boolean_true_node || t == boolean_false_node)
     return t;
-  if (t == boolean_true_node || t == integer_one_node)
-    return boolean_true_node;
-  if (t == boolean_false_node || t == integer_zero_node)
-    return boolean_false_node;
 
-  /* Anything else should be invalid.  */
-  gcc_assert (false);
+  gcc_assert (TREE_CODE (t) == INTEGER_CST
+	      && same_type_p (TREE_TYPE (t), boolean_type_node));
+  if (integer_zerop (t))
+    return boolean_false_node;
+  else
+    return boolean_true_node;
 }
 
 /* Build a new template argument list with template arguments corresponding
diff --git a/gcc/testsuite/g++.dg/concepts/pr95386.C b/gcc/testsuite/g++.dg/concepts/pr95386.C
new file mode 100644
index 00000000000..3c683e5693c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/pr95386.C
@@ -0,0 +1,11 @@
+// PR c++/95386
+// { dg-do compile { target concepts } }
+
+template <typename> struct blah {
+ typedef bool value_type;
+ constexpr operator value_type() { return false; }
+};
+
+template <class T> void fn1(T) requires (!blah<T>());
+
+void fn2() { fn1(0); }
-- 
2.27.0.rc1.5.gae92ac8ae3


> 
> > Passes 'make check-c++', does this look OK to commit to master and to
> > the GCC 10 branch after a full bootstrap and regtest?
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	PR c++/95386
> > 	* constraint.cc (satisfaction_value): Relax to accept any
> > 	INTEGER_CST that satisfies integer_zerop or integer_onep.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	PR c++/95386
> > 	* g++.dg/concepts/pr95386.C: New test.
> > ---
> >   gcc/cp/constraint.cc                    |  7 ++++---
> >   gcc/testsuite/g++.dg/concepts/pr95386.C | 11 +++++++++++
> >   2 files changed, 15 insertions(+), 3 deletions(-)
> >   create mode 100644 gcc/testsuite/g++.dg/concepts/pr95386.C
> > 
> > diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> > index eb72bfe5936..5a247cfb738 100644
> > --- a/gcc/cp/constraint.cc
> > +++ b/gcc/cp/constraint.cc
> > @@ -2490,11 +2490,12 @@ satisfy_disjunction (tree t, tree args, subst_info
> > info)
> >   tree
> >   satisfaction_value (tree t)
> >   {
> > -  if (t == error_mark_node)
> > +  if (t == error_mark_node || t == boolean_true_node || t ==
> > boolean_false_node)
> >       return t;
> > -  if (t == boolean_true_node || t == integer_one_node)
> > +  gcc_assert (TREE_CODE (t) == INTEGER_CST);
> > +  if (integer_onep (t))
> >       return boolean_true_node;
> > -  if (t == boolean_false_node || t == integer_zero_node)
> > +  if (integer_zerop (t))
> >       return boolean_false_node;
> >       /* Anything else should be invalid.  */
> > diff --git a/gcc/testsuite/g++.dg/concepts/pr95386.C
> > b/gcc/testsuite/g++.dg/concepts/pr95386.C
> > new file mode 100644
> > index 00000000000..3c683e5693c
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/concepts/pr95386.C
> > @@ -0,0 +1,11 @@
> > +// PR c++/95386
> > +// { dg-do compile { target concepts } }
> > +
> > +template <typename> struct blah {
> > + typedef bool value_type;
> > + constexpr operator value_type() { return false; }
> > +};
> > +
> > +template <class T> void fn1(T) requires (!blah<T>());
> > +
> > +void fn2() { fn1(0); }
> > 
> 
>