Handle mpq_class(0,1)

3 files changed, 14 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 005ada450..09e7e0114 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-31  Marc Glisse  <marc.glisse@inria.fr>
+
+	* gmpxx.h (mpq_class::mpq_class): Handle mpq_class(0,1).
+	* tests/cxx/t-constr.cc: Test it.
+
 2012-05-30  Torbjorn Granlund  <tege@gmplib.org>
 
 	* mpn/x86_64 (FUNC_ENTRY): New name for DOS64_ENTRY.
diff --git a/gmpxx.h b/gmpxx.h
index d47757864..450f37568 100644
--- a/gmpxx.h
+++ b/gmpxx.h
@@ -1641,7 +1641,14 @@ public:
   explicit __gmp_expr(const char *s, int base = 0)
   {
     mpq_init (mp);
-    if (mpq_set_str(mp, s, base) != 0)
+    // If s is the literal 0, we meant to call another constructor.
+    // If s just happens to evaluate to 0, we would crash, so whatever.
+    if (s == 0)
+      {
+	// Don't turn mpq_class(0,0) into 0
+	mpz_set_si(mpq_denref(mp), base);
+      }
+    else if (mpq_set_str(mp, s, base) != 0)
       {
         mpq_clear (mp);
         throw std::invalid_argument ("mpq_set_str");
diff --git a/tests/cxx/t-constr.cc b/tests/cxx/t-constr.cc
index 6d588d31d..fb26c3370 100644
--- a/tests/cxx/t-constr.cc
+++ b/tests/cxx/t-constr.cc
@@ -320,6 +320,7 @@ check_mpq (void)
     const char *a = "FFFF";
     int base = 16;
     mpq_class b(a, base); ASSERT_ALWAYS(b == 65535u);
+    mpq_class c(0, 1); ASSERT_ALWAYS(c == 0);
   }
 
   // mpq_class(const std::string &)