merge revision(s) 54492,54494,54495,54496,54499,54503: [Backport #12249]

	* math.c (ruby_tgamma): fix tgamma(-0.0) on mingw.
	  [ruby-core:74817] [Bug #12249]

	* math.c (ruby_lgamma_r): fix lgamma(-0.0) on mingw and OSX.

	* math.c (ruby_lgamma_r): mswin's lgamma_r also seems to be wrong.
	  cf. [Bug #12249]

	* math.c (ruby_lgamma_r): missing/lgamma_r.c is used on Windows,
	  since msvcrt does not provide it.

	* missing/lgamma_r.c (lgamma_r): fix lgamma(-0.0).
	  [ruby-core:74823] [Bug #12249]

	* configure.in (rb_cv_lgamma_r_m0): check if lgamma_r(-0.0)
	  returns negative infinity.  [Bug #12249]

	* math.c (ruby_lgamma_r): define by the configured result.

	* configure.in (rb_cv_lgamma_r_m0): fix the condition for
	  lgamma_r(-0.0).  [Bug #12249]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54643 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 26 insertions, 4 deletions

diff --git a/math.c b/math.c
index 591d6ae2f2..9ac898f0ba 100644
--- a/math.c
+++ b/math.c
@@ -734,14 +734,36 @@ math_erfc(VALUE obj, VALUE x)
     return DBL2NUM(erfc(Get_Double(x)));
 }
 
-#ifdef __MINGW32__
+#if defined __MINGW32__
 static inline double
-mingw_tgamma(const double d)
+ruby_tgamma(const double d)
 {
     const double g = tgamma(d);
-    return (isnan(g) && !signbit(d)) ? INFINITY : g;
+    if (isinf(g)) {
+	if (d == 0.0 && signbit(d)) return -INFINITY;
+    }
+    if (isnan(g)) {
+	if (!signbit(d)) return INFINITY;
+    }
+    return g;
+}
+#define tgamma(d) ruby_tgamma(d)
+#endif
+
+#if defined LGAMMA_R_M0_FIX
+static inline double
+ruby_lgamma_r(const double d, int *sign)
+{
+    const double g = lgamma_r(d, sign);
+    if (isinf(g)) {
+	if (d == 0.0 && signbit(d)) {
+	    *sign = -1;
+	    return INFINITY;
+	}
+    }
+    return g;
 }
-#define tgamma(d) mingw_tgamma(d)
+#define lgamma_r(d, sign) ruby_lgamma_r(d, sign)
 #endif
 
 /*