Fix #17017 (math edge cases) (#17588)

* Fix #17017

Add more test cases

* USe signbit in example

lib/pure/math.nim

@@ -949,18 +949,25 @@ func frexp*[T: float32|float64](x: T): tuple[frac: T, exp: int] {.inline.} =
     doAssert frexp(8.0) == (0.5, 4)
     doAssert frexp(-8.0) == (-0.5, 4)
     doAssert frexp(0.0) == (0.0, 0)
+
     # special cases:
-    when not defined(windows):
-      doAssert frexp(-0.0) == (-0.0, 0) # signbit preserved for +-0
-      doAssert frexp(Inf).frac == Inf # +- Inf preserved
-      doAssert frexp(NaN).frac.isNaN
+    doAssert frexp(-0.0).frac.signbit # signbit preserved for +-0
+    doAssert frexp(Inf).frac == Inf # +- Inf preserved
+    doAssert frexp(NaN).frac.isNaN
+
   when not defined(js):
     var exp: cint
     result.frac = c_frexp2(x, exp)
     result.exp = exp
   else:
     if x == 0.0:
-      result = (0.0, 0)
+      # reuse signbit implementation
+      let uintBuffer = toBitsImpl(x)
+      if (uintBuffer[1] shr 31) != 0:
+        # x is -0.0
+        result = (-0.0, 0)
+      else:
+        result = (0.0, 0)
     elif x < 0.0:
       result = frexp(-x)
       result.frac = -result.frac
@@ -980,6 +987,7 @@ func frexp*[T: float32|float64](x: T, exponent: var int): T {.inline.} =
     var x: int
     doAssert frexp(5.0, x) == 0.625
     doAssert x == 3
+
   (result, exponent) = frexp(x)
 
 

tests/stdlib/tmath.nim

@@ -29,10 +29,6 @@ template main() =
       doAssert erf(6.0) > erf(5.0)
       doAssert erfc(6.0) < erfc(5.0)
 
-  when not defined(js) and not defined(windows): # xxx pending bug #17017
-    doAssert gamma(-1.0).isNaN
-
-
   block: # sgn() tests
     doAssert sgn(1'i8) == 1
     doAssert sgn(1'i16) == 1
@@ -46,6 +42,7 @@ template main() =
     doAssert sgn(123.9834'f64) == 1
     doAssert sgn(0'i32) == 0
     doAssert sgn(0'f32) == 0
+    doAssert sgn(-0.0'f64) == 0
     doAssert sgn(NegInf) == -1
     doAssert sgn(Inf) == 1
     doAssert sgn(NaN) == 0
@@ -358,7 +355,7 @@ template main() =
     doAssert almostEqual(prod([1.5, 3.4]), 5.1)
     let x: seq[float] = @[]
     doAssert prod(x) == 1.0
-  
+
   block: # clamp range
     doAssert clamp(10, 1..5) == 5
     doAssert clamp(3, 1..5) == 3
@@ -370,8 +367,42 @@ template main() =
     doAssert a1.clamp(a2..a4) == a2
     doAssert clamp((3, 0), (1, 0) .. (2, 9)) == (2, 9)
 
-  when not defined(windows): # xxx pending bug #17017
-    doAssert sqrt(-1.0).isNaN
+  block: # edge cases
+    doAssert sqrt(-4.0).isNaN
+
+    doAssert ln(0.0) == -Inf
+    doAssert ln(-0.0) == -Inf
+    doAssert ln(-12.0).isNaN
+
+    doAssert log10(0.0) == -Inf
+    doAssert log10(-0.0) == -Inf
+    doAssert log10(-12.0).isNaN
+
+    doAssert log2(0.0) == -Inf
+    doAssert log2(-0.0) == -Inf
+    doAssert log2(-12.0).isNaN
+
+    when nimvm: discard
+    else:
+      doAssert frexp(0.0) == (0.0, 0)
+      doAssert frexp(-0.0) == (-0.0, 0)
+      doAssert classify(frexp(-0.0)[0]) == fcNegZero
+
+    when not defined(js):
+      doAssert gamma(0.0) == Inf
+      doAssert gamma(-0.0) == -Inf
+      doAssert gamma(-1.0).isNaN
+
+      doAssert lgamma(0.0) == Inf
+      doAssert lgamma(-0.0) == Inf
+      doAssert lgamma(-1.0) == Inf
+
+      when nimvm: discard
+      else:
+        var exponent: cint
+        doAssert c_frexp(0.0, exponent) == 0.0
+        doAssert c_frexp(-0.0, exponent) == -0.0
+        doAssert classify(c_frexp(-0.0, exponent)) == fcNegZero
 
 static: main()
 main()