FIX: Comparing blocks with a 1.#NaN value

resolves: Oldes/Rebol-issues#2494

Author: Oldes

src/core/t-decimal.c

@@ -96,7 +96,7 @@ REBOOL almost_equal(REBDEC a, REBDEC b, REBCNT max_diff) {
 	REBI64 int_diff;
 
 #ifndef USE_NO_INFINITY
-	if(isnan(a) || isnan(b)) return FALSE;
+	if (isnan(a) && isnan(b)) return max_diff > 0;
 #endif // !USE_NO_INFINITY
 
 	ua.d = a;

src/tests/units/decimal-test.r3

@@ -257,6 +257,16 @@ Rebol [
 		--assert not ($0.0 == 0)
 		--assert not (0.0 == 0)
 
+	--test-- "NaN equality"
+	;@@  https://github.com/Oldes/Rebol-issues/issues/2494
+		--assert 1.#NaN = 1.#NaN
+		--assert not 1.#NaN != 1.#NaN
+		--assert not 1.#NaN == 1.#NaN
+		--assert 1.#NaN !== 1.#NaN
+		--assert same? 1.#NaN 1.#NaN
+		--assert equal? 1.#NaN 1.#NaN
+		--assert not strict-equal? 1.#NaN 1.#NaN
+
 ===end-group===
 
 ===start-group=== "trigonometric function"

src/tests/units/series-test.r3

@@ -1270,14 +1270,21 @@ Rebol [
 
 --test-- "SORT with NaN"
 	;@@ https://github.com/Oldes/Rebol-issues/issues/2493
-	; using `mold` in this test, because currently `(1.#NaN = 1.#NaN) == false` and so the test would fail! 
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#inf -1.0 1.#nan 1.0 -1.#inf 0 1.#NAN]
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#inf -1.0 1.#nan 1.0 -1.#inf 1.#NAN 0]
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#inf -1.0 1.#nan 1.0 1.#NAN -1.#inf 0]
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#inf -1.0 1.#nan 1.#NAN 1.0 -1.#inf 0]
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#inf 1.#NAN -1.0 1.#nan 1.0 -1.#inf 0]
-	--assert "[-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN]" = mold sort [1.#NAN 1.#inf -1.0 1.#nan 1.0 -1.#inf 0]
-
+	;@@ https://github.com/Oldes/Rebol-issues/issues/2494
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#inf -1.0 1.#nan 1.0 -1.#inf 0 1.#NAN]
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#inf -1.0 1.#nan 1.0 -1.#inf 1.#NAN 0]
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#inf -1.0 1.#nan 1.0 1.#NAN -1.#inf 0]
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#inf -1.0 1.#nan 1.#NAN 1.0 -1.#inf 0]
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#inf 1.#NAN -1.0 1.#nan 1.0 -1.#inf 0]
+	--assert [-1.#INF -1.0 0 1.0 1.#INF 1.#NaN 1.#NaN] = sort [1.#NAN 1.#inf -1.0 1.#nan 1.0 -1.#inf 0]
+	;reversed
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#inf -1.0 1.#nan 1.0 -1.#inf 0 1.#NAN]
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#inf -1.0 1.#nan 1.0 -1.#inf 1.#NAN 0]
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#inf -1.0 1.#nan 1.0 1.#NAN -1.#inf 0]
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#inf -1.0 1.#nan 1.#NAN 1.0 -1.#inf 0]
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#inf 1.#NAN -1.0 1.#nan 1.0 -1.#inf 0]
+	--assert [1.#NaN 1.#NaN 1.#INF 1.0 0 -1.0 -1.#INF] = sort/reverse [1.#NAN 1.#inf -1.0 1.#nan 1.0 -1.#inf 0]
+	
 ===end-group===