Work around undef conversion of large double to float

...as flagged by -fsanitize=undefined.  But is it really undefined?
[conv.double] "If the source value is between two adjacent destination values,
the result of the conversion is an implementation-defined choice of either of
those values."  So if the double is between std::numeric_limits<float>::max()
and std::numeric_limits<float>::infinity()...

Change-Id: I6389c8ac4a922991e240638d231dd2a39e173882

1 files changed, 17 insertions, 2 deletions

diff --git a/sal/rtl/ustring.cxx b/sal/rtl/ustring.cxx
index f10e755bbc7b..a79c9177a3ee 100644
--- a/sal/rtl/ustring.cxx
+++ b/sal/rtl/ustring.cxx
@@ -148,11 +148,26 @@ sal_Int32 SAL_CALL rtl_ustr_valueOfDouble(sal_Unicode * pStr, double d)
     return nLen;
 }
 
+namespace {
+
+// Avoid -fsanitize=undefined warning e.g. "runtime error: value 1e+99 is
+// outside the range of representable values of type 'float'":
+float doubleToFloat(double x) {
+    return
+        x < -std::numeric_limits<float>::max()
+        ? -std::numeric_limits<float>::infinity()
+        : x > std::numeric_limits<float>::max()
+        ? std::numeric_limits<float>::infinity()
+        : static_cast<float>(x);
+}
+
+}
+
 float SAL_CALL rtl_ustr_toFloat(sal_Unicode const * pStr) SAL_THROW_EXTERN_C()
 {
-    return (float) rtl_math_uStringToDouble(pStr,
+    return doubleToFloat(rtl_math_uStringToDouble(pStr,
                                             pStr + rtl_ustr_getLength(pStr),
-                                            '.', 0, 0, 0);
+                                            '.', 0, 0, 0));
 }
 
 double SAL_CALL rtl_ustr_toDouble(sal_Unicode const * pStr) SAL_THROW_EXTERN_C()