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

2 files changed, 35 insertions, 4 deletions

diff --git a/sal/qa/rtl/oustring/rtl_OUString2.cxx b/sal/qa/rtl/oustring/rtl_OUString2.cxx
index 849c5215dd16..27a06ab43464 100644
--- a/sal/qa/rtl/oustring/rtl_OUString2.cxx
+++ b/sal/qa/rtl/oustring/rtl_OUString2.cxx
@@ -23,6 +23,7 @@
 #include <stdio.h>
 
 #include <algorithm>
+#include <limits>
 
 #include <cppunit/TestFixture.h>
 #include <cppunit/extensions/HelperMacros.h>
@@ -34,6 +35,21 @@
 namespace rtl_OUString
 {
 
+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);
+}
+
+}
+
 class number : public CppUnit::TestFixture
 {
     void number_float_test_impl(float _nValue)
@@ -43,7 +59,7 @@ class number : public CppUnit::TestFixture
             sValue <<= suValue;
             printf("nFloat := %.9f  sValue := %s\n", _nValue, sValue.getStr());
 
-            float nValueATOF = static_cast<float>(atof( sValue.getStr() ));
+            double nValueATOF = doubleToFloat(atof( sValue.getStr() ));
 
             bool bEqualResult = is_float_equal(_nValue, nValueATOF);
             CPPUNIT_ASSERT_MESSAGE("Values are not equal.", bEqualResult == true);
@@ -439,7 +455,7 @@ sal_Int16 SAL_CALL checkPrecisionSize()
         void toFloat_test_impl(rtl::OString const& _sValue)
             {
                 //printf("the original str is %s\n", _sValue.getStr());
-                float nValueATOF = static_cast<float>(atof( _sValue.getStr() ));
+                float nValueATOF = doubleToFloat(atof( _sValue.getStr() ));
         //printf("the original str is %.10f\n", nValueATOF);
                 rtl::OUString suValue = rtl::OUString::createFromAscii( _sValue.getStr() );
                 float nValueToFloat = suValue.toFloat();
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()