Fix incorrect zero padding of inf and NaN (#77)

We now follow the rule: if the type is a non-finite floating point type,
*and* the stream fill has been zero padded, then reset it to ' '.

This prevents zero-padded numbers which turn out to be nan/inf from
being oddly formatted with leading zeros.

Author: c42f

tinyformat.h

@@ -144,6 +144,7 @@ namespace tfm = tinyformat;
 #include <algorithm>
 #include <iostream>
 #include <sstream>
+#include <cmath>
 
 #ifndef TINYFORMAT_ASSERT
 #   include <cassert>
@@ -297,6 +298,21 @@ TINYFORMAT_DEFINE_FORMAT_TRUNCATED_CSTR(const char)
 TINYFORMAT_DEFINE_FORMAT_TRUNCATED_CSTR(char)
 #undef TINYFORMAT_DEFINE_FORMAT_TRUNCATED_CSTR
 
+template<typename T>
+void spaceFillIfNotFinite(std::ostream& out, const T& value) { }
+// TODO: type_traits would clearly be better here. Should consider moving all
+// these workarounds into a big pre-C++11 section.
+#define TINYFORMAT_SETFILL_NOT_FINITE_FLOATING(type)        \
+void spaceFillIfNotFinite(std::ostream& out, type value)    \
+{                                                           \
+    if (out.fill() == '0' && !std::isfinite(value))         \
+        out.fill(' ');                                      \
+}
+TINYFORMAT_SETFILL_NOT_FINITE_FLOATING(float)
+TINYFORMAT_SETFILL_NOT_FINITE_FLOATING(double)
+TINYFORMAT_SETFILL_NOT_FINITE_FLOATING(long double)
+#undef TINYFORMAT_SETFILL_NOT_FINITE_FLOATING
+
 } // namespace detail
 
 
@@ -333,6 +349,7 @@ inline void formatValue(std::ostream& out, const char* /*fmtBegin*/,
     // could otherwise lead to a crash when printing a dangling (const char*).
     const bool canConvertToChar = detail::is_convertible<T,char>::value;
     const bool canConvertToVoidPtr = detail::is_convertible<T, const void*>::value;
+    detail::spaceFillIfNotFinite(out, value);
     if (canConvertToChar && *(fmtEnd-1) == 'c')
         detail::formatValueAsType<T, char>::invoke(out, value);
     else if (canConvertToVoidPtr && *(fmtEnd-1) == 'p')

tinyformat_test.cpp

@@ -11,6 +11,7 @@ namespace std { class type_info; }
 
 #include <stdexcept>
 #include <climits>
+#include <limits>
 #include <cfloat>
 #include <cstddef>
 
@@ -212,6 +213,16 @@ int unitTests()
     CHECK_EQUAL(tfm::format("%1$10.*2$f", 1234.1234567890, 4), " 1234.1235");
     CHECK_EQUAL(tfm::format("%1$*3$.*2$f", 1234.1234567890, 4, 10), " 1234.1235");
     CHECK_EQUAL(tfm::format("%1$*2$.*3$f", 1234.1234567890, -10, 4), "1234.1235 ");
+    // Test padding for infinity and NaN
+    // (Visual Studio 12.0 and earlier print these in a different way)
+#   if !defined(_MSC_VER) || _MSC_VER >= 1900
+    CHECK_EQUAL(tfm::format("%.3d",   std::numeric_limits<double>::infinity()), "inf");
+    CHECK_EQUAL(tfm::format("%.4d",   std::numeric_limits<double>::infinity()), " inf");
+    CHECK_EQUAL(tfm::format("%04.0f", std::numeric_limits<double>::infinity()), " inf");
+    CHECK_EQUAL(tfm::format("%.3d",   std::numeric_limits<double>::quiet_NaN()), "nan");
+    CHECK_EQUAL(tfm::format("%.4d",   std::numeric_limits<double>::quiet_NaN()), " nan");
+    CHECK_EQUAL(tfm::format("%04.0f", std::numeric_limits<double>::quiet_NaN()), " nan");
+#   endif
 
     //------------------------------------------------------------
     // Test flags