From bd516e342969a7f5acfb36d87bba21c3e7ee9f7f Mon Sep 17 00:00:00 2001
From: Victor Zverovich <victor.zverovich@gmail.com>
Date: Sun, 21 Apr 2019 07:39:41 -0700
Subject: [PATCH] Convert negative precision to zero in printf (#1127)

and remove redundant check in grisu2_prettify.
---
 include/fmt/format.h | 3 +--
 include/fmt/printf.h | 2 +-
 test/printf-test.cc  | 6 +++++-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/fmt/format.h b/include/fmt/format.h
index e9f29518..0e8fb2e4 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -1181,8 +1181,7 @@ It grisu2_prettify(const char* digits, int size, int exp, It it,
     *it++ = static_cast<Char>(params.upper ? 'E' : 'e');
     return write_exponent<Char>(exp, it);
   }
-  const int exp_threshold = 21;
-  if (size <= full_exp && full_exp <= exp_threshold) {
+  if (size <= full_exp) {
     // 1234e7 -> 12340000000[.0+]
     it = copy_str<Char>(digits, digits + size, it);
     it = std::fill_n(it, full_exp - size, static_cast<Char>('0'));
diff --git a/include/fmt/printf.h b/include/fmt/printf.h
index dd553139..f75f10af 100644
--- a/include/fmt/printf.h
+++ b/include/fmt/printf.h
@@ -44,7 +44,7 @@ class printf_precision_handler : public function<int> {
   int operator()(T value) {
     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
       FMT_THROW(format_error("number is too big"));
-    return static_cast<int>(value);
+    return (std::max)(static_cast<int>(value), 0);
   }
 
   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
diff --git a/test/printf-test.cc b/test/printf-test.cc
index c0108103..ab199d2c 100644
--- a/test/printf-test.cc
+++ b/test/printf-test.cc
@@ -520,6 +520,10 @@ TEST(PrintfTest, CheckFormatStringRegression) {
   check_format_string_regression("%c%s", 'x', "");
 }
 
+TEST(PrintfTest, FixedLargeExponent) {
+  EXPECT_EQ("1000000000000000000000", fmt::sprintf("%.*f", -13, 1e21));
+}
+
 TEST(PrintfTest, VSPrintfMakeArgsExample) {
   fmt::format_arg_store<fmt::printf_context, int, const char*> as{42,
                                                                   "something"};
@@ -599,7 +603,7 @@ std::string custom_format(const char* format_str, const Args&... args) {
   return custom_vformat(format_str, va);
 }
 
-TEST(CustomFormatterTest, Format) {
+TEST(PrintfTest, CustomFormat) {
   EXPECT_EQ("0.00", custom_format("%.2f", -.00001));
   EXPECT_EQ("0.00", custom_format("%.2f", .00001));
   EXPECT_EQ("1.00", custom_format("%.2f", 1.00001));