<format>: fix std::format("{:#.precision}", floating) (#3815)

Co-authored-by: A. Jiang <de34@live.cn> Co-authored-by: Stephan T. Lavavej <stl@nuwen.net>
microsoft · Jun 22, 2023 · 057adf2 · 057adf2
1 parent 4768199
commit 057adf2
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Showing 5 changed files with 42 additions and 10 deletions.
diff --git a/stl/inc/format b/stl/inc/format
@@ -2867,7 +2867,7 @@ _NODISCARD _OutputIt _Fmt_write(
 
  auto _To_upper = false;
  auto _Format = chars_format::general;
- auto _Exponent = '\0';
+ auto _Exponent = 'e';
  auto _Precision = _Specs._Precision;
 
  switch (_Specs._Type) {
@@ -2885,8 +2885,7 @@ _NODISCARD _OutputIt _Fmt_write(
  if (_Precision == -1) {
  _Precision = 6;
  }
- _Format = chars_format::scientific;
- _Exponent = 'e';
+ _Format = chars_format::scientific;
  break;
  case 'F':
  _To_upper = true;
@@ -2904,8 +2903,7 @@ _NODISCARD _OutputIt _Fmt_write(
  if (_Precision == -1) {
  _Precision = 6;
  }
- _Format = chars_format::general;
- _Exponent = 'e';
+ _Format = chars_format::general;
  break;
  }
 
@@ -3018,7 +3016,7 @@ _NODISCARD _OutputIt _Fmt_write(
  _Zeroes_to_append = _Extra_precision;
  break;
  case chars_format::general:
- if (_Specs._Alt) {
+ if (_Specs._Alt && (_Specs._Type == 'g' || _Specs._Type == 'G')) {
  auto _Digits = static_cast<int>(_Exponent_start - _Buffer_start);
 
  if (!_Append_decimal) {

diff --git a/tests/libcxx/expected_results.txt b/tests/libcxx/expected_results.txt
@@ -1062,11 +1062,7 @@ std/ranges/range.adaptors/range.take/adaptor.pass.cpp FAIL
 std/ranges/range.factories/range.single.view/cpo.pass.cpp FAIL
 std/thread/futures/futures.task/futures.task.members/ctor2.compile.pass.cpp FAIL
 std/utilities/format/format.functions/escaped_output.ascii.pass.cpp FAIL
-std/utilities/format/format.functions/format.locale.pass.cpp FAIL
-std/utilities/format/format.functions/format.pass.cpp FAIL
 std/utilities/format/format.functions/locale-specific_form.pass.cpp FAIL
-std/utilities/format/format.functions/vformat.locale.pass.cpp FAIL
-std/utilities/format/format.functions/vformat.pass.cpp FAIL
 std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/ctad.static.compile.pass.cpp FAIL
 std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.inv/invoke.pass.cpp:0 FAIL
 std/utilities/function.objects/refwrap/refwrap.const/type_conv_ctor.pass.cpp:0 FAIL

diff --git a/tests/std/test.lst b/tests/std/test.lst
@@ -218,6 +218,7 @@ tests\GH_002769_handle_deque_block_pointers
 tests\GH_002789_Hash_vec_Tidy
 tests\GH_002989_nothrow_unwrappable
 tests\GH_002992_unwrappable_iter_sent_pairs
+tests\GH_003003_format_decimal_point
 tests\GH_003022_substr_allocator
 tests\GH_003105_piecewise_densities
 tests\GH_003119_error_category_ctor

diff --git a/tests/std/tests/GH_003003_format_decimal_point/env.lst b/tests/std/tests/GH_003003_format_decimal_point/env.lst
@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\concepts_20_matrix.lst
diff --git a/tests/std/tests/GH_003003_format_decimal_point/test.cpp b/tests/std/tests/GH_003003_format_decimal_point/test.cpp
@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <cassert>
+#include <format>
+
+int main() {
+ assert(std::format("{:#.0}", 0.0) == "0.");
+ assert(std::format("{:#.1}", 0.0) == "0.");
+ assert(std::format("{:#.2}", 0.0) == "0.");
+
+ assert(std::format("{:#.0}", 1200.0) == "1.e+03");
+ assert(std::format("{:#.1}", 1200.0) == "1.e+03");
+ assert(std::format("{:#.2}", 1200.0) == "1.2e+03");
+ assert(std::format("{:#.3}", 1200.0) == "1.2e+03");
+ assert(std::format("{:#.4}", 1200.0) == "1200.");
+ assert(std::format("{:#.5}", 1200.0) == "1200.");
+ assert(std::format("{:#.6}", 1200.0) == "1200.");
+
+ assert(std::format("{:#.0}", 0.123) == "0.1");
+ assert(std::format("{:#.1}", 0.123) == "0.1");
+ assert(std::format("{:#.2}", 0.123) == "0.12");
+ assert(std::format("{:#.3}", 0.123) == "0.123");
+ assert(std::format("{:#.4}", 0.123) == "0.123");
+ assert(std::format("{:#.5}", 0.123) == "0.123");
+
+ assert(std::format("{:#.0}", 10.1) == "1.e+01");
+ assert(std::format("{:#.1}", 10.1) == "1.e+01");
+ assert(std::format("{:#.2}", 10.1) == "10.");
+ assert(std::format("{:#.3}", 10.1) == "10.1");
+ assert(std::format("{:#.4}", 10.1) == "10.1");
+ assert(std::format("{:#.5}", 10.1) == "10.1");
+}