Use correct length calculation for int formatting to ensure format_le…

…ngth works Add tests Fixes #49
seanmiddleditch · Jan 15, 2024 · 75135c3 · 75135c3
1 parent 8046821
commit 75135c3
Show file tree

Hide file tree

Showing 2 changed files with 13 additions and 3 deletions.
diff --git a/source/format.cpp b/source/format.cpp
@@ -535,9 +535,9 @@ namespace NANOFMT_NS {
             0,
         };
 
-        size_t const available = out.end - out.pos;
-        size_t const length =
-            (spec.precision >= 0 && static_cast<std::size_t>(spec.precision) < available) ? spec.precision : available;
+        size_t const length = (spec.precision >= 0 && static_cast<std::size_t>(spec.precision) < sizeof(chars))
+            ? spec.precision
+            : sizeof(chars);
 
         const char* const end = to_chars(chars, chars + length, value, select_int_format(spec.type));
         format_int_chars(out, chars, end - chars, value < 0, spec);

diff --git a/tests/test_format.cpp b/tests/test_format.cpp
@@ -237,6 +237,16 @@ TEST_CASE("nanofmt.format.custom", "[nanofmt][format][custom]") {
     CHECK(sformat("{}", fwd_only_type{}) == "fwd_only_type");
 }
 
+TEST_CASE("nanofmt.format.length", "[nanofmt][format][length]") {
+    using namespace NANOFMT_NS;
+
+    CHECK(format_length("{}") == 0);
+    CHECK(format_length("{}", 777) == 3);
+
+    // https://github.com/seanmiddleditch/nanofmt/issues/49
+    CHECK(format_length("{0} = 0x{0:X} = 0b{0:b}", 28) == 19);
+}
+
 // TEST_CASE("nanofmt.format.compile_error", "[nanofmt][format][error]") {
 //    using namespace NANOFMT_NS::test;
 //