<format>: Alternate form general floating-point width handling (#5261)

alexprabhat99 · alexprabhatbara · web-flow · commit 3f7ca671925c · 2025-02-10T21:12:10.000-08:00
Co-authored-by: alexprabhatbara &lt;alex.prabhat@idrive.com&gt;
diff --git a/stl/inc/format b/stl/inc/format
@@ -2145,6 +2145,8 @@ _NODISCARD _OutputIt _Fmt_write(
     case 'g':
         if (_Precision == -1) {
             _Precision = 6;
+        } else if (_Precision == 0) {
+            _Precision = 1;
         }
         _Format = chars_format::general;
         break;
diff --git a/tests/std/tests/P0645R10_text_formatting_formatting/test.cpp b/tests/std/tests/P0645R10_text_formatting_formatting/test.cpp
@@ -835,6 +835,7 @@ void test_float_specs() {
     assert(format(STR("{:3}"), Float{0}) == STR("  0"));
     assert(format(STR("{:#9G}"), Float{12.2}) == STR("  12.2000"));
     assert(format(STR("{:#12g}"), Float{1'000'000}) == STR(" 1.00000e+06"));
+    assert(format(STR("[{:#6.0g}]"), 1.234e-37) == STR("[1.e-37]"));
 
     // Precision
     Float value = 1234.52734375;

Original file line number	Diff line number	Diff line change
`@@ -2145,6 +2145,8 @@ _NODISCARD _OutputIt _Fmt_write(`
`2145`	`2145`	`case 'g':`
`2146`	`2146`	`if (_Precision == -1) {`
`2147`	`2147`	`_Precision = 6;`
	`2148`	`+ } else if (_Precision == 0) {`
	`2149`	`+ _Precision = 1;`
`2148`	`2150`	`}`
`2149`	`2151`	`_Format = chars_format::general;`
`2150`	`2152`	`break;`