Measure display width in tuple formatter #4631
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barcharcraz
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May 14, 2024
StephanTLavavej
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May 16, 2024
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I'm speculatively mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed. |
barcharcraz
approved these changes
May 20, 2024
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Thanks for fixing this runtime correctness bug in a hopefully-popular new feature! 😻 🐞 🛠️ |
JMazurkiewicz
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May 26, 2024
Addresses microsoft#4631
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Currently, the tuple formatter uses
static_cast<int>(_Tmp_buf.size())to compute the width of output (in order to determine the number of fill characters to insert). This gives the wrong width if_Tmp_buf.size()is larger thanINT_MAX(see<format>: Misbehavior for huge strings #4479).Both problems can be avoided by using
_Measure_string_prefix, which computes the display width and clamps the result toINT_MAX(which means no fill character will be inserted).Closes #4479
While working on this, I noticed that the tuple formatter test uses
\u00d6which cannot be represented in some legacy text encodings. This PR adjusted the test to make it encoding-independent.Closes #4635
Future work: if no width is specified in the format string, there should be no need to use a temporary buffer. The use of
_Tmp_bufshould be skipped in this case.