Fix string::assign and ::resize_and_overwrite under ASan
#3956
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strega-nil-ms
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Aug 15, 2023
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strega-nil-ms
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Thanks for fixing my mistake -.-
The argument may alias `*this`, so don't shrink until after we copy the characters.
We need to update the buffer info even if we do not allocate.
Compare the converted "result size" to the "new size" so we don't need to suppress C4108. Improves readability and throughput a teeny bit.
string::assign under ASanstring::assign and ::resize_and_overwrite under ASan
CaseyCarter
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Aug 15, 2023
strega-nil
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Aug 15, 2023
StephanTLavavej
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Aug 16, 2023
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Sorry for my oversight😿 I've add a test for the problem introduced by my "fix". |
StephanTLavavej
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Aug 16, 2023
CaseyCarter
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Aug 16, 2023
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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed. |
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Thanks for fixing these bugs in one of the STL's most popular types and one of MSVC's most important new features! 😻 🐞 🛠️ |
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Fixes #3955 / VSO-1854254 / AB#1854254 (fix string's self-assignment with offset via pointers under ASan)
Fixes VSO-1854245 / AB#1854245 "ASan issue in
basic_string::assign(pointer)"Fixes VSO-1854251 / AB#1854251 "ASan issue in
basic_string::assign(iterator, iterator)"Fixes VSO-1854242 / AB#1854242 "ASan issue in
tests/std/P0980R1_constexpr_strings[basic_string::resize_and_overwrite]"Drive-by: In
resize_and_overwrite, compare the converted result size so we need not suppress the "comparing signed and unsigned" warning.Test coverage for the latter three fixes will be in the ASan test coverage that's incoming in the near future.