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Inline char constants as Unicode string literals in SQL Server IndexO… - #39104
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AndriySvyryd merged 3 commits intoOct 3, 2026
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…f/Replace translations
SqlServerStringMethodTranslator applied CharTypeMapping to char arguments of
string.IndexOf(char) and string.Replace(char, char). CharTypeMapping's literal has
no N prefix, so a constant such as 'ş' or '中' was emitted as a non-Unicode literal
and best-fit mapped to the database code page before the comparison: on the
default collation `CHARINDEX('ş', N'aşb')` returns 0 while `CHARINDEX('ş', N'asb')`
returns 2, and `REPLACE(N'Şişlis', 'ş', 'x')` replaces the trailing 's'. Passing the
same char as a parameter (sent as nvarchar) gave the right answer, and an
ExecuteUpdate with an inline char could silently corrupt data.
Emit char constants as string constants with the string argument's type mapping
(N'ş' for nvarchar columns) and keep CharTypeMapping only for non-constant char
expressions. Existing baselines change from 'e' to N'e' accordingly; a varchar
column still gets a non-Unicode literal.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Copilot review overview
🟡 Changes recommended
SQL Server bulk-update and non-Unicode column regression tests are still needed.
Review effort: Lite
Findings: 1
Open (1)
What changed in this PR
Fixes SQL Server IndexOf(char) and Replace(char, char) translations so constant characters use the string mapping and preserve Unicode behavior.
Changes:
- Adds Unicode-safe constant character translation.
- Adds non-ASCII regression coverage and updates provider baselines.
- Preserves character mapping for non-constant expressions.
| File | Description |
|---|---|
test/EFCore.SqlServer.FunctionalTests/Query/Translations/StringTranslationsSqlServerTest.cs |
Updates SQL Server translation baselines and tests. |
test/EFCore.Sqlite.FunctionalTests/Query/Translations/StringTranslationsSqliteTest.cs |
Updates SQLite translation baselines. |
test/EFCore.Specification.Tests/Query/Translations/StringTranslationsTestBase.cs |
Adds provider-independent regression tests. |
test/EFCore.Cosmos.FunctionalTests/Query/Translations/StringTranslationsCosmosTest.cs |
Updates Cosmos translation baselines. |
src/EFCore.SqlServer/Query/Internal/Translators/SqlServerStringMethodTranslator.cs |
Applies string mappings to constant character arguments. |
…onstant Covers the bulk-update path: without the fix the inline 'ş' was emitted as a non-Unicode literal, so REPLACE never matched the appended 'ş' and the stored value was left as "...ş" instead of "...x". Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
AndriySvyryd
reviewed
Oct 2, 2026
…erver SQL Server has no char type, so a non-constant char (e.g. a parameter) is now sent as a one-character string via a CharToStringConverter composed on the string type mapping instead of using CharTypeMapping. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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…f/Replace translations
SqlServerStringMethodTranslator applied CharTypeMapping to char arguments of string.IndexOf(char) and string.Replace(char, char). CharTypeMapping's literal has no N prefix, so a constant such as 'ş' or '中' was emitted as a non-Unicode literal and best-fit mapped to the database code page before the comparison: on the default collation
CHARINDEX('ş', N'aşb')returns 0 whileCHARINDEX('ş', N'asb')returns 2, andREPLACE(N'Şişlis', 'ş', 'x')replaces the trailing 's'. Passing the same char as a parameter (sent as nvarchar) gave the right answer, and an ExecuteUpdate with an inline char could silently corrupt data.Emit char constants as string constants with the string argument's type mapping (N'ş' for nvarchar columns) and keep CharTypeMapping only for non-constant char expressions. Existing baselines change from 'e' to N'e' accordingly; a varchar column still gets a non-Unicode literal.