[release/10.0] Fix GO batch separator not recognized in comments and escaped identifiers

[Copilot]

Fixes #37494

Description

EF Core splits SQL Server migration scripts into batches on lines starting with GO. To avoid splitting inside string literals, SqlServerMigrationsSqlGenerator tracks whether it is inside a quoted string.

The implementation does not handle standard SQL block comments (/* ... */). If a block comment contains a single quote, the quoted state is incorrectly toggled even though the quote is inside a comment. Since there is no matching closing quote, quoted toggle remains true across subsequent lines. As a result, a later GO line is not recognized as a batch separator and is sent to SQL Server as literal text, causing:

Microsoft.Data.SqlClient.SqlException: Incorrect syntax near 'go'.

Customer impact

Customers using SQL migrations with stored procedures or other SQL scripts that include block comments containing single quotes will experience migration failures with "Incorrect syntax near 'go'" errors. This can occur when documentation comments in SQL scripts use contractions or possessives (e.g., "It's", "user's").

Workarounds:

• Remove single quotes from block comments
• Use two single quotes in block comments to escape them

How found

Customer reported on 10.0.1

Regression

Yes, from EF Core 9.0. Introduced in #34917.

Testing

Added 31 tests covering:

• Block comments with single quotes (single-line and multi-line)
• Line comments with block comment markers
• Empty block comments
• Block comments with line comments inside
• Escaped identifiers with square brackets [GO] and double quotes "GO"
• Escaped closing brackets in identifiers [g]]o]
• Escaped double quotes in identifiers "go""lum"
• Multi-line escaped identifiers spanning newlines with go text inside (e.g., INSERT INTO "\ngo\n" VALUES (1))
• All character combinations (quotes, slashes, asterisks, dashes, brackets) preceding GO
• Line comments (--) inside quotes and escaped identifiers
• Unclosed delimiters within block comments (e.g., /* [bracket */ - valid SQL since comments don't require matched delimiters)
• Unclosed delimiters within line comments (e.g., -- [column - valid SQL since line comments end at EOL)
• Single quotes inside block comments
• All delimiter types inside line comments
• Escaped quotes in strings ('test''s value')
• Multiple delimiters in strings

Risk

Medium, because the fix entails changes to a parser, so all the possible consequences aren't as clear. However, the changes only affect custom SQL operations in migrations.

[artl93]

Obviously, we want to avoid regression. The more we can add, the better, but otherwise, approved.

[roji]

Thanks for making the changes, this is now easier to follow and I can't think of any problems.