Fix {name:Type} hints being dropped when an earlier brace is not a type hint

[polyglotAI-bot]

Description

Fixes #510.

SqlParameterTypeExtractor.TryExtractParameter located the name/type separator with an unbounded sql.IndexOf(':', startIndex + 1), and the type scan ran to the first } anywhere in the query. A { that is not a type hint — {name} with no type, an unterminated {name:Type, or a brace the outer scanner does not skip — therefore latched onto the colon (or closing brace) of a later parameter: the extractor recorded a garbage parameter name and advanced the scan past that later parameter, so its genuine hint was silently dropped and the parameter fell back to CLR-type inference. That is observable data loss, e.g. the query SELECT 1 AS `x{y`, {dt:DateTime64(3, 'UTC')} resolved dt as DateTime('UTC'), truncating the sub-second part. The method's own doc comment already promised that {name} without a type is simply "not included".

The fix bounds both scans to the parameter's own braces: the name must be a single run of identifier characters (ASCII word characters plus $), optionally surrounded by whitespace, and the type scan stops at an opening brace. When a brace does not hold a hint, TryExtractParameter returns no match and the caller advances one character, so any following hint is still scanned. The accepted name grammar was checked against ClickHouse 26.5: { a : Int32 }, {$p_1:Int32} and {1a:Int32} are accepted by the server, while {a.b:Int32}, {a-b:Int32}, {a b:Int32} and a { inside a type definition are syntax errors.

This is a separate root cause from #508 and is not addressed by #509 — the two touch neighbouring code in the same file, so whichever merges second will need a trivial rebase.

Changes

• ClickHouse.Driver/ADO/Parameters/SqlParameterTypeExtractor.cs: bound the separator search to the parameter's own name (identifier run, optional surrounding whitespace); stop the type scan at {; add an IsParameterNameChar helper.
• CHANGELOG.md / RELEASENOTES.md: bug-fix entry.

Test

• SqlParameterTypeExtractorTests: parametrized ExtractTypeHints_BraceWithoutTypeHintPrecedingHint_HintStillExtracted (10 cases: {a}, { }, a colon in a following comment, a non-identifier name, an unterminated brace, an unterminated {a:Int32, a brace inside a quoted identifier) asserts the later hint is still extracted and no garbage key is produced; ExtractTypeHints_ParameterWithoutType_NotIncluded pins the documented {name} contract; ExtractTypeHints_NameThatIsNotAnIdentifier_NotIncluded pins the server-invalid names; ExtractTypeHints_UnusualButValidParameterName_ReturnsType is the contrast case that names which are valid server-side ($p_1, 1a, a newline before the colon) still yield their hint.
• ParameterCollectionTests.ResolveTypeNames_HintPrecededByBraceWithoutType_UsesHint: covers the live client resolution path (ClickHouseParameterCollection.ResolveTypeNames, what ClickHouseClient.PostSqlQueryAsync calls) and fails on main with DateTime('UTC') instead of DateTime64(3, 'UTC').
• All 15 added cases fail on main and pass with the fix; --filter "FullyQualifiedName~Parameter|FullyQualifiedName~SQL" is green (4105 passed) against a live ClickHouse 26.5 server. No existing test was modified.

Pre-PR validation gate

• Deterministic repro confirmed
• Root cause documented above
• Fix targets the root cause
• Test fails without fix, passes with fix
• No existing tests broken or weakened
• Convention compliance verified per AGENTS.md (test naming, TestCase parametrization, CHANGELOG + RELEASENOTES, no public API change)

[Copilot]

Pull request overview

This PR fixes a correctness bug in the ADO parameter type-hint scanner ({name:Type}) where a preceding { that is not a type hint (e.g., {name} or an unterminated {name:Type) could cause the extractor to latch onto a later parameter’s :/} and silently drop the real hint—leading to incorrect type resolution and potential data loss (e.g., DateTime64 truncation).

Changes:

• Tighten {name:Type} parsing so the : separator search is bounded to a single identifier-like name (with optional surrounding whitespace), preventing later hints from being skipped.
• Stop the type scan when encountering a new { (treating the current parameter as unterminated rather than consuming the next parameter).
• Add targeted unit tests (extractor-level + ClickHouseParameterCollection.ResolveTypeNames path) and document the fix in CHANGELOG.md / RELEASENOTES.md.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
ClickHouse.Driver/ADO/Parameters/SqlParameterTypeExtractor.cs	Bounds name/type scanning to the current brace pair and enforces identifier-like parameter names to prevent dropped hints/garbage keys.
ClickHouse.Driver.Tests/ADO/SqlParameterTypeExtractorTests.cs	Adds parametrized regression coverage for braces that are not type hints and for valid/invalid parameter-name shapes.
ClickHouse.Driver.Tests/ParameterCollectionTests.cs	Adds a regression test for the real resolution pipeline (ResolveTypeNames) to ensure the later hint is honored.
CHANGELOG.md	Adds an Unreleased bug-fix entry for issue #510.
RELEASENOTES.md	Adds the same Unreleased bug-fix entry for issue #510.

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.