Add public API to BinaryLogger for parsing parameter strings

[Copilot]

Fixes #12256

Context

dotnet-watch needs to parse the file path from the /bl command line option without duplicating MSBuild's parsing logic. This PR adds a public API to the BinaryLogger that exposes the parameter parsing functionality.

Changes Made

New Public API:

• Added BinaryLoggerParameters class to hold parsed logger parameters with properties:
  • LogFilePath - The parsed file path (null for wildcards or when unspecified)
  • ProjectImportsCollectionMode - Import collection mode (None/Embed/ZipFile)
  • OmitInitialInfo - Whether to omit initial info
  • HasProjectImportsParameter (internal) - Tracks if ProjectImports was explicitly specified
• Added BinaryLogger.ParseParameters(string) static method that parses semicolon-delimited parameter strings

Implementation Changes:

• Refactored internal ProcessParameters() to use the new public API
• Extracted parameter string literals to private constants (LogFileParameterPrefix, BinlogFileExtension, OmitInitialInfoParameter, ProjectImportsNoneParameter, ProjectImportsEmbedParameter, ProjectImportsZipFileParameter)
• Added helper methods TryParseProjectImports() and TrySetProjectImportsMode() for cleaner parsing logic
• Simplified TryParseProjectImports() to use || operator for more concise code

Bug Fix:

• Fixed issue where manually setting CollectProjectImports before calling Initialize() would be overridden by parameter parsing

Code Quality Improvements:

• Using early returns with continue statements instead of nested if-else blocks
• Extracted duplicate code into helper methods
• Improved readability with || operator for short-circuit evaluation

Testing

• ✅ Added 19 comprehensive unit tests for the new ParseParameters API
  • Tests for valid parameters (file paths, imports modes, OmitInitialInfo)
  • Tests for wildcard paths (returns null as per design)
  • Tests for null and invalid parameters (throws LoggerException)
• ✅ All new tests pass
• ✅ Fixed 2 tests broken by refactoring (ZipFile tests)
• ✅ Full build succeeds
• ⚠️ 3 pre-existing TestBinaryLoggerRoundtrip failures (not caused by this PR)

Notes

Usage Example:

var parsed = BinaryLogger.ParseParameters("LogFile=build.binlog;ProjectImports=None");
Console.WriteLine(parsed.LogFilePath); // "build.binlog"
Console.WriteLine(parsed.ProjectImportsCollectionMode); // None

Important: Wildcard paths ({}) return null for LogFilePath as expansion requires runtime context (timestamp, process ID) only available during logger initialization.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add public API to BinaryLogger that parses its parameter string</issue_title>
<issue_description>The string is parsed in

msbuild/src/Build/Logging/BinaryLogger/BinaryLogger.cs

Line 481 in 7f69ea9

private bool TryInterpretPathParameter(string parameter, out string filePath)

We need to parse the file path out of the /bl command line option in dotnet-watch and need to replicate the parsing logic.
</issue_description>

Comments on the Issue (you are @copilot in this section)

@MichalPavlik @baronfel / @rainersigwald We could make the method static—as it should be—but I’m leaning toward making it internal and introducing a new friend assembly. I’m hesitant to expand the public API surface. What are your thoughts? :) @baronfel The binary logger itself is already public - I think that there should be a matching typed structure for the parameters that all loggers accept, and parsing methods for those structures should be part of the public API for those loggers. This is the only sane way to keep parity across the CLI and API usage of these loggers.

Fixes #12256

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[YuliiaKovalova]

@copilot fix the tests you broke

[Copilot]

@copilot fix the tests you broke

Fixed in commit e9c8db7. The issue was that my refactored parameter parsing was unconditionally setting CollectProjectImports from the parsed parameters, overwriting any manually-set property value. Added a HasProjectImportsParameter flag to only set it when explicitly specified in the parameters string.

The BinaryLoggerShouldEmbedFilesViaTaskOutput and BinaryLoggerShouldEmbedSymlinkFilesViaTaskOutput tests now pass.

Note: The 3 TestBinaryLoggerRoundtrip test failures are pre-existing (they also fail on the base commit 338e820) and were not caused by my changes.

[Copilot]

Pull Request Overview

This PR adds a public API for parsing BinaryLogger parameter strings to address the need from dotnet-watch to parse /bl command line options without duplicating MSBuild's parsing logic.

Key Changes:

• Introduced BinaryLoggerParameters class to encapsulate parsed logger parameters
• Added public BinaryLogger.ParseParameters() static method for parsing parameter strings
• Refactored internal parameter processing to use the new public API
• Fixed a bug where manually setting CollectProjectImports before Initialize() would be overridden

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 9 comments.

File	Description
src/Build/Logging/BinaryLogger/BinaryLogger.cs	Added public API (BinaryLoggerParameters class and ParseParameters method), refactored internal ProcessParameters to use the new API, and introduced helper methods for parsing
src/Build.UnitTests/BinaryLogger_Tests.cs	Added comprehensive tests for ParseParameters method covering valid parameters, wildcard paths, and error cases

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