MSBuild's property tracking capabilities

MSBuild Property Tracking is a built-in diagnostic feature that tracks property value changes during the build process. By default, this feature is opted out due to performance considerations.

Property Tracking Coverage

The implementation tracks properties in the following scenarios:

1. Properties set via command-line arguments (e.g. using /p: switches)
2. Properties defined based on environment variables and used by MSBuild
3. Properties set as target outputs
   • Tracks changes when properties are modified by target execution
4. Properties set as task outputs
   • Monitors property modifications resulting from task execution
5. Properties defined in XML during evaluation
   • Provides exact location information for properties defined in project files
   • Includes line and column information from the source XML
   • Reports on property modifications

Event Types and Message Formatting

The feature implements specialized event handling for four tracking scenarios (plus a 'None' option to disable tracking):

1. PropertyReassignmentEventArgs

   • Triggered when a property value is changed
   • set MsBuildLogPropertyTracking=1
   • Note: Property reassignment tracking is automatically enabled with ChangeWaves.Wave17_10, even when MsBuildLogPropertyTracking=0

2. PropertyInitialValueSetEventArgs

   • Triggered when a property is first initialized
   • set MsBuildLogPropertyTracking=2

3. EnvironmentVariableRead

   • Tracks when environment variables are read
   • set MsBuildLogPropertyTracking=4

4. UninitializedPropertyReadEventArgs

   • Triggered when attempting to read a property that hasn't been initialized
   • set MsBuildLogPropertyTracking=8

5. None

   • Disables explicit property tracking (but see note below about PropertyReassignment)
   • set MsBuildLogPropertyTracking=0

If you want to enable all these events reporting, enable it by set MsBuildLogPropertyTracking=15.

Special Behavior for PropertyReassignment

Property reassignment tracking has special enabling logic. It is enabled when:

• PropertyReassignment flag is explicitly set (value includes 1), OR
• MsBuildLogPropertyTracking=0 AND ChangeWaves.Wave17_10 features are enabled

This means that in projects with Wave17_10 enabled, property reassignments will be tracked even when property tracking appears to be disabled.