Introduce mode for project graph construction to load entire graph

[jeffkl]

Enables accurate NuGet package dependency resolution across all target frameworks and configurations.

Context

NuGet Package Manager needs to resolve package dependencies for restore operations. The current ProjectGraphMode.Default only loads projects needed for a specific build, which would require separate graph constructions for each target framework. By providing a complete graph that includes all outer and inner builds regardless of SetTargetFramework constraints, NuGet can efficiently perform package resolution in a single pass. This is especially important for multi-targeted projects where different frameworks may have different dependencies.

Changes Made

Introduced a new ProjectGraphOptions struct because project graph construction happens in a constructor and adding a new overload seemed like a worse design. This way we can add new options to the struct and not keep having to modify the constructor.

var projectGraph = new ProjectGraph(
    new ProjectGraphOptions
    {
        EntryPoints = [new ProjectGraphEntryPoint("path")],
        Mode = ProjectGraphMode.Full
    });

In the new ProjectGraphMode.Full mode:

• SetTargetFramework metadata is ignored during graph construction
• All outer and inner builds are evaluated, regardless of framework filters
• This provides a complete view of the dependency graph needed for restore operations
• Note: Using the "full" graph for an actual build would technically overbuild, but it's the correct mode for package resolution

Testing

Added unit test demonstrating that ProjectGraphMode.Full loads all target framework instances even when SetTargetFramework would normally filter them.

Had to fix a few tests that were broken. These tests are marked as inactive and it wasn't caught.

Notes

[Copilot]

Pull request overview

This PR adds a new options-based construction API for ProjectGraph and introduces a new “Full” graph-construction mode intended to load/evaluate the entire project graph (ignoring SetTargetFramework constraints during construction) for restore scenarios.

Changes:

• Added ProjectGraphOptions (and ProjectGraphMode) and a new ProjectGraph(ProjectGraphOptions, ...) constructor.
• Threaded graph mode through GraphBuilder/ProjectInterpretation and added logic to ignore SetTargetFramework in Full mode.
• Added a new unit test intended to validate Full-mode behavior with multitargeting + SetTargetFramework.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/Build/Microsoft.Build.csproj	Includes the new ProjectGraphOptions.cs in the build.
src/Build/Graph/ProjectInterpretation.cs	Adds Full-mode reference enumeration behavior (ignoring SetTargetFramework).
src/Build/Graph/ProjectGraphOptions.cs	Introduces ProjectGraphOptions and ProjectGraphMode public API surface.
src/Build/Graph/ProjectGraph.cs	Adds an options-based constructor and routes existing constructors through it.
src/Build/Graph/GraphBuilder.cs	Passes graph mode into reference parsing to enable mode-specific behavior.
src/Build.UnitTests/Graph/ProjectGraph_Tests.cs	Adds a new test intended to cover Full-mode graph construction behavior.

[JanProvaznik]

/review

[JanProvaznik]

MSBuild triage: @jeffkl could you please elaborate in the description on the business value?

[github-actions]

❌ Expert Code Review (command) failed. Please review the logs for details.

ChangeWave Discipline — LGTM

No ChangeWave is required. The new behavior activates only when the caller explicitly constructs new ProjectGraphOptions { Mode = ProjectGraphMode.Full }. The default value is ProjectGraphMode.Default = 0, so every existing call site — including all callers of new ProjectGraph(...) — receives exactly the same behavior as before. There is no scenario in which an existing build changes behavior without a deliberate code change by the consuming developer. ChangeWaves exist to protect users from implicit behavioral changes; this PR introduces no such change.

[AlesProkop]

LGTM