Support -uptr mode in xdrpp

[graydon]

This adopts the xdrpp changes in https://github.com/xdrpp/xdrpp/tree/cxx20-rebase-2026-09-01 and adds an optional --enable-xdrpp-uptr flag to configure that switches on the newly-supported-on-that-branch -uptr mode in xdrpp.

[Copilot]

Copilot review overview

🟡 Changes recommended

Generated headers can remain stale when toggling the option, and the new build mode lacks automated coverage.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Regenerate headers when --enable-xdrpp-uptr changes · New
• Add CI coverage for --enable-xdrpp-uptr mode · New

What changed in this PR

Adds optional pointer-backed XDR union generation and updates XDR query validation for the newer xdrpp API.

Changes:

• Adds --enable-xdrpp-uptr.
• Passes -uptr during XDR header generation.
• Uses union metadata to validate fields without copying unions.

File	Description
configure.ac	Defines the optional uptr configuration flag.
src/​Makefile.am	Passes configured flags to xdrc.
src/​util/​xdrquery/​XDRFieldResolver.h	Adapts union-field validation to the new API.

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[Copilot]

Copilot review overview

🔵 Needs a closer look

Generated headers are not invalidated when the mode changes, and the new build variant lacks CI coverage.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Regenerate headers when --enable-xdrpp-uptr changes
• Add CI coverage for --enable-xdrpp-uptr mode

[Copilot]

Copilot review overview

🔵 Needs a closer look

The -uptr path lacks CI coverage, incremental builds may retain stale headers, and a required standard header is not directly included.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Regenerate headers when --enable-xdrpp-uptr changes
• Add CI coverage for --enable-xdrpp-uptr mode

[Copilot]

Copilot review overview

🔵 Needs a closer look

The generated-header dependency and CI coverage issues must be addressed before approval.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Regenerate headers when --enable-xdrpp-uptr changes
• Add CI coverage for --enable-xdrpp-uptr mode

[Copilot]

Copilot review overview

🟡 Changes recommended

The build rule has a critical clean-build failure, and the new mode lacks CI coverage.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Missing output directory creation breaks clean out-of-tree builds · New
• Add CI coverage for --enable-xdrpp-uptr mode

Resolved since last review (1)

• Regenerate headers when --enable-xdrpp-uptr changes

[Copilot]

Copilot review overview

🟡 Changes recommended

The missing include and lack of CI coverage for the new supported mode must be addressed.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1

Open (1)

• Include <string_view> or avoid direct string_view usage · New

Resolved since last review (2)

• Missing output directory creation breaks clean out-of-tree builds
• Add CI coverage for --enable-xdrpp-uptr mode

[Copilot]

Copilot review overview

🟡 Changes recommended

The default configuration selects an invalid empty threshold, and the new storage modes lack CI coverage.

Get a fresh assessment by requesting another Copilot review.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Default configure emits an invalid empty uptr threshold · New
• Add CI coverage for all-indirect and threshold uptr modes · New

Resolved since last review (1)

• Include <string_view> or avoid direct string_view usage

[Copilot]

Copilot review overview

🟡 Changes recommended

Empty option validation remains faulty, and the new union-storage modes are not exercised by CI.

Review effort: Balanced
Findings: 2

Open (2)

• Reject empty --enable-xdrpp-uptr value during configuration · New
• Add CI coverage for all-indirect and threshold uptr modes

Resolved since last review (1)

• Default configure emits an invalid empty uptr threshold

[Copilot]

Copilot review overview

🟡 Changes recommended

Dependency incompatibilities block builds, union validation accepts invalid paths, and unchanged headers repeatedly regenerate.

Review effort: Balanced
Findings: 1 · 3

Open (4)

• Align xdrpp dependency with required xdrc interfaces · New
• Prevent repeated regeneration when unchanged headers retain old timestamps · New
• Stop traversal after matching a union arm · New
• Add CI coverage for all-indirect and threshold uptr modes

Resolved since last review (1)

• Reject empty --enable-xdrpp-uptr value during configuration

[Copilot]

Copilot review overview

🟡 Changes recommended

Parallel recovery of missing generated headers can launch competing generators and fail the build.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Avoid parallel regeneration races for missing headers · New
• Add CI coverage for all-indirect and threshold uptr modes

Resolved since last review (3)

• Align xdrpp dependency with required xdrc interfaces
• Stop traversal after matching a union arm
• Prevent repeated regeneration when unchanged headers retain old timestamps

[Copilot]

Copilot review overview

🔵 Needs a closer look

The default union-storage change needs human review backed by build, runtime, and performance validation against the adopted xdrpp revision.

Review effort: Balanced
Findings: 1

Open (1)

• Add CI coverage for all-indirect and threshold uptr modes

Resolved since last review (1)

• Avoid parallel regeneration races for missing headers

[Copilot]

Copilot review overview

🔵 Needs a closer look

The default changes storage layouts across core XDR types and needs full build and runtime validation before human approval.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Add CI coverage for all-indirect and threshold uptr modes

[Copilot]

Copilot review overview

🔵 Needs a closer look

Default-on changes to core XDR storage layouts require human confirmation of dependency compatibility, runtime correctness, and performance.

Review effort: Balanced
Findings: None