Argument passing rules for unions and vectors are ambiguous
The psABI's rules for classifying unions, aggregates and vector types are ambiguous, so compilers pass the same type differently.
Tier II · Emerging Problems that are still building up.
3 public reports · first reported 2 September 2020 · last reported 20 November 2025
What's going wrong
Compiler and toolchain developers, plus people writing cross-compiler libraries, report that the x86-64 psABI leaves argument-passing rules open for some types.
AI-assisted: written with the help of AI from the reports. The idea report has the full summary.
In the idea report
- The full summary.
- The products the 3 reports are about, and how many came each month.
- Related problems.
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