[BinaryPlatforms] Change "shortest match" algorithm to "best match" #49502
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My assertion in the previous attempt to fix this issue was incorrect:
> We define a simpler match as one that has fewer tags overall.
> As these candidate matches have already been filtered to match the
> given platform, the only other tags that exist are ones that are in
> addition to the tags declared by the platform. Hence, selecting the
> minimum in number of tags is equivalent to selecting the closest match.
This is demonstrably false, by my own test case:
```
platforms = Dict(
Platform("x86_64", "linux") => "bad",
Platform("x86_64", "linux"; sanitize="memory") => "good",
)
select_platform(platforms, Platform("x86_64", "linux"; sanitize="memory")) == "good"
```
In this case, because there exists a candidate that is _more general_
than the provided platform type, the shortest match is no longer the
best match.
This PR performs a more rigorous matching that works more reliably in
all cases.
|
This fixes #49491 |
|
@StefanKarpinski I'm totally open to the idea of using natural sort here; but such a sort function needs to be available pretty early on in the bootstrap process; do we have one? |
staticfloat
commented
Apr 25, 2023
| @@ -330,8 +330,7 @@ end | |||
| # Ambiguity test | |||
| @test select_platform(platforms, P("aarch64", "linux")) == "linux3" | |||
| @test select_platform(platforms, P("aarch64", "linux"; libgfortran_version=v"3")) == "linux3" | |||
| # This one may be surprising, but we still match `linux3`, and since linux3 is shorter, we choose it. | |||
| @test select_platform(platforms, P("aarch64", "linux"; libgfortran_version=v"3", libstdcxx_version=v"3.4.18")) === "linux3" | |||
| @test select_platform(platforms, P("aarch64", "linux"; libgfortran_version=v"3", libstdcxx_version=v"3.4.18")) === "linux5" | |||
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As an aside, this "surprise" should have been my hint that my previous implementation was incorrect.
|
I think this looks better now, thanks! |
51 tasks
|
Removing backport since original PR causing this was reverted on 1.9. |
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My assertion in the previous attempt to fix this issue was incorrect:
This is demonstrably false, by my own test case:
In this case, because there exists a candidate that is more general than the provided platform type, the shortest match is no longer the best match.
This PR performs a more rigorous matching that works more reliably in all cases.