hadrian: Always canonicalize topDirectory

Hadrian's topDirectory is intended to provide an absolute path to the root of the GHC tree. However, if the tree is reached via a symlink this

One question here is whether the canonicalizePath call is expensive enough to warrant caching. In a quick microbenchmark I observed that canonicalizePath "." takes around 10us per call; this seems sufficiently low not to worry.

Alternatively, another approach here would have been to rather move the canonicalization into m4/fp_find_root.m4. This would have avoided repeated canonicalization but sadly path canonicalization is a hard problem in POSIX shell.

Addresses #22451 (closed).

mentioned in issue #22451 (closed)

The commit message, first paragraph, seems to be missing the last half of a sentence. :)

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I will attempt to batch this MR (!10751 (closed))...

Merged in 5efa9ca5

closed

Marking for backport to %9.8.1 and %9.6.3 due #23833.

added backport needed:9.6 backport needed:9.8 labels

mentioned in issue #23833

mentioned in merge request !11116 (merged)

removed backport needed:9.8 label

Backported to %9.8.1 in !11116 (merged) .

mentioned in merge request !11203 (merged)

Backported to %9.6.3 in !11203 (merged)

removed backport needed:9.6 label