Reexported modules, take 3 #397
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In #385, we claimed to exploit the fact that GHC only needs package names in reexport declarations to obviate the need for knowing the versions (and dependency hashes) of all prebuilt packages. We provided a test to substantiate this indeed works. But it turns that the test was not a good test. The test was flawed because it featured libraries reexporting `base`. It turns out that `base` (along with `rts`) are magical in GHC. Because they are so-called "wired-in packages", they are assumed unique and are therefore not located using a version number. So while the scheme in #385 worked for `base`, it didn't work in the general case, as observed by @lunaris. The fix consists qualifying all package reexports with full package id's, not package names. How do we derive a package id given only a package name? The solution is to have the toolchain generate a dump of the global package database that ships with the compiler. This is only needed once for the entire workspace. From this dump, we can lookup the full package id given any particular name. Fixes #357.
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lunaris
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In #385, we claimed to exploit the fact that GHC only needs package
names in reexport declarations to obviate the need for knowing the
versions (and dependency hashes) of all prebuilt packages. We provided
a test to substantiate this indeed works. But it turns that the test
was not a good test.
The test was flawed because it featured libraries reexporting
base.It turns out that
base(along withrts) are magical in GHC.Because they are so-called "wired-in packages", they are assumed
unique and are therefore not located using a version number. So while
the scheme in #385 worked for
base, it didn't work in the generalcase, as observed by @lunaris.
The fix consists qualifying all package reexports with full package
id's, not package names. How do we derive a package id given only
a package name? The solution is to have the toolchain generate a dump
of the global package database that ships with the compiler. This is
only needed once for the entire workspace. From this dump, we can
lookup the full package id given any particular name.
Fixes #357.