-
e2f2f9d0
by Vladislav Zavialov at 2025-04-20T10:53:39-04:00
Add name for -Wunusable-unpack-pragmas
This warning had no name or flag and was triggered unconditionally.
Now it is part of -Wdefault.
In GHC.Tc.TyCl.tcTyClGroupsPass's strict mode, we now have to
force-enable this warning to ensure that detection of flawed groups
continues to work even if the user disables the warning with the
-Wno-unusable-unpack-pragmas option. Test case: T3990c
Also, the misnamed BackpackUnpackAbstractType is now called
UnusableUnpackPragma.
-
6caa6508
by Adam Gundry at 2025-04-20T10:54:22-04:00
Fix specialisation of incoherent instances (fixes #25883)
GHC normally assumes that class constraints are canonical, meaning that
the specialiser is allowed to replace one dictionary argument with another
provided that they have the same type. The `-fno-specialise-incoherents`
flag alters INCOHERENT instance definitions so that they will prevent
specialisation in some cases, by inserting `nospec`.
This commit fixes a bug in 7124e4ad76d98f1fc246ada4fd7bf64413ff2f2e, which
treated some INCOHERENT instance matches as if `-fno-specialise-incoherents`
was in effect, thereby unnecessarily preventing specialisation. In addition
it updates the relevant `Note [Rules for instance lookup]` and adds a new
`Note [Canonicity for incoherent matches]`.
-
0426fd6c
by Adam Gundry at 2025-04-20T10:54:23-04:00
Add regression test for #23429
-
eec96527
by Adam Gundry at 2025-04-20T10:54:23-04:00
user's guide: update specification of overlapping/incoherent instances
The description of the instance resolution algorithm in the user's
guide was slightly out of date, because it mentioned in-scope given
constraints only at the end, whereas the implementation checks for
their presence before any of the other steps.
This also adds a warning to the user's guide about the impact of
incoherent instances on specialisation, and more clearly documents
some of the other effects of `-XIncoherentInstances`.
-
a00eeaec
by Matthew Craven at 2025-04-20T10:55:03-04:00
Fix bytecode generation for `tagToEnum# <LITERAL>`
Fixes #25975.
-
2e204269
by Andreas Klebinger at 2025-04-22T12:20:41+02:00
Simplifier: Constant fold invald tagToEnum# calls to bottom expr.
When applying tagToEnum# to a out-of-range value it's best to simply
constant fold it to a bottom expression. That potentially allows more
dead code elimination and makes debugging easier.
Fixes #25976
-
65f42301
by Matthew Pickering at 2025-04-22T10:22:59-04:00
Move -fno-code note into Downsweep module
This note was left behind when all the code which referred to it was
moved into the GHC.Driver.Downsweep module
-
4e091736
by Matthew Pickering at 2025-04-22T10:23:00-04:00
Apply editing notes to Note [-fno-code mode] suggested by sheaf
These notes were suggested in https://gitlab.haskell.org/ghc/ghc/-/merge_requests/14241