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This instance is only used in rare code paths such as HieFiles

We need something compactable here, as a FastString ends up getting
compacted.

This is a defensive incase someone tries to add back something which
mentions ByteString into a ModIface

See #17097

See #17097

This is towards being able to compact a ModIface (see #17097)

This is necessary as functions can't be compacted.

See #17097

Not sure this is the best choice but manipulating ShortByteStrings is
also awkward

This change will allow `ModIface` to be compacted.

Related to #17097

Douglas Wilson authored Apr 02, 2021 and Marge Bot committed Apr 09, 2021

Also includes small unrelated type fix

Matthew Pickering authored Apr 07, 2021 and Marge Bot committed Apr 09, 2021

The test max memory usage improves dramatically with the fixes to
memory usage in demand analyser from #15455

Matthew Pickering authored Apr 05, 2021 and Marge Bot committed Apr 09, 2021

There used to be some cases were kinds were not generalised properly
before being printed in GHCi. This seems to have changed in the past so
now it's uncessary to tidy before printing out the test case.

```
> :set -XPolyKinds
> data A x y
> :k A
k1 -> k2 -> A
```

This tidying was causing issues with an attempt to increase sharing by
making `mkTyConApp` (see !4762)

Matthew Pickering authored Apr 05, 2021 and Marge Bot committed Apr 09, 2021

The approach taking in this patch is that the tcl_bndrs in TcLclEnv are
zonked and tidied eagerly, so that work can be shared across multiple
calls to `relevant_bindings`.

To test this patch I tried without the `keepThisHole` filter and the
test finished quickly.

Fixes #14766

Peter Trommler authored Apr 02, 2021 and Marge Bot committed Apr 09, 2021

In commit f3c23939 T18623 is disabled for aarch64.
The limit seems to be too low for powerpc64le, too. This could be
because tables next to code is not supported and our code generator
produces larger code on PowerPC.

Andreas Klebinger authored Mar 31, 2021 and Marge Bot committed Apr 09, 2021

This allows us to use the unsafe shifts in non-debug builds for performance.
For older versions of base we instead export Data.Bits

See also #19618

Sylvain Henry authored Mar 03, 2021 and Marge Bot committed Apr 09, 2021

Metric Decrease:
    T16577

Alfredo Di Napoli authored Apr 06, 2021 and Marge Bot committed Apr 08, 2021

This commit moves the error-related functions in `GHC.Iface.Load` into
a brand new module called `GHC.Iface.Errors`. This will avoid boot files
and circular dependencies in the context of #18516, in the
pretty-printing modules.

Ryan Scott authored Apr 04, 2021 and Marge Bot committed Apr 08, 2021

Previously, associated type family instances would incorrectly claim to
implicitly quantify over type variables bound by the instance head in the
`HsOuterImplicit`s that `rnFamEqn` returned. This is fixed by using
`filterInScopeM` to filter out any type variables that the instance head
binds.

Fixes #19649.

Matthew Pickering authored Apr 07, 2021 and Marge Bot committed Apr 08, 2021

Fixes #11545

Matthew Pickering authored Mar 26, 2021 and Marge Bot committed Apr 08, 2021

This avoids a big spike in memory usage during demand analysis.

Part of fixing #15455

-------------------------
Metric Decrease:
    T18698a
    T18698b
    T9233
    T9675
    T9961
-------------------------

Matthew Pickering authored Mar 29, 2021 and Marge Bot committed Apr 08, 2021

It seems that these places were supposed to be forced anyway but the
forcing has no effect because the result was immediately placed in a
lazy box.

Matthew Pickering authored Mar 29, 2021 and Marge Bot committed Apr 08, 2021

In the particular case of `DmdEnv`, not applying this function strictly
meant 500MB of thunks were accumulated before the values were forced at
the end of demand analysis.

Matthew Pickering authored Mar 29, 2021 and Marge Bot committed Apr 08, 2021

This can lead to a classic thunk build-up in a TcRef

Fixes #19596

Matthew Pickering authored Mar 25, 2021 and Marge Bot committed Apr 08, 2021

Related to #15455

James Foster authored Mar 14, 2021 and vdukhovni committed Apr 07, 2021

And though partially applied foldl' is now again inlined, #4301 has not
resurfaced, and appears to be resolved.

Sylvain Henry authored Apr 06, 2021 and Marge Bot committed Apr 07, 2021

Dynamic-by-default was a mechanism to automatically select the -dynamic
way for some targets.

It was implemented in a convoluted way: it was defined as a flavour
option, hence it couldn't be passed as a global settings (which are
produced by `configure` before considering flavours), so a build system
rule was used to pass -DDYNAMIC_BY_DEFAULT to the C compiler so that
deriveConstants could infer it.

* Make build system has it disabled for 8 years (951e28c0)
* It has never been implemented in Hadrian
* Last time someone tried to enable it 1 year ago it didn't work (!2436)
* Having this as a global constant impedes making GHC multi-target (see !5427)

This commit fully removes support for dynamic-by-default. If someone
wants to reimplement something like this, it would probably need to move
the logic in the compiler.

(Doing this would probably need some refactoring of the way the compiler
handles DynFlags: DynFlags are used to store and to pass enabled ways to
many parts of the compiler. It can be set by command-line flags, GHC
API, global settings. In multi-target GHC, we will use DynFlags to load
the target platform and its constants: but at this point with the
current DynFlags implementation we can't easily update the existing
DynFlags with target-specific options such as dynamic-by-default without
overriding ways previously set by the user.)

Matthew Pickering authored Apr 01, 2021 and Marge Bot committed Apr 07, 2021

Workaround for #19624