[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 7 commits: ghci: Mention active language edition in startup banner
Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC
Commits:
427fbe14 by Adam Gundry at 2026-03-18T12:26:54-04:00
ghci: Mention active language edition in startup banner
Per GHC proposal 632, this makes the GHCi startup banner include
the active language edition, plus an indication of whether this
was the default (as opposed to being explicitly selected via an
option such as `-XGHC2024`). For example:
```
$ ghci
GHCi, version 9.14.1: https://www.haskell.org/ghc/ :? for help
Using default language edition: GHC2024
ghci>
```
Fixes #26037.
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a0f0904f by sheaf at 2026-03-18T12:27:02-04:00
Improve incomplete record selector warnings
This commit stops GHC from emitting spurious incomplete record selector
warnings for bare selectors/projections such as .fld
There are two places we currently emit incomplete record selector
warnings:
1. In the desugarer, when we see a record selector or an occurrence
of 'getField'. Here, we can use pattern matching information to
ensure we don't give false positives.
2. In the typechecker, which might sometimes give false positives but
can emit warnings in cases that the pattern match checker would
otherwise miss.
This is explained in Note [Detecting incomplete record selectors]
in GHC.HsToCore.Pmc.
Now, we obviously don't want to emit the same error twice, and generally
we prefer (1), as those messages contain fewer false positives. So we
suppress (2) when we are sure we are going to emit (1); the logic for
doing so is in GHC.Tc.Instance.Class.warnIncompleteRecSel,
and works by looking at the CtOrigin.
Now, the issue was that this logic handled explicit record selectors as
well as overloaded record field selectors such as "x.r" (which turns
into a simple GetFieldOrigin CtOrigin), but it didn't properly handle
record projectors like ".fld" or ".fld1.fld2" (which result in other
CtOrigins such as 'RecordFieldProjectionOrigin').
To solve this problem, we re-use the 'isHasFieldOrigin' introduced in
fbdc623a (slightly adjusted).
On the way, we also had to update the desugarer with special handling
for the 'ExpandedThingTc' case in 'ds_app', to make sure that
'ds_app_var' sees all the type arguments to 'getField' in order for it
to indeed emit warnings like in (1).
Fixes #26686
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35093c67 by Cheng Shao at 2026-03-18T12:27:04-04:00
rts: opportunistically grow the MutableByteArray# in-place in resizeMutableByteArray#
Following !15234, this patch improves `resizeMutableByteArray#` memory
efficiency by growing the `MutableByteArray#` in-place if possible,
addressing an old todo comment here. Also adds a new test case
`resizeMutableByteArrayInPlace` that stresses this behavior.
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c93b0ca5 by Matthew Craven at 2026-03-18T12:27:10-04:00
Change representation of floating point literals
This commit changes the representation of floating point literals
throughough the compiler, in particular in Core and Cmm.
The Rational type is deficient for this purpose, dealing poorly
with NaN, +/-Infinity, and negative zero. Instead, the new module
GHC.Types.Literal.Floating uses the host Float/Double type to represent
NaNs, infinities and negative zero. It also contains a Rational
constructor, for the benefit of -fexcess-precision.
Other changes:
- Remove Note [negative zero] and related code
This also removes the restrictions on constant-folding of division
by zero, and should make any problems with NaN/Infinity more obvious.
- Use -0.0 as the additive identity for Core constant folding rules
for floating-point addition, fixing #21227.
- Manual worker-wrapper for GHC.Float.rationalToDouble. This is
intended to prevent the compiler's WW on this function from
interfering with constant-folding. This change means that we now
avoid allocating a box for the result of a 'realToFrac' call in
T10359.
- Combine floatDecodeOp and doubleDecodeOp.
This change also fixes a bug in doubleDecodeOp wherein it
would incorrectly produce an Int# instead of an Int64#
literal for the mantissa component with 64-bit targets.
- Use Float/Double for assembly immediates, and update the X86 and
PowerPC backends to properly handle special values such as NaN and
infinity.
- Allow 'rational_to' to handle zero denominators, fixing a
TODO in GHC.Core.Opt.ConstantFold.
Fixes #8364 #9811 #18897 #21227
Progress towards #26919
Metric Decrease:
T10359
Co-authored-by: sheaf
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