Missing `IsString` instance with debug flags enabled

[kleinreact]

Missing `IsString` instance with debug flags enabled

[andreasabel]

@UlfNorell : This issue points at gaps in our build matrix. Could you please add a configuration that would have exposed this issue?

agda/src/github/workflows/cabal.yml

Lines 58 to 83 in a445e3b

	include:
	## Latest GHC, special builds
	# Linux, without tests but with doctest
	- os: ubuntu-22.04
	description: Linux doctest
	ghc-ver: '9.8.1'
	# Can't leave cabal-flags empty here lest it becomes the default value.
	cabal-flags: '--disable-tests'
	doctest: true
	# Linux, without -f enable-cluster-counting but with -f debug
	- os: ubuntu-22.04
	description: Linux debug
	ghc-ver: '9.8.1'
	cabal-flags: '--enable-tests -f debug'
	# Linux, with containers-0.7 and everything
	- os: ubuntu-22.04
	description: Linux containers 0.7
	ghc-ver: '9.8.1'
	## Andreas, 2023-09-28: Test containers-0.7 here which has breaking changes.
	## Note: -c 'containers >= 0.7' with single quotes does not get communicated properly.
	## (The single quotes stay, and "-c 'containers" is an option parse error for cabal.)
	cabal-flags: |
	--enable-tests -f enable-cluster-counting -f debug -c containers>=0.7 --allow-newer=containers

[UlfNorell]

I'll leave that to someone more familiar with the CI system. The test to add is compiling with all the debug flags turned on (-fdebug -fdebug-parsing -fdebug-serialisation).

[andreasabel]

I'll leave that to someone more familiar with the CI system.

Could be your entry point into CI...

I just realized that the released 2.6.4.1 has this build problem while working on relaxing its ansi-terminal constraint.
I guess this calls for a patch release 2.6.4.2.

[UlfNorell]

I wouldn't worry too much about this particular issue. -fdebug-parsing and -fdebug-serialisation are extremely niche flags that you only turn on if you are working on the operator parser or serialiser, and in that case you can fix any problems as you find them. I would argue it's not worth spending CI time or effort pushing out a hotfix release for this.

[andreasabel]

I don't want the latest release to have broken build paths.