`dub lint` should only build dscanner if dscanner source code has changed

[Moth-Tolias]

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System information

• dub version: v1.29.0
• OS Platform and distribution: Windows 8
• compiler version v2.100.0-dirty

Bug Description

dub lint always builds dscanner anew on every invocation even if a prior up-to-date build exists, wasting several seconds and causing unnecessary log spam.

How to reproduce

1. run dub lint
2. observe that an entirely new build of dscanner is performed, regardless of previous invocations.

Expected Behavior

if an up-to-date build of dscanner already exists, dub lint should use that.

Logs

Running pre-generate commands for dscanner...
Performing "debug" build using C:\D\dmd2\windows\bin\dmd.exe for x86_64.
stdx-allocator 2.77.5: target for configuration "library" is up to date.
emsi_containers 0.8.1: target for configuration "library" is up to date.
libdparse 0.19.2: target for configuration "library" is up to date.
dsymbol 0.13.0: target for configuration "library" is up to date.
inifiled 1.3.3: target for configuration "library-quiet" is up to date.
libddoc:common 0.8.0: target for configuration "library" is up to date.
libddoc 0.8.0: target for configuration "lib" is up to date.
dscanner 0.12.1: building configuration "application"...
Linking...
dparse.lib(lexer.obj) : warning LNK4255: library contain multiple objects of the same name; linking object as if no debug info
To force a rebuild of up-to-date targets, run again with --force.
Running ../../../../AppData/Local/dub/packages/dscanner-0.12.1/dscanner/bin/dscanner.exe --styleCheck C:\Users\Su\Documents\src\libraries\expected\

[WebFreak001]

this is a bug with dscanner that it uses preGenerateCommands instead of preBuildCommands for the dub hash generation.

It should be fixed once https://github.com/dlang-community/D-Scanner/pull/857 is merged

[veelo]

Are you sure it does a full rebuild every time? On second invocation I "only" get:

Running pre-generate commands for dscanner...
Performing "debug" build using C:\D\dmd2\windows\bin\dmd.exe for x86_64.
stdx-allocator 2.77.5: target for configuration "library" is up to date.
emsi_containers 0.8.1: target for configuration "library" is up to date.
libdparse 0.19.2: target for configuration "library" is up to date.
dsymbol 0.13.0: target for configuration "library" is up to date.
inifiled 1.3.3: target for configuration "library-quiet" is up to date.
libddoc:common 0.8.0: target for configuration "library" is up to date.
libddoc 0.8.0: target for configuration "lib" is up to date.
dscanner 0.12.1: target for configuration "application" is up to date.
To force a rebuild of up-to-date targets, run again with --force.

Still, it's spamming logs and doing unnecessary work. Implementing a --cached argument for dub run as suggested in https://github.com/dlang/dub/pull/2254#issuecomment-1153131950 would get rid of this.

[Moth-Tolias]

oh, that's curious. i always get a rebuild. i wonder what's different about our setups?

[veelo]

Curious indeed. I have a project where I call dub run dfmt repeatedly, and it recompiles every time as well, like you have with dscanner.