Delete products of previous analysis when dropping previous analysis

[Friendseeker]

This PR fixes #1234, sbt/sbt#2074, #825

Issue

prevAnalysis in IncrementalCompilerImpl.scala drops previous analysis when setup is changed.

However, it kept all products of previous analysis, hence these stale products never gets removed.

Fix

When the previous analysis is dropped, delete all products of previous analysis.

Validating the fix

Followed https://github.com/jackkoenig/zinc-bug-example with custom zinc build containing the fix.

❯ git status 
On branch main
Your branch is ahead of 'origin/main' by 1 commit.
  (use "git push" to publish your local commits)

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	.java-version

nothing added to commit but untracked files present (use "git add" to track)

~/zinc-bug-example-2/zinc-bug-example main* ⇡
❯ jenv local 19.0

~/zinc-bug-example-2/zinc-bug-example main* ⇡
❯ sbt compile
[info] welcome to sbt 1.9.7 (Oracle Corporation Java 19.0.1)
[info] loading global plugins from /Users/jiahuitan/.sbt/1.0/plugins
[info] loading project definition from /Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/project
[info] loading settings for project root from build.sbt ...
[info] set current project to zinc-bug-example (in build file:/Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/)
[info] Executing in batch mode. For better performance use sbt's shell
[info] compiling 4 Scala sources to /Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/target/scala-2.13/classes ...
[success] Total time: 2 s, completed Nov 30, 2023, 4:24:54 p.m.

~/zinc-bug-example-2/zinc-bug-example main* ⇡
❯ jenv local 21.0

~/zinc-bug-example-2/zinc-bug-example main* ⇡
❯ git apply moveB.diff

~/zinc-bug-example-2/zinc-bug-example main* ⇡
❯ sbt compile
[info] welcome to sbt 1.9.7 (Oracle Corporation Java 21.0.1)
[info] loading global plugins from /Users/jiahuitan/.sbt/1.0/plugins
[info] loading project definition from /Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/project
[info] loading settings for project root from build.sbt ...
[info] set current project to zinc-bug-example (in build file:/Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/)
[info] Executing in batch mode. For better performance use sbt's shell
[info] compiling 4 Scala sources to /Users/jiahuitan/zinc-bug-example-2/zinc-bug-example/target/scala-2.13/classes ...
[success] Total time: 2 s, completed Nov 30, 2023, 4:25:28 p.m.

Credit to

• @jackkoenig for providing reproduction & pinpointing exact cause of the problem
• @armanbilge for guiding me to setup custom zinc build

[eed3si9n]

Thanks!