Add test

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -257,7 +257,7 @@ class CompilationTests {
     compileFilesInDir("tests/explicit-nulls/run", explicitNullsOptions)
   }.checkRuns()
 
-  // initialization tests
+  // initialization tests for global objects
   @Test def checkInitGlobal: Unit = {
     implicit val testGroup: TestGroup = TestGroup("checkInitGlobal")
     compileFilesInDir("tests/init-global/warn", defaultOptions.and("-Ysafe-init-global"), FileFilter.exclude(TestSources.negInitGlobalScala2LibraryTastyExcludelisted)).checkWarnings()
@@ -266,6 +266,20 @@ class CompilationTests {
       compileFilesInDir("tests/init-global/warn-tasty", defaultOptions.and("-Ysafe-init-global"), FileFilter.exclude(TestSources.negInitGlobalScala2LibraryTastyExcludelisted)).checkWarnings()
       compileFilesInDir("tests/init-global/pos-tasty", defaultOptions.and("-Ysafe-init-global", "-Werror"), FileFilter.exclude(TestSources.posInitGlobalScala2LibraryTastyExcludelisted)).checkCompile()
     end if
+
+    locally {
+      val group = TestGroup("checkInitGlobal/tastySource")
+      val tastSourceOptions = defaultOptions.and("-Ysafe-init-global")
+      val outDirLib = defaultOutputDir + group + "/A/tastySource/A"
+
+      // Set -sourceroot such that the source code cannot be found by the compiler
+      val libOptions = tastSourceOptions.and("-sourceroot", "tests/init-global/special/tastySource")
+      val lib = compileFile("tests/init-global/special/tastySource/A.scala", libOptions)(group).keepOutput.checkCompile()
+
+      compileFile("tests/init-global/special/tastySource/B.scala", tastSourceOptions.withClasspath(outDirLib))(group).checkWarnings()
+
+      lib.delete()
+    }
   }
 
   // initialization tests

tests/init-global/special/tastySource/A.scala

@@ -0,0 +1,4 @@
+object A:
+  def foo(fn: => Int) = bar(fn)
+
+  def bar(fn: => Int) = fn

tests/init-global/special/tastySource/B.check

@@ -0,0 +1,13 @@
+-- Warning: tests/init-global/special/tastySource/B.scala:4:14 ---------------------------------------------------------
+4 |  def bar = C.n * 3      // warn
+  |            ^^^
+  |Reading mutable state of object C during initialization of object B.
+  |Reading mutable state of other static objects is forbidden as it breaks initialization-time irrelevance. Calling trace:
+  |├── object B:	[ B.scala:1 ]
+  |│   ^
+  |├── A.scala:2
+  |├── A.scala:4
+  |├── var y = A.foo(bar) * 2	[ B.scala:2 ]
+  |│                 ^^^
+  |└── def bar = C.n * 3      // warn	[ B.scala:4 ]
+  |              ^^^

tests/init-global/special/tastySource/B.scala

@@ -0,0 +1,7 @@
+object B:
+  var y = A.foo(bar) * 2
+
+  def bar = C.n * 3      // warn
+
+object C:
+  var n = 10