[klib] Fix exception for clashing signatures from different modules

If we encounter a declaration in the current module whose signature
is the same as that of a declaration in another module which we happen
to also reference from the current module, don't report any errors,
just like we don't do it in Kotlin/JVM. This leaves the user in the KLIB
hell situation, but this is intentional, because otherwise a legitimate
change like moving a declaration to another module and marking
the original one as `@Deprecated("", level = DeprecationLevel.HIDDEN)`
would lead to a error, and we don't want that.

Also, don't try to show the diagnostics on a declaration that doesn't
have an IrFile.

^KT-65063 Fixed

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/linkage/SignatureClashDetector.kt

@@ -9,7 +9,8 @@ import org.jetbrains.kotlin.diagnostics.KtDiagnosticFactory1
 import org.jetbrains.kotlin.ir.IrDiagnosticReporter
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
-import org.jetbrains.kotlin.ir.util.file
+import org.jetbrains.kotlin.ir.util.fileOrNull
+import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.util.sourceElement
 import org.jetbrains.kotlin.utils.SmartSet
 
@@ -53,17 +54,34 @@ abstract class SignatureClashDetector<Signature : Any, Declaration : IrDeclarati
         }
     }
 
-    protected inline fun <Data : Any, ConflictingDeclaration : IrDeclaration> reportSignatureClashTo(
+    protected fun <Data : Any, ConflictingDeclaration : IrDeclaration> reportSignatureClashTo(
         diagnosticReporter: IrDiagnosticReporter,
         diagnosticFactory: KtDiagnosticFactory1<Data>,
         declarations: Collection<ConflictingDeclaration>,
         data: Data,
-        reportOnIfSynthetic: (ConflictingDeclaration) -> IrElement,
+        reportOnIfSynthetic: (ConflictingDeclaration) -> IrElement?,
     ) {
-        declarations.mapTo(LinkedHashSet()) { declaration ->
-            val reportOn = declaration.takeUnless { it.startOffset < 0 } ?: reportOnIfSynthetic(declaration)
-            diagnosticReporter.at(reportOn.sourceElement(), reportOn, declaration.file)
-        }.forEach {
+        val diagnostics = declarations.mapNotNullTo(LinkedHashSet()) { declaration ->
+            // Declarations that come from other modules may not have a file, so we don't show diagnostics on them.
+            val containingFile = declaration.fileOrNull ?: return@mapNotNullTo null
+            val reportOn = declaration.takeUnless { it.startOffset < 0 } ?: reportOnIfSynthetic(declaration) ?: return@mapNotNullTo null
+            diagnosticReporter.at(reportOn.sourceElement(), reportOn, containingFile)
+        }
+
+        assert(diagnostics.isEmpty() == declarations.isEmpty()) {
+            buildString {
+                append("Different declarations with the same signatures were detected, but no diagnostics will be reported ")
+                append("because none of those declarations have any source location info associated with them. ")
+                append("This could happen because the declarations came from an external module, or were generated by a compiler plugin. ")
+                appendLine("The following declarations have conflicting signatures:")
+                for (declaration in declarations) {
+                    append(" - ")
+                    appendLine(declaration.render())
+                }
+            }
+        }
+
+        diagnostics.forEach {
             it.report(diagnosticFactory, data)
         }
     }

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/diagnostics/IdSignatureClashDetector.kt

@@ -23,7 +23,7 @@ class IdSignatureClashDetector : SignatureClashDetector<IdSignature, IrDeclarati
             SerializationErrors.CONFLICTING_KLIB_SIGNATURES_ERROR,
             declarations,
             ConflictingKlibSignaturesData(signature, declarations),
-            reportOnIfSynthetic = { it.parentClassOrNull ?: it.file },
+            reportOnIfSynthetic = { it.parentClassOrNull },
         )
     }
 }

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/DeclarationTable.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.ir.IrBuiltIns
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.declarations.IrSymbolOwner
+import org.jetbrains.kotlin.ir.declarations.lazy.IrLazyDeclarationBase
 import org.jetbrains.kotlin.ir.util.IdSignature
 import org.jetbrains.kotlin.ir.util.KotlinMangler
 import org.jetbrains.kotlin.ir.util.render
@@ -25,14 +26,14 @@ abstract class GlobalDeclarationTable(private val mangler: KotlinMangler.IrMangl
     protected fun loadKnownBuiltins(builtIns: IrBuiltIns) {
         builtIns.knownBuiltins.forEach {
             val symbol = (it as IrSymbolOwner).symbol
-            table[it] = symbol.signature!!.also { id -> clashDetector.trackDeclaration(it, id) }
+            table[it] = symbol.signature!!.also { id -> clashDetector.trackDeclarationIfInCurrentModule(it, id) }
         }
     }
 
     open fun computeSignatureByDeclaration(declaration: IrDeclaration, compatibleMode: Boolean): IdSignature {
         return table.getOrPut(declaration) {
             publicIdSignatureComputer.composePublicIdSignature(declaration, compatibleMode).also {
-                clashDetector.trackDeclaration(declaration, it)
+                clashDetector.trackDeclarationIfInCurrentModule(declaration, it)
             }
         }
     }
@@ -40,6 +41,17 @@ abstract class GlobalDeclarationTable(private val mangler: KotlinMangler.IrMangl
     fun isExportedDeclaration(declaration: IrDeclaration, compatibleMode: Boolean): Boolean = with(mangler) { declaration.isExported(compatibleMode) }
 }
 
+private fun IdSignatureClashDetector.trackDeclarationIfInCurrentModule(declaration: IrDeclaration, signature: IdSignature) {
+    // Only count signature clashes on the declarations declared in the module being serialized.
+    // If there is a declaration in an external module with the same signature as some declaration in the current module,
+    // so be it (for now).
+    // Note that when we are serializing a module into a KLIB, the declarations from other modules always come in the form of Lazy IR,
+    // so this check is enough to ensure that this declaration is declared in the module currently being serialized.
+    if (declaration !is IrLazyDeclarationBase) {
+        trackDeclaration(declaration, signature)
+    }
+}
+
 open class DeclarationTable(globalTable: GlobalDeclarationTable) {
     protected val table = hashMapOf<IrDeclaration, IdSignature>()
     protected open val globalDeclarationTable: GlobalDeclarationTable = globalTable

compiler/testData/diagnostics/klibSerializationTests/signatureClash.diag.txt

@@ -1,14 +1,14 @@
-/foo.kt:7:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/foo.kt:13:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/main.kt:13:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/main.kt:19:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics
 
-/main.kt:16:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
+/main.kt:22:1: error: Platform declaration clash: The following declarations have the same KLIB signature (com.example.klib.serialization.diagnostics/foo|foo(){}[0]):
     fun foo(): kotlin.Long defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.String defined in com.example.klib.serialization.diagnostics
     fun foo(): kotlin.Int defined in com.example.klib.serialization.diagnostics

compiler/testData/diagnostics/klibSerializationTests/signatureClash.kt

@@ -1,6 +1,12 @@
 // FIR_IDENTICAL
 // RENDER_ALL_DIAGNOSTICS_FULL_TEXT
 
+// MODULE: lib
+package com.example.klib.serialization.diagnostics
+
+fun movedToLib() {}
+
+// MODULE: main(lib)
 // FILE: foo.kt
 package com.example.klib.serialization.diagnostics
 
@@ -15,6 +21,10 @@ fun foo(): String = ""<!>
 
 <!CONFLICTING_KLIB_SIGNATURES_ERROR!>fun foo(): Int = 0<!>
 
+@Deprecated("This function moved to the 'lib' module", level = DeprecationLevel.HIDDEN)
+fun movedToLib() {}
+
 fun main() {
     foo()
+    movedToLib()
 }

native/native.tests/testData/compilerOutput/SignatureClashDiagnostics/lib.kt

@@ -0,0 +1,3 @@
+package com.example.klib.serialization.diagnostics
+
+fun movedToLib() {}

native/native.tests/testData/compilerOutput/SignatureClashDiagnostics/main.kt

@@ -7,6 +7,10 @@ class A {
     fun foo(): Int = 0
 }
 
+@Deprecated("This function moved to the 'lib' module", level = DeprecationLevel.HIDDEN)
+fun movedToLib() {}
+
 fun main() {
     println(A().foo())
+    movedToLib()
 }

native/native.tests/tests/org/jetbrains/kotlin/konan/test/blackbox/CompilerOutputTest.kt

@@ -163,7 +163,8 @@ class FirCompilerOutputTest : CompilerOutputTestBase() {
         // TODO: use the Compiler Core test infrastructure for testing these diagnostics (KT-64393)
         val rootDir = File("native/native.tests/testData/compilerOutput/SignatureClashDiagnostics")
         val settings = testRunSettings
-        val compilationResult = compileLibrary(settings, rootDir.resolve("main.kt"))
+        val lib = compileLibrary(settings, rootDir.resolve("lib.kt")).assertSuccess().resultingArtifact
+        val compilationResult = compileLibrary(settings, rootDir.resolve("main.kt"), dependencies = listOf(lib))
         val goldenData = rootDir.resolve("output.txt")
 
         KotlinTestUtils.assertEqualsToFile(goldenData, compilationResult.toOutput())