[K/N] Extract C header generation to a separate phase

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/CExport.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.backend.konan.driver.phases
 
+import org.jetbrains.kotlin.backend.konan.NativeGenerationState
+import org.jetbrains.kotlin.backend.konan.cexport.CAdapterApiExporter
 import org.jetbrains.kotlin.backend.konan.cexport.CAdapterExportedElements
 import org.jetbrains.kotlin.backend.konan.cexport.CAdapterGenerator
 import org.jetbrains.kotlin.backend.konan.cexport.CAdapterTypeTranslator
@@ -17,3 +19,10 @@ internal val BuildCExports = createSimpleNamedCompilerPhase<PsiToIrContext, Fron
     val typeTranslator = CAdapterTypeTranslator(prefix, context.builtIns)
     CAdapterGenerator(context, typeTranslator).buildExports(input.moduleDescriptor)
 }
+
+internal val CExportGenerateApiPhase = createSimpleNamedCompilerPhase<NativeGenerationState, Unit>(
+        name = "CExportGenerateApi",
+        description = "Create C header for the exported API",
+) { context, _ ->
+    CAdapterApiExporter(context, context.context.cAdapterExportedElements!!).makeGlobalStruct()
+}

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/TopLevelPhases.kt

@@ -173,10 +173,14 @@ internal fun PhaseEngine<NativeGenerationState>.runBackendCodegen(module: IrModu
     }
     mergeDependencies(module, dependenciesToCompile)
     runCodegen(module)
+    if (context.config.produce.isNativeLibrary) {
+        runPhase(CExportGenerateApiPhase)
+    }
     runPhase(CStubsPhase)
     // TODO: Consider extracting llvmModule and friends from nativeGenerationState and pass them explicitly.
     //  Motivation: possibility to run LTO on bitcode level after separate IR compilation.
     val llvmModule = context.llvm.module
+    // TODO: Consider dropping these in favor of proper phases dumping and validation.
     if (context.config.needCompilerVerification || context.config.configuration.getBoolean(KonanConfigKeys.VERIFY_BITCODE)) {
         runPhase(VerifyBitcodePhase, llvmModule)
     }

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/IrToBitcode.kt

@@ -347,8 +347,6 @@ internal class CodeGeneratorVisitor(
     }
     private fun appendCAdapters(elements: CAdapterExportedElements) {
         CAdapterCodegen(codegen, generationState).buildAllAdaptersRecursively(elements)
-        // TODO: It is not a part of IrToBitcode. Maybe move it somewhere?
-        CAdapterApiExporter(generationState, elements).makeGlobalStruct()
     }
 
     private fun FunctionGenerationContext.initThreadLocalField(irField: IrField) {