Relax rules related to noinline/crossinline/reified in header/impl functions

See the comments in KT-18752 for the current resolution

 #KT-15377 Fixed
 #KT-18752 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/HeaderImplDeclarationChecker.kt

@@ -292,7 +292,9 @@ object HeaderImplDeclarationChecker : DeclarationChecker {
             object TypeParameterNames : Incompatible("names of type parameters are different")
 
             object ValueParameterHasDefault : Incompatible("some parameters have default values")
-            object ValueParameterModifiers : Incompatible("parameter modifiers are different (vararg, coroutine, crossinline, noinline)")
+            object ValueParameterVararg : Incompatible("some value parameter is vararg in one declaration and non-vararg in the other")
+            object ValueParameterNoinline : Incompatible("some value parameter is noinline in one declaration and not noinline in the other")
+            object ValueParameterCrossinline : Incompatible("some value parameter is crossinline in one declaration and not crossinline in the other")
 
             // Functions
 
@@ -376,7 +378,13 @@ object HeaderImplDeclarationChecker : DeclarationChecker {
         areCompatibleTypeParameters(aTypeParams, bTypeParams, platformModule, substitutor).let { if (it != Compatible) return it }
 
         if (!equalsBy(aParams, bParams, ValueParameterDescriptor::declaresDefaultValue)) return Incompatible.ValueParameterHasDefault
-        if (!equalsBy(aParams, bParams, { p -> listOf(p.varargElementType != null, p.isCrossinline, p.isNoinline) })) return Incompatible.ValueParameterModifiers
+        if (!equalsBy(aParams, bParams, { p -> listOf(p.varargElementType != null) })) return Incompatible.ValueParameterVararg
+
+        // Adding noinline/crossinline to parameters is disallowed, except if the header declaration was not inline at all
+        if (a is FunctionDescriptor && a.isInline) {
+            if (aParams.indices.any { i -> !aParams[i].isNoinline && bParams[i].isNoinline }) return Incompatible.ValueParameterNoinline
+            if (aParams.indices.any { i -> !aParams[i].isCrossinline && bParams[i].isCrossinline }) return Incompatible.ValueParameterCrossinline
+        }
 
         when {
             a is FunctionDescriptor && b is FunctionDescriptor -> areCompatibleFunctions(a, b).let { if (it != Compatible) return it }
@@ -443,7 +451,9 @@ object HeaderImplDeclarationChecker : DeclarationChecker {
         if (!areCompatibleTypeLists(a.map { substitutor(it.defaultType) }, b.map { it.defaultType }, platformModule))
             return Incompatible.TypeParameterUpperBounds
         if (!equalsBy(a, b, TypeParameterDescriptor::getVariance)) return Incompatible.TypeParameterVariance
-        if (!equalsBy(a, b, TypeParameterDescriptor::isReified)) return Incompatible.TypeParameterReified
+
+        // Removing "reified" from a header function's type parameter is fine
+        if (a.indices.any { i -> !a[i].isReified && b[i].isReified }) return Incompatible.TypeParameterReified
 
         return Compatible
     }

compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.kt

@@ -0,0 +1,27 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// MODULE: m1-common
+// FILE: common.kt
+
+header fun f1(s: () -> String)
+header inline fun f2(s: () -> String)
+header inline fun f3(noinline s: () -> String)
+
+header fun f4(s: () -> String)
+header inline fun f5(s: () -> String)
+header inline fun f6(crossinline s: () -> String)
+
+header fun f7(x: Any)
+header fun f8(vararg x: Any)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+impl inline fun f1(noinline s: () -> String) {}
+<!IMPLEMENTATION_WITHOUT_HEADER!>impl inline fun f2(noinline s: () -> String)<!> {}
+impl inline fun f3(s: () -> String) {}
+impl inline fun f4(crossinline s: () -> String) {}
+<!IMPLEMENTATION_WITHOUT_HEADER!>impl inline fun f5(crossinline s: () -> String)<!> {}
+impl inline fun f6(s: () -> String) {}
+<!IMPLEMENTATION_WITHOUT_HEADER!>impl fun f7(vararg x: Any)<!> {}
+<!IMPLEMENTATION_WITHOUT_HEADER!>impl fun f8(x: Any)<!> {}

compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.txt

@@ -0,0 +1,24 @@
+// -- Module: <m1-common> --
+package
+
+public header fun f1(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public header inline fun f2(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public header inline fun f3(/*0*/ noinline s: () -> kotlin.String): kotlin.Unit
+public header fun f4(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public header inline fun f5(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public header inline fun f6(/*0*/ crossinline s: () -> kotlin.String): kotlin.Unit
+public header fun f7(/*0*/ x: kotlin.Any): kotlin.Unit
+public header fun f8(/*0*/ vararg x: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+
+
+// -- Module: <m2-jvm> --
+package
+
+public impl inline fun f1(/*0*/ noinline s: () -> kotlin.String): kotlin.Unit
+public impl inline fun f2(/*0*/ noinline s: () -> kotlin.String): kotlin.Unit
+public impl inline fun f3(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public impl inline fun f4(/*0*/ crossinline s: () -> kotlin.String): kotlin.Unit
+public impl inline fun f5(/*0*/ crossinline s: () -> kotlin.String): kotlin.Unit
+public impl inline fun f6(/*0*/ s: () -> kotlin.String): kotlin.Unit
+public impl fun f7(/*0*/ vararg x: kotlin.Any /*kotlin.Array<out kotlin.Any>*/): kotlin.Unit
+public impl fun f8(/*0*/ x: kotlin.Any): kotlin.Unit

compiler/testData/multiplatform/incompatibleCallables/common.kt

@@ -1,5 +1,3 @@
-import kotlin.coroutines.experimental.*
-
 header fun f1()
 
 header fun f2(name: String)
@@ -21,7 +19,7 @@ public header fun f10()
 
 header fun <T : Number> f11()
 header fun <U : MutableList<String>> f12()
-header fun <A, B : Continuation<A>> f13()
+header fun <A, B : Comparable<A>> f13()
 
 header inline fun <X> f14()
 header inline fun <reified Y> f15()
@@ -30,9 +28,7 @@ header fun f16(s: String)
 
 header fun f17(vararg s: String)
 header fun f18(s: Array<out String>)
-header inline fun f19(crossinline s: () -> Unit)
+header inline fun f19(s: () -> Unit)
 header inline fun f20(s: () -> Unit)
-header inline fun f21(noinline s: () -> Unit)
+header fun f21(c: suspend Unit.() -> Unit)
-header inline fun f22(s: () -> Unit)
+header fun f22(c: Unit.() -> Unit)
-header fun f23(c: suspend Unit.() -> Unit)
-header fun f24(c: Unit.() -> Unit)

compiler/testData/multiplatform/incompatibleCallables/jvm.kt

@@ -1,5 +1,3 @@
-import kotlin.coroutines.experimental.*
-
 impl fun f1(): String = ""
 
 impl fun f2(otherName: String) {}
@@ -21,7 +19,7 @@ private impl fun f10() {}
 
 impl fun <T : Annotation> f11() {}
 impl fun <U : MutableList<out String>> f12() {}
-impl fun <A, B : Continuation<B>> f13() {}
+impl fun <A, B : Comparable<B>> f13() {}
 
 impl inline fun <reified X> f14() {}
 impl inline fun <Y> f15() {}
@@ -30,9 +28,7 @@ impl fun f16(s: String = "") {}
 
 impl fun f17(s: Array<out String>) {}
 impl fun f18(vararg s: String) {}
-impl inline fun f19(s: () -> Unit) {}
+impl inline fun f19(crossinline s: () -> Unit) {}
-impl inline fun f20(crossinline s: () -> Unit) {}
+impl inline fun f20(noinline s: () -> Unit) {}
-impl inline fun f21(s: () -> Unit) {}
+impl fun f21(c: Unit.() -> Unit) {}
-impl inline fun f22(noinline s: () -> Unit) {}
+impl fun f22(c: suspend Unit.() -> Unit) {}
-impl fun f23(c: Unit.() -> Unit) {}
-impl fun f24(c: suspend Unit.() -> Unit) {}

compiler/testData/multiplatform/incompatibleCallables/output.txt

@@ -1,145 +1,124 @@
 -- Common --
-Exit code: COMPILATION_ERROR
+Exit code: OK
 Output:
-compiler/testData/multiplatform/incompatibleCallables/common.kt:1:15: error: unresolved reference: coroutines
+compiler/testData/multiplatform/incompatibleCallables/common.kt:33:19: warning: the feature "coroutines" is experimental (see: https://kotlinlang.org/docs/diagnostics/experimental-coroutines)
-import kotlin.coroutines.experimental.*
+header fun f21(c: suspend Unit.() -> Unit)
-              ^
+                  ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:24:20: error: unresolved reference: Continuation
-header fun <A, B : Continuation<A>> f13()
-                   ^
 
 -- JVM --
 Exit code: COMPILATION_ERROR
 Output:
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:3:1: error: 'impl' function 'f1' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:1:1: error: 'impl' function 'f1' has no corresponding 'header' declaration
 The following declaration is incompatible because return type is different:
     public header fun f1(): Unit
 
 impl fun f1(): String = ""
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:5:1: error: 'impl' function 'f2' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:3:1: error: 'impl' function 'f2' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter names are different:
     public header fun f2(name: String): Unit
 
 impl fun f2(otherName: String) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:7:1: error: 'impl' function 'f3' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:5:1: error: 'impl' function 'f3' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter types are different:
     public header fun f3(name: String): Unit
 
 impl fun f3(name: Double) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:8:1: error: 'impl' function 'f3ext' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:6:1: error: 'impl' function 'f3ext' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter types are different:
     public header fun String.f3ext(): Unit
 
 impl fun Double.f3ext() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:10:1: error: 'impl' function 'f4' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:8:1: error: 'impl' function 'f4' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter shapes are different (extension vs non-extension):
     public header fun f4(name: String): Unit
 
 impl fun String.f4() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:12:1: error: 'impl' function 'f5' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:10:1: error: 'impl' function 'f5' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter shapes are different (extension vs non-extension):
     public header fun String.f5(): Unit
 
 impl fun f5(name: String) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:14:1: error: 'impl' function 'f6' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:12:1: error: 'impl' function 'f6' has no corresponding 'header' declaration
 The following declaration is incompatible because number of value parameters is different:
     public header fun f6(p1: String, p2: Int): Unit
 
 impl fun f6(p2: Int) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:16:1: error: 'impl' function 'f7' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:14:1: error: 'impl' function 'f7' has no corresponding 'header' declaration
 The following declaration is incompatible because number of type parameters is different:
     public header fun <T> f7(): Unit
 
 impl fun <K, V> f7() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:18:1: error: 'impl' function 'f8' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:16:1: error: 'impl' function 'f8' has no corresponding 'header' declaration
 The following declaration is incompatible because visibility is different:
     internal header fun f8(): Unit
 
 public impl fun f8() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:19:1: error: 'impl' function 'f9' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:17:1: error: 'impl' function 'f9' has no corresponding 'header' declaration
 The following declaration is incompatible because visibility is different:
     private header fun f9(): Unit
 
 internal impl fun f9() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:20:1: error: 'impl' function 'f10' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:18:1: error: 'impl' function 'f10' has no corresponding 'header' declaration
 The following declaration is incompatible because visibility is different:
     public header fun f10(): Unit
 
 private impl fun f10() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:26:1: error: 'impl' function 'f14' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:24:1: error: 'impl' function 'f14' has no corresponding 'header' declaration
 The following declaration is incompatible because some type parameter is reified in one declaration and non-reified in the other:
     public header inline fun <X> f14(): Unit
 
 impl inline fun <reified X> f14() {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:27:1: error: 'impl' function 'f15' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:27:1: error: 'impl' function 'f16' has no corresponding 'header' declaration
-The following declaration is incompatible because some type parameter is reified in one declaration and non-reified in the other:
-    public header inline fun <reified Y> f15(): Unit
-
-impl inline fun <Y> f15() {}
-^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:29:1: error: 'impl' function 'f16' has no corresponding 'header' declaration
 The following declaration is incompatible because some parameters have default values:
     public header fun f16(s: String): Unit
 
 impl fun f16(s: String = "") {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:31:1: error: 'impl' function 'f17' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:29:1: error: 'impl' function 'f17' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
+The following declaration is incompatible because some value parameter is vararg in one declaration and non-vararg in the other:
     public header fun f17(vararg s: String): Unit
 
 impl fun f17(s: Array<out String>) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:32:1: error: 'impl' function 'f18' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:30:1: error: 'impl' function 'f18' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
+The following declaration is incompatible because some value parameter is vararg in one declaration and non-vararg in the other:
     public header fun f18(s: Array<out String>): Unit
 
 impl fun f18(vararg s: String) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:33:1: error: 'impl' function 'f19' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:31:1: error: 'impl' function 'f19' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
+The following declaration is incompatible because some value parameter is crossinline in one declaration and not crossinline in the other:
-    public header inline fun f19(crossinline s: () -> Unit): Unit
+    public header inline fun f19(s: () -> Unit): Unit
 
-impl inline fun f19(s: () -> Unit) {}
+impl inline fun f19(crossinline s: () -> Unit) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:34:1: error: 'impl' function 'f20' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:32:1: error: 'impl' function 'f20' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
+The following declaration is incompatible because some value parameter is noinline in one declaration and not noinline in the other:
     public header inline fun f20(s: () -> Unit): Unit
 
-impl inline fun f20(crossinline s: () -> Unit) {}
+impl inline fun f20(noinline s: () -> Unit) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:35:1: error: 'impl' function 'f21' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:33:1: error: 'impl' function 'f21' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
-    public header inline fun f21(noinline s: () -> Unit): Unit
-
-impl inline fun f21(s: () -> Unit) {}
-^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:36:1: error: 'impl' function 'f22' has no corresponding 'header' declaration
-The following declaration is incompatible because parameter modifiers are different (vararg, coroutine, crossinline, noinline):
-    public header inline fun f22(s: () -> Unit): Unit
-
-impl inline fun f22(noinline s: () -> Unit) {}
-^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:37:1: error: 'impl' function 'f23' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter types are different:
-    public header fun f23(c: suspend Unit.() -> Unit): Unit
+    public header fun f21(c: suspend Unit.() -> Unit): Unit
 
-impl fun f23(c: Unit.() -> Unit) {}
+impl fun f21(c: Unit.() -> Unit) {}
 ^
-compiler/testData/multiplatform/incompatibleCallables/jvm.kt:38:1: error: 'impl' function 'f24' has no corresponding 'header' declaration
+compiler/testData/multiplatform/incompatibleCallables/jvm.kt:34:1: error: 'impl' function 'f22' has no corresponding 'header' declaration
 The following declaration is incompatible because parameter types are different:
-    public header fun f24(c: Unit.() -> Unit): Unit
+    public header fun f22(c: Unit.() -> Unit): Unit
 
-impl fun f24(c: suspend Unit.() -> Unit) {}
+impl fun f22(c: suspend Unit.() -> Unit) {}
 ^

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -13907,6 +13907,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/topLevelFun/simpleHeaderFun.kt");
                     doTest(fileName);
                 }
+
+                @TestMetadata("valueParameterModifiers.kt")
+                public void testValueParameterModifiers() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.kt");
+                    doTest(fileName);
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/multiplatform/topLevelProperty")