Gradual migration of operator 'mod' to 'rem'

- Introduce new 'rem' operator convention
 - Prefer 'rem()' to 'mod()' when both are available, even if mod() is a
   member, and rem() -- an extension
 - Place operator 'rem' under the language feature

compiler/testData/codegen/box/operatorConventions/remAssignmentOperation.kt

@@ -0,0 +1,17 @@
+class A() {
+    var x = 5
+}
+
+operator fun A.modAssign(y: Int) { throw RuntimeException("mod has been called instead of rem") }
+operator fun A.remAssign(y: Int) { x %= y + 1 }
+
+fun box(): String {
+    val original = A()
+    val a = original
+
+    a %= 2
+    if (a !== original) return "Fail 1: $a !== $original"
+    if (a.x != 2) return "Fail 2: ${a.x} != 2"
+
+    return "OK"
+}

compiler/testData/codegen/box/operatorConventions/remOverModOperation.kt

@@ -0,0 +1,18 @@
+class A() {
+    var x = 5
+
+    operator fun mod(y: Int) { throw RuntimeException("mod has been called instead of rem") }
+    operator fun rem(y: Int) { x -= y }
+}
+
+fun box(): String {
+    val a = A()
+
+    a % 5
+
+    if (a.x != 0) {
+        return "Fail: a.x(${a.x}) != 0"
+    }
+
+    return "OK"
+}

compiler/testData/codegen/light-analysis/operatorConventions/remAssignmentOperation.txt

@@ -0,0 +1,13 @@
+public final class A {
+    private field x: int
+    public method <init>(): void
+    public final method getX(): int
+    public final method setX(p0: int): void
+}
+
+
+public final class RemAssignmentOperationKt {
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+    public final static method modAssign(@org.jetbrains.annotations.NotNull p0: A, p1: int): void
+    public final static method remAssign(@org.jetbrains.annotations.NotNull p0: A, p1: int): void
+}

compiler/testData/codegen/light-analysis/operatorConventions/remOverModOperation.txt

@@ -0,0 +1,13 @@
+public final class A {
+    private field x: int
+    public method <init>(): void
+    public final method getX(): int
+    public final method mod(p0: int): void
+    public final method rem(p0: int): void
+    public final method setX(p0: int): void
+}
+
+
+public final class RemOverModOperationKt {
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+}

compiler/testData/diagnostics/tests/DeprecatedModAssignOperatorConventions.kt

@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class OldAndNew {
+    operator fun modAssign(x: Int) {}
+    operator fun remAssign(x: Int) {}
+}
+
+class OnlyOld {
+    operator fun modAssign(x: Int) {}
+}
+
+class OnlyNew {
+    operator fun remAssign(x: Int) {}
+}
+
+class Sample
+
+operator fun Sample.modAssign(x: Int) {}
+operator fun Sample.remAssign(x: Int) {}
+
+class ModAndRemAssign {
+    operator fun mod(x: Int): ModAndRemAssign = ModAndRemAssign()
+    operator fun remAssign(x: Int) {}
+}
+
+fun test() {
+    val oldAndNew = OldAndNew()
+    oldAndNew %= 1
+
+    val onlyOld = OnlyOld()
+    onlyOld %= 1
+
+    val onlyNew = OnlyNew()
+    onlyNew %= 1
+
+    val sample = Sample()
+    sample %= 1
+
+    var modAndRemAssign = ModAndRemAssign()
+    modAndRemAssign <!ASSIGN_OPERATOR_AMBIGUITY!>%=<!> 1
+}

compiler/testData/diagnostics/tests/DeprecatedModAssignOperatorConventions.txt

@@ -0,0 +1,46 @@
+package
+
+public fun test(): kotlin.Unit
+public operator fun Sample.modAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+public operator fun Sample.remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+
+public final class ModAndRemAssign {
+    public constructor ModAndRemAssign()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): ModAndRemAssign
+    public final operator fun remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OldAndNew {
+    public constructor OldAndNew()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun modAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public final operator fun remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OnlyNew {
+    public constructor OnlyNew()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OnlyOld {
+    public constructor OnlyOld()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun modAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Sample {
+    public constructor Sample()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/DeprecatedModOperatorConventions.kt

@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class OldAndNew {
+    operator fun mod(x: Int) {}
+    operator fun rem(x: Int) {}
+}
+
+class OnlyOld {
+    operator fun mod(x: Int) {}
+}
+
+class OnlyNew {
+    operator fun rem(x: Int) {}
+}
+
+class Sample
+
+operator fun Sample.mod(x: Int) {}
+operator fun Sample.rem(x: Int) {}
+
+class IntAndUnit {
+    operator fun mod(x: Int): Int = 0
+    operator fun rem(x: Int) {}
+}
+
+fun test() {
+    OldAndNew() % 1
+    OnlyOld() % 1
+    OnlyNew() % 1
+    Sample() % 1
+
+    takeInt(<!TYPE_MISMATCH!>IntAndUnit() % 1<!>)
+}
+
+fun takeInt(x: Int) {}

compiler/testData/diagnostics/tests/DeprecatedModOperatorConventions.txt

@@ -0,0 +1,47 @@
+package
+
+public fun takeInt(/*0*/ x: kotlin.Int): kotlin.Unit
+public fun test(): kotlin.Unit
+public operator fun Sample.mod(/*0*/ x: kotlin.Int): kotlin.Unit
+public operator fun Sample.rem(/*0*/ x: kotlin.Int): kotlin.Unit
+
+public final class IntAndUnit {
+    public constructor IntAndUnit()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): kotlin.Int
+    public final operator fun rem(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OldAndNew {
+    public constructor OldAndNew()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): kotlin.Unit
+    public final operator fun rem(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OnlyNew {
+    public constructor OnlyNew()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun rem(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class OnlyOld {
+    public constructor OnlyOld()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Sample {
+    public constructor Sample()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/operatorRem/noOperatorRemFeature.kt

@@ -0,0 +1,16 @@
+// !LANGUAGE: -OperatorRem
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class Foo {
+    <!UNSUPPORTED_FEATURE!>operator<!> fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    <!UNSUPPORTED_FEATURE!>operator<!> fun remAssign(x: Int) {}
+}
+
+fun baz() {
+    val f = Foo() % 1
+    val b = Bar()
+    b %= 1
+}

compiler/testData/diagnostics/tests/operatorRem/noOperatorRemFeature.txt

@@ -0,0 +1,19 @@
+package
+
+public fun baz(): kotlin.Unit
+
+public final class Bar {
+    public constructor Bar()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun rem(/*0*/ x: kotlin.Int): Foo
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/operatorRem/operatorRem.kt

@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class Foo {
+    operator fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    operator fun remAssign(x: Int) {}
+}
+
+fun baz() {
+    val f = Foo() % 1
+    val b = Bar()
+    b %= 1
+}

compiler/testData/diagnostics/tests/operatorRem/operatorRem.txt

@@ -0,0 +1,19 @@
+package
+
+public fun baz(): kotlin.Unit
+
+public final class Bar {
+    public constructor Bar()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun remAssign(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun rem(/*0*/ x: kotlin.Int): Foo
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/operatorRem/preferRemAsExtentionOverMod.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+}
+operator fun Foo.mod(x: Int): Foo = Foo()
+operator fun Foo.rem(x: Int): Int = 0
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}

compiler/testData/diagnostics/tests/operatorRem/preferRemAsExtentionOverMod.txt

@@ -0,0 +1,13 @@
+package
+
+public fun foo(): kotlin.Unit
+public fun takeInt(/*0*/ x: kotlin.Int): kotlin.Unit
+public operator fun Foo.mod(/*0*/ x: kotlin.Int): Foo
+public operator fun Foo.rem(/*0*/ x: kotlin.Int): kotlin.Int
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/operatorRem/preferRemAsMemberOverMod.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    operator fun mod(x: Int): Foo = Foo()
+    operator fun rem(x: Int): Int = 0
+}
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}

compiler/testData/diagnostics/tests/operatorRem/preferRemAsMemberOverMod.txt

@@ -0,0 +1,13 @@
+package
+
+public fun foo(): kotlin.Unit
+public fun takeInt(/*0*/ x: kotlin.Int): kotlin.Unit
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): Foo
+    public final operator fun rem(/*0*/ x: kotlin.Int): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/operatorRem/prefereRemAsExtensionOverMemberMod.kt

@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    operator fun mod(x: Int): Foo = Foo()
+}
+
+operator fun Foo.rem(x: Int): Int = 0
+
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}

compiler/testData/diagnostics/tests/operatorRem/prefereRemAsExtensionOverMemberMod.txt

@@ -0,0 +1,13 @@
+package
+
+public fun foo(): kotlin.Unit
+public fun takeInt(/*0*/ x: kotlin.Int): kotlin.Unit
+public operator fun Foo.rem(/*0*/ x: kotlin.Int): kotlin.Int
+
+public final class Foo {
+    public constructor Foo()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun mod(/*0*/ x: kotlin.Int): Foo
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}