Capitalize/decapitalize only ASCII characters across project

Use {de,}capitalizeAsciiOnly and to{Lower,Upper}CaseAsciiOnly where
possible, and stdlib's functions with Locale.US everywhere else.

Otherwise, if the default system locale is Turkish, the capital latin
letter "I" is transformed in toLowerCase to "ı" (see
https://github.com/JetBrains/kotlin/blob/66bc142f92085047a1ca64f9a291f0496e33dd98/libraries/stdlib/jvm/test/text/StringJVMTest.kt#L119),
which for example breaks the codegen for `intArrayOf` in
KT-25400/KT-43405.

Similarly, lower case latin letter "i" is transformed to "İ".

 #KT-13631 Fixed
 #KT-25400 Fixed
 #KT-43405 Fixed

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirJvmMangleComputer.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
 import org.jetbrains.kotlin.utils.addToStdlib.ifNotEmpty
 
 open class FirJvmMangleComputer(
@@ -210,7 +211,7 @@ open class FirJvmMangleComputer(
                             is ConeStarProjection -> appendSignature(MangleConstant.STAR_MARK)
                             is ConeKotlinTypeProjection -> {
                                 if (arg.kind != ProjectionKind.INVARIANT) {
-                                    appendSignature(arg.kind.name.toLowerCase())
+                                    appendSignature(arg.kind.name.toLowerCaseAsciiOnly())
                                     appendSignature(MangleConstant.VARIANCE_SEPARATOR)
                                 }
 

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/JavaUtils.kt

@@ -47,6 +47,7 @@ import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.Variance.*
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.capitalizeAsciiOnly
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 import java.lang.Deprecated
 import java.lang.annotation.Documented
@@ -140,7 +141,7 @@ internal fun JavaType?.toConeKotlinTypeWithoutEnhancement(
             val primitiveType = type
             val kotlinPrimitiveName = when (val javaName = primitiveType?.typeName?.asString()) {
                 null -> "Unit"
-                else -> javaName.capitalize()
+                else -> javaName.capitalizeAsciiOnly()
             }
 
             val classId = StandardClassIds.byName(kotlinPrimitiveName)
@@ -194,7 +195,7 @@ private fun JavaArrayType.toConeKotlinTypeWithoutEnhancement(
             )
         }
     } else {
-        val javaComponentName = componentType.type?.typeName?.asString()?.capitalize() ?: error("Array of voids")
+        val javaComponentName = componentType.type?.typeName?.asString()?.capitalizeAsciiOnly() ?: error("Array of voids")
         val classId = StandardClassIds.byName(javaComponentName + "Array")
 
         if (forAnnotationValueParameter) {

compiler/fir/jvm/src/org/jetbrains/kotlin/fir/resolve/FirJavaSyntheticNamesProvider.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.fir.NoMutableState
 import org.jetbrains.kotlin.fir.resolve.calls.FirSyntheticNamesProvider
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.capitalizeDecapitalize.capitalizeAsciiOnly
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.decapitalizeAsciiOnly
 import org.jetbrains.kotlin.util.capitalizeDecapitalize.toUpperCaseAsciiOnly
 
 @NoMutableState
@@ -91,7 +92,7 @@ object FirJavaSyntheticNamesProvider : FirSyntheticNamesProvider() {
             else -> return emptyList()
         }
         val withoutPrefix = identifier.removePrefix(prefix)
-        val withoutPrefixName = Name.identifier(withoutPrefix.decapitalize())
+        val withoutPrefixName = Name.identifier(withoutPrefix.decapitalizeAsciiOnly())
         return if (prefix == SETTER_PREFIX) {
             listOf(withoutPrefixName, Name.identifier(IS_PREFIX + withoutPrefix))
         } else {
@@ -99,4 +100,3 @@ object FirJavaSyntheticNamesProvider : FirSyntheticNamesProvider() {
         }
     }
 }
-

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirVisitorVoid
 import org.jetbrains.kotlin.name.SpecialNames
 import org.jetbrains.kotlin.types.Variance
+import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
 import org.jetbrains.kotlin.utils.Printer
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
@@ -226,7 +227,7 @@ class FirRenderer(builder: StringBuilder, private val mode: RenderMode = RenderM
     }
 
     private fun FirMemberDeclaration.modalityAsString(): String {
-        return modality?.name?.toLowerCase() ?: run {
+        return modality?.name?.toLowerCaseAsciiOnly() ?: run {
             if (this is FirCallableMemberDeclaration<*> && this.isOverride) {
                 "open?"
             } else {
@@ -343,7 +344,7 @@ class FirRenderer(builder: StringBuilder, private val mode: RenderMode = RenderM
         declaration.renderPhaseIfNeeded()
         print(
             when (declaration) {
-                is FirRegularClass -> declaration.classKind.name.toLowerCase().replace("_", " ")
+                is FirRegularClass -> declaration.classKind.name.toLowerCaseAsciiOnly().replace("_", " ")
                 is FirTypeAlias -> "typealias"
                 is FirSimpleFunction -> "fun"
                 is FirProperty -> {