Avoid computing AST for IdentifierChecker

Basically, it's unnecessary to check anything when analysing stubs,
but it's complicated now to avoid that, so we just postpone
computing AST until reporting happens

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/JvmSimpleNameBacktickChecker.kt

@@ -26,10 +26,8 @@ object JvmSimpleNameBacktickChecker : IdentifierChecker {
     // See The Java Virtual Machine Specification, section 4.7.9.1 https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.9.1
     private val CHARS = setOf('.', ';', '[', ']', '/', '<', '>', ':', '\\')
 
-    override fun checkIdentifier(identifier: PsiElement?, diagnosticHolder: DiagnosticSink) {
-        if (identifier == null) return
-
-        reportIfNeeded(identifier.text, identifier, diagnosticHolder)
+    override fun checkIdentifier(simpleNameExpression: KtSimpleNameExpression, diagnosticHolder: DiagnosticSink) {
+        reportIfNeeded(simpleNameExpression.getReferencedName(), { simpleNameExpression.getIdentifier() }, diagnosticHolder)
     }
 
     override fun checkDeclaration(declaration: KtDeclaration, diagnosticHolder: DiagnosticSink) {
@@ -50,17 +48,22 @@ object JvmSimpleNameBacktickChecker : IdentifierChecker {
     private fun checkNamed(declaration: KtNamedDeclaration, diagnosticHolder: DiagnosticSink) {
         val name = declaration.name ?: return
 
-        val element = declaration.nameIdentifier ?: declaration
-        reportIfNeeded(name, element, diagnosticHolder)
+        reportIfNeeded(name, { declaration.nameIdentifier ?: declaration }, diagnosticHolder)
     }
 
-    private fun reportIfNeeded(name: String, element: PsiElement, diagnosticHolder: DiagnosticSink) {
+    private fun reportIfNeeded(name: String, reportOn: () -> PsiElement?, diagnosticHolder: DiagnosticSink) {
         val text = KtPsiUtil.unquoteIdentifier(name)
         if (text.isEmpty()) {
-            diagnosticHolder.report(Errors.INVALID_CHARACTERS.on(element, "should not be empty"))
-        }
-        else if (text.any { it in CHARS }) {
-            diagnosticHolder.report(Errors.INVALID_CHARACTERS.on(element, "contains illegal characters: ${CHARS.intersect(text.toSet()).joinToString("")}"))
+            diagnosticHolder.report(Errors.INVALID_CHARACTERS.on(reportOn() ?: return, "should not be empty"))
+        } else if (text.any { it in CHARS }) {
+            diagnosticHolder.report(
+                Errors.INVALID_CHARACTERS.on(
+                    reportOn() ?: return,
+                    "contains illegal characters: ${CHARS.intersect(text.toSet()).joinToString(
+                        ""
+                    )}"
+                )
+            )
         }
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/IdentifierChecker.kt

@@ -16,16 +16,16 @@
 
 package org.jetbrains.kotlin.resolve
 
-import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtSimpleNameExpression
 
 interface IdentifierChecker {
-    fun checkIdentifier(identifier: PsiElement?, diagnosticHolder: DiagnosticSink)
+    fun checkIdentifier(simpleNameExpression: KtSimpleNameExpression, diagnosticHolder: DiagnosticSink)
     fun checkDeclaration(declaration: KtDeclaration, diagnosticHolder: DiagnosticSink)
 
     object Default : IdentifierChecker {
-        override fun checkIdentifier(identifier: PsiElement?, diagnosticHolder: DiagnosticSink) {}
+        override fun checkIdentifier(simpleNameExpression: KtSimpleNameExpression, diagnosticHolder: DiagnosticSink) {}
         override fun checkDeclaration(declaration: KtDeclaration, diagnosticHolder: DiagnosticSink) {}
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/LazyTopDownAnalyzer.kt

@@ -102,7 +102,7 @@ class LazyTopDownAnalyzer(
                 }
 
                 override fun visitPackageDirective(directive: KtPackageDirective) {
-                    directive.packageNames.forEach { identifierChecker.checkIdentifier(it.getIdentifier(), trace) }
+                    directive.packageNames.forEach { identifierChecker.checkIdentifier(it, trace) }
                     qualifiedExpressionResolver.resolvePackageHeader(directive, moduleDescriptor, trace)
                 }
 

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsIdentifierChecker.kt

@@ -16,19 +16,20 @@
 
 package org.jetbrains.kotlin.js.resolve.diagnostics
 
-import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.js.naming.NameSuggestion
 import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtSimpleNameExpression
 import org.jetbrains.kotlin.resolve.IdentifierChecker
 
 object JsIdentifierChecker : IdentifierChecker {
-    override fun checkIdentifier(identifier: PsiElement?, diagnosticHolder: DiagnosticSink) {
-        if (identifier == null) return
+    override fun checkIdentifier(simpleNameExpression: KtSimpleNameExpression, diagnosticHolder: DiagnosticSink) {
+        val simpleName = simpleNameExpression.getReferencedName()
 
-        val hasIllegalChars = identifier.text.split('.').any { NameSuggestion.sanitizeName(it) != it }
+        val hasIllegalChars = simpleName.split('.').any { NameSuggestion.sanitizeName(it) != it }
         if (hasIllegalChars) {
+            val identifier = simpleNameExpression.getIdentifier() ?: return
             diagnosticHolder.report(Errors.INVALID_CHARACTERS.on(identifier, "contains illegal characters"))
         }
     }