Get stubbed expressions in value arguments (KT-23738)

compiler/psi/src/org/jetbrains/kotlin/psi/KtLiteralStringTemplateEntry.java

@@ -34,4 +34,14 @@ public class KtLiteralStringTemplateEntry extends KtStringTemplateEntry {
     public <R, D> R accept(@NotNull KtVisitor<R, D> visitor, D data) {
         return visitor.visitLiteralStringTemplateEntry(this, data);
     }
+
+    @Override
+    public String getText() {
+        KotlinPlaceHolderWithTextStub<? extends KtStringTemplateEntry> stub = getStub();
+        if (stub != null) {
+            return stub.text();
+        }
+
+        return super.getText();
+    }
 }

compiler/psi/src/org/jetbrains/kotlin/psi/KtValueArgument.java

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.psi;
 import com.intellij.lang.ASTNode;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.impl.source.tree.LeafPsiElement;
+import com.intellij.psi.tree.TokenSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.KtNodeTypes;
@@ -45,9 +46,29 @@ public class KtValueArgument extends KtElementImplStub<KotlinPlaceHolderStub<? e
         return visitor.visitArgument(this, data);
     }
 
+    private static final TokenSet CONSTANT_EXPRESSIONS_TYPES = TokenSet.create(
+            KtStubElementTypes.NULL,
+            KtStubElementTypes.BOOLEAN_CONSTANT,
+            KtStubElementTypes.FLOAT_CONSTANT,
+            KtStubElementTypes.CHARACTER_CONSTANT,
+            KtStubElementTypes.INTEGER_CONSTANT,
+
+            KtStubElementTypes.REFERENCE_EXPRESSION,
+
+            KtStubElementTypes.STRING_TEMPLATE
+    );
+
     @Override
     @Nullable @IfNotParsed
     public KtExpression getArgumentExpression() {
+        KotlinPlaceHolderStub<? extends KtValueArgument> stub = getStub();
+        if (stub != null) {
+            KtExpression[] constantExpressions = stub.getChildrenByType(CONSTANT_EXPRESSIONS_TYPES, KtExpression.EMPTY_ARRAY);
+            if (constantExpressions.length != 0) {
+                return constantExpressions[0];
+            }
+        }
+
         return findChildByClass(KtExpression.class);
     }