Fix handling of underscores in Markdown links (KT-14452)

idea/src/org/jetbrains/kotlin/idea/kdoc/KDocRenderer.kt

@@ -170,8 +170,12 @@ object KDocRenderer {
                 }
                 MarkdownElementTypes.SHORT_REFERENCE_LINK,
                 MarkdownElementTypes.FULL_REFERENCE_LINK -> {
-                    val label = node.child(MarkdownElementTypes.LINK_LABEL)?.child(MarkdownTokenTypes.TEXT)?.text
-                    if (label != null) {
+                    val linkLabelNode = node.child(MarkdownElementTypes.LINK_LABEL)
+                    val linkLabelContent = linkLabelNode?.children
+                            ?.dropWhile { it.type == MarkdownTokenTypes.LBRACKET }
+                            ?.dropLastWhile { it.type == MarkdownTokenTypes.RBRACKET }
+                    if (linkLabelContent != null) {
+                        val label = linkLabelContent.joinToString(separator = "") { it.text }
                         val linkText = node.child(MarkdownElementTypes.LINK_TEXT)?.toHtml() ?: label
                         DocumentationManagerUtil.createHyperlink(sb, label, linkText, true)
                     }

idea/testData/editor/quickDoc/AtConstantWithUnderscore.kt

@@ -0,0 +1,12 @@
+class C {
+    /** Use [SOME_REFERENCED_VAL] to do something */
+    fun fo<caret>o() {
+
+    }
+
+    companion object {
+        val SOME_REFERENCED_VAL = 1
+    }
+}
+
+//INFO: <b>public</b> <b>final</b> <b>fun</b> foo(): Unit <i>defined in</i> C<p>Use <a href="psi_element://SOME_REFERENCED_VAL">SOME_REFERENCED_VAL</a> to do something</p>

idea/tests/org/jetbrains/kotlin/idea/editor/quickDoc/QuickDocProviderTestGenerated.java

@@ -35,6 +35,12 @@ public class QuickDocProviderTestGenerated extends AbstractQuickDocProviderTest
         KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/editor/quickDoc"), Pattern.compile("^([^_]+)\\.[^\\.]*$"), true);
     }
 
+    @TestMetadata("AtConstantWithUnderscore.kt")
+    public void testAtConstantWithUnderscore() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/editor/quickDoc/AtConstantWithUnderscore.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("AtFunctionParameter.kt")
     public void testAtFunctionParameter() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/editor/quickDoc/AtFunctionParameter.kt");