support @receiver KDoc tag; somewhat more precise tag name completion

compiler/frontend/src/org/jetbrains/kotlin/kdoc/parser/KDocKnownTag.kt

@@ -23,6 +23,7 @@ enum class KDocKnownTag private constructor(val isReferenceRequired: Boolean, va
     THROWS(true, false),
     EXCEPTION(true, false),
     PARAM(true, false),
+    RECEIVER(false, false),
     RETURN(false, false),
     SEE(true, false),
     SINCE(false, false),

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KDocCompletionContributor.kt

@@ -32,8 +32,13 @@ import org.jetbrains.kotlin.idea.util.CallType
 import org.jetbrains.kotlin.idea.util.substituteExtensionIfCallable
 import org.jetbrains.kotlin.kdoc.lexer.KDocTokens
 import org.jetbrains.kotlin.kdoc.parser.KDocKnownTag
+import org.jetbrains.kotlin.kdoc.psi.api.KDoc
 import org.jetbrains.kotlin.kdoc.psi.impl.KDocLink
 import org.jetbrains.kotlin.kdoc.psi.impl.KDocName
+import org.jetbrains.kotlin.psi.KtClassOrObject
+import org.jetbrains.kotlin.psi.KtDeclaration
+import org.jetbrains.kotlin.psi.KtNamedFunction
+import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.resolve.BindingContext
@@ -134,9 +139,19 @@ object KDocTagCompletionProvider: CompletionProvider<CompletionParameters>() {
         if (prefix.length > 0 && !prefix.startsWith('@')) {
             return
         }
+        val kdocOwner = parameters.position.getNonStrictParentOfType<KDoc>()?.getOwner()
         val resultWithPrefix = result.withPrefixMatcher(prefix)
         KDocKnownTag.values().forEach {
-            resultWithPrefix.addElement(LookupElementBuilder.create("@" + it.name.toLowerCase()))
+            if (kdocOwner == null || it.isApplicable(kdocOwner)) {
+                resultWithPrefix.addElement(LookupElementBuilder.create("@" + it.name.toLowerCase()))
+            }
         }
     }
+
+    private fun KDocKnownTag.isApplicable(declaration: KtDeclaration) = when(this) {
+        KDocKnownTag.CONSTRUCTOR, KDocKnownTag.PROPERTY -> declaration is KtClassOrObject
+        KDocKnownTag.RETURN -> declaration is KtNamedFunction
+        KDocKnownTag.RECEIVER -> declaration is KtNamedFunction && declaration.receiverTypeReference != null
+        else -> true
+    }
 }

idea/idea-completion/testData/kdoc/TagName.kt

@@ -7,3 +7,4 @@ fun f(x: Int): Int {
 // EXIST: @param
 // EXIST: @return
 // EXIST: @suppress
+// ABSENT: @receiver

idea/idea-completion/testData/kdoc/TagNameInClass.kt

@@ -0,0 +1,12 @@
+/**
+ * <caret>
+ */
+class C<T> {
+}
+
+// EXIST: @param
+// EXIST: @suppress
+// EXIST: @constructor
+// EXIST: @property
+// ABSENT: @return
+// ABSENT: @receiver

idea/idea-completion/testData/kdoc/TagNameInExtensionFunction.kt

@@ -0,0 +1,12 @@
+/**
+ * <caret>
+ */
+fun Int.f(): Int {
+}
+
+// EXIST: @param
+// EXIST: @return
+// EXIST: @suppress
+// EXIST: @receiver
+// ABSENT: @constructor
+// ABSENT: @property

idea/idea-completion/tests/org/jetbrains/kotlin/idea/completion/test/KDocCompletionTestGenerated.java

@@ -77,6 +77,18 @@ public class KDocCompletionTestGenerated extends AbstractJvmBasicCompletionTest
         doTest(fileName);
     }
 
+    @TestMetadata("TagNameInClass.kt")
+    public void testTagNameInClass() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/kdoc/TagNameInClass.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("TagNameInExtensionFunction.kt")
+    public void testTagNameInExtensionFunction() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/kdoc/TagNameInExtensionFunction.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("TagNameMiddle.kt")
     public void testTagNameMiddle() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/idea-completion/testData/kdoc/TagNameMiddle.kt");

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

@@ -33,6 +33,7 @@ object KDocRenderer {
         result.append(markdownToHtml(content, allowSingleParagraph = true))
         if (docComment is KDocSection) {
             result.append("\n")
+            renderTag(docComment.findTagByName("receiver"), "Receiver", result)
             val paramTags = docComment.findTagsByName("param").filter { it.getSubjectName() != null }
             renderTagList(paramTags, "Parameters", result)
 

idea/testData/editor/quickDoc/OnMethodUsageWithReceiver.kt

@@ -0,0 +1,19 @@
+/**
+Some documentation
+
+ * @receiver Some int
+ * @param b String
+ * @return Return [a] and nothing else
+ */
+fun Int.testMethod(b: String) {
+
+}
+
+fun test() {
+    1.<caret>testMethod("value")
+}
+
+//INFO: <b>public</b> <b>fun</b> Int.testMethod(b: String): Unit <i>defined in</i> root package<p>Some documentation</p>
+//INFO: <dl><dt><b>Receiver:</b></dt><dd>Some int</dd></dl>
+//INFO: <dl><dt><b>Parameters:</b></dt><dd><code>b</code> - String</dd></dl>
+//INFO: <dl><dt><b>Returns:</b></dt><dd>Return <a href="psi_element://a">a</a> and nothing else</dd></dl>

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

@@ -143,6 +143,12 @@ public class QuickDocProviderTestGenerated extends AbstractQuickDocProviderTest
         doTest(fileName);
     }
 
+    @TestMetadata("OnMethodUsageWithReceiver.kt")
+    public void testOnMethodUsageWithReceiver() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/editor/quickDoc/OnMethodUsageWithReceiver.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("OnMethodUsageWithReturnAndLink.kt")
     public void testOnMethodUsageWithReturnAndLink() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/editor/quickDoc/OnMethodUsageWithReturnAndLink.kt");