[typespec-vscode] Meta property autocomplete (#5353)

Fix #4976

metadata will prompt after '::', i.e. 'type', 'parameters', 'returnType'

.chronus/changes/meta-property-autocomplete-2024-11-19-3-21-6.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Meta property are auto-completed, current only supported '::type', '::parameters', '::returnType'

packages/compiler/src/core/checker.ts

@@ -2928,12 +2928,30 @@ export function createChecker(program: Program, resolver: NameResolver): Checker
       }
     } else if (identifier.parent && identifier.parent.kind === SyntaxKind.MemberExpression) {
       let base = resolver.getNodeLinks(identifier.parent.base).resolvedSymbol;
+
       if (base) {
         if (base.flags & SymbolFlags.Alias) {
           base = getAliasedSymbol(base, undefined);
         }
+
         if (base) {
-          addCompletions(base.exports ?? base.members);
+          if (identifier.parent.selector === "::") {
+            if (base?.node === undefined && base?.declarations && base.declarations.length > 0) {
+              // Process meta properties separately, such as `::parameters`, `::returnType`
+              const nodeModels = base?.declarations[0];
+              if (nodeModels.kind === SyntaxKind.OperationStatement) {
+                const operation = nodeModels as OperationStatementNode;
+                addCompletion("parameters", operation.symbol);
+                addCompletion("returnType", operation.symbol);
+              }
+            } else if (base?.node?.kind === SyntaxKind.ModelProperty) {
+              // Process meta properties separately, such as `::type`
+              const metaProperty = base.node as ModelPropertyNode;
+              addCompletion("type", metaProperty.symbol);
+            }
+          } else {
+            addCompletions(base.exports ?? base.members);
+          }
         }
       }
     } else {

packages/compiler/test/server/completion.test.ts

@@ -479,6 +479,97 @@ describe("identifiers", () => {
     ]);
   });
 
+  it("completes meta property '::type' on model property", async () => {
+    const completions = await complete(
+      `
+      model A{
+        name: string;
+      }
+
+      model B{
+          a: A;
+      }
+
+      model C {
+          ...B.a::┆;
+      }
+      `,
+    );
+
+    check(completions, [
+      {
+        label: "type",
+        insertText: "type",
+        kind: CompletionItemKind.Field,
+        documentation: {
+          kind: MarkupKind.Markdown,
+          value: "(model property)\n```typespec\nB.a: A\n```",
+        },
+      },
+    ]);
+  });
+
+  it("completes meta property '::parameters' and '::returnType' on operation", async () => {
+    const completions = await complete(
+      `
+      op base(one: string): void;    
+      @@doc(base::par┆, "Override");
+      `,
+    );
+
+    check(completions, [
+      {
+        label: "parameters",
+        insertText: "parameters",
+        kind: CompletionItemKind.Method,
+        documentation: {
+          kind: MarkupKind.Markdown,
+          value: "```typespec\nop base(one: string): void\n```",
+        },
+      },
+      {
+        label: "returnType",
+        insertText: "returnType",
+        kind: CompletionItemKind.Method,
+        documentation: {
+          kind: MarkupKind.Markdown,
+          value: "```typespec\nop base(one: string): void\n```",
+        },
+      },
+    ]);
+  });
+
+  it("completes meta property '::parameters' and '::returnType' using alias on operation", async () => {
+    const completions = await complete(
+      `
+      op a(@doc("base doc") one: string): void;
+      op b is a;
+      @@doc(b::par┆, "override for b");
+      `,
+    );
+
+    check(completions, [
+      {
+        label: "parameters",
+        insertText: "parameters",
+        kind: CompletionItemKind.Method,
+        documentation: {
+          kind: MarkupKind.Markdown,
+          value: "```typespec\nop b(one: string): void\n```",
+        },
+      },
+      {
+        label: "returnType",
+        insertText: "returnType",
+        kind: CompletionItemKind.Method,
+        documentation: {
+          kind: MarkupKind.Markdown,
+          value: "```typespec\nop b(one: string): void\n```",
+        },
+      },
+    ]);
+  });
+
   it("completes partial identifiers", async () => {
     const completions = await complete(
       `