Fix don't emit shared route error when verb don't match (#2948)

fix [#2925](https://github.com/microsoft/typespec/issues/2925)

Stop emitting the error if there is a shared route and a non shared
route on a different verb.

Also improve the error: 
- change message to be a little more clear
- emit the error on every offending operation not just the first one we
find an duplicate

---------

Co-authored-by: Brian Terlson <brian.terlson@microsoft.com>

.chronus/changes/fix-shared-route-verb-2024-1-23-18-18-26.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/http"
+---
+
+Fix don't emit shared route error when verb don't match

packages/http/src/lib.ts

@@ -102,7 +102,7 @@ export const $lib = createTypeSpecLibrary({
     "shared-inconsistency": {
       severity: "error",
       messages: {
-        default: "All shared routes must agree on the value of the shared parameter.",
+        default: paramMessage`Each operation routed at "${"verb"} ${"path"}" needs to have the @sharedRoute decorator.`,
       },
     },
     "write-visibility-not-supported": {

packages/http/src/validate.ts

@@ -2,6 +2,7 @@ import { Program } from "@typespec/compiler";
 import { reportDiagnostic } from "./lib.js";
 import { getAllHttpServices } from "./operations.js";
 import { isSharedRoute } from "./route.js";
+import { HttpOperation, HttpService } from "./types.js";
 
 export function $onValidate(program: Program) {
   // Pass along any diagnostics that might be returned from the HTTP library
@@ -9,19 +10,53 @@ export function $onValidate(program: Program) {
   if (diagnostics.length > 0) {
     program.reportDiagnostics(diagnostics);
   }
+  validateSharedRouteConsistency(program, services);
+}
+
+function groupHttpOperations(
+  operations: HttpOperation[]
+): Map<string, Map<string, HttpOperation[]>> {
+  const paths = new Map<string, Map<string, HttpOperation[]>>();
+
+  for (const operation of operations) {
+    const { verb, path } = operation;
+    let pathOps = paths.get(path);
+    if (pathOps === undefined) {
+      pathOps = new Map<string, HttpOperation[]>();
+      paths.set(path, pathOps);
+    }
+    const ops = pathOps.get(verb);
+    if (ops === undefined) {
+      pathOps.set(verb, [operation]);
+    } else {
+      ops.push(operation);
+    }
+  }
+  return paths;
+}
+function validateSharedRouteConsistency(program: Program, services: HttpService[]) {
   for (const service of services) {
-    const paths = new Map<string, boolean>();
-    for (const operation of service.operations) {
-      const path = operation.path;
-      const shared = isSharedRoute(program, operation.operation);
-      const val = paths.get(path);
-      if (shared && val === undefined) {
-        paths.set(path, shared);
-      } else if (val && val !== shared) {
-        reportDiagnostic(program, {
-          code: "shared-inconsistency",
-          target: operation.operation,
-        });
+    const paths = groupHttpOperations(service.operations);
+    for (const pathOps of paths.values()) {
+      for (const ops of pathOps.values()) {
+        let hasShared = false;
+        let hasNonShared = false;
+        for (const op of ops) {
+          if (isSharedRoute(program, op.operation)) {
+            hasShared = true;
+          } else {
+            hasNonShared = true;
+          }
+        }
+        if (hasShared && hasNonShared) {
+          for (const op of ops) {
+            reportDiagnostic(program, {
+              code: "shared-inconsistency",
+              target: op.operation,
+              format: { verb: op.verb, path: op.path },
+            });
+          }
+        }
       }
     }
   }

packages/http/test/http-decorators.test.ts

@@ -260,7 +260,7 @@ describe("http: decorators", () => {
       ]);
     });
 
-    it("emit diagnostics when not all duplicated routes are declared shared", async () => {
+    it("emit diagnostics when not all duplicated routes are declared shared on each op conflicting", async () => {
       const diagnostics = await runner.diagnose(`
         @route("/test") @sharedRoute op test(): string;
         @route("/test") @sharedRoute op test2(): string;
@@ -269,7 +269,15 @@ describe("http: decorators", () => {
       expectDiagnostics(diagnostics, [
         {
           code: "@typespec/http/shared-inconsistency",
-          message: `All shared routes must agree on the value of the shared parameter.`,
+          message: `Each operation routed at "get /test" needs to have the @sharedRoute decorator.`,
+        },
+        {
+          code: "@typespec/http/shared-inconsistency",
+          message: `Each operation routed at "get /test" needs to have the @sharedRoute decorator.`,
+        },
+        {
+          code: "@typespec/http/shared-inconsistency",
+          message: `Each operation routed at "get /test" needs to have the @sharedRoute decorator.`,
         },
       ]);
     });
@@ -283,6 +291,15 @@ describe("http: decorators", () => {
       expectDiagnosticEmpty(diagnostics);
     });
 
+    it("do not emit diagnostics routes sharing path but not same verb", async () => {
+      const diagnostics = await runner.diagnose(`
+        @route("/test") @sharedRoute op test(): string;
+        @route("/test") @sharedRoute op test2(): string;
+        @route("/test") @post op test3(): string;
+      `);
+      expectDiagnosticEmpty(diagnostics);
+    });
+
     it("emit diagnostic when wrong type for shared is provided", async () => {
       const diagnostics = await runner.diagnose(`
         @route("/test", {shared: "yes"}) op test(): string;