Fix #2533.

common/changes/@typespec/compiler/booleanTrueFix_2023-10-17-22-35.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/compiler",
+      "comment": "Fix issue where true and false were not treated as assignable to boolean.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/compiler"
+}

common/changes/@typespec/openapi3/booleanTrueFix_2023-10-17-22-35.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@typespec/openapi3",
+      "comment": "",
+      "type": "none"
+    }
+  ],
+  "packageName": "@typespec/openapi3"
+}

packages/compiler/src/core/checker.ts

@@ -5253,6 +5253,10 @@ export function createChecker(program: Program): Checker {
       return source.kind === ReflectionNameToKind[target.name];
     }
 
+    if (source.kind === "Boolean" && target.kind === "Scalar" && target.name === "boolean") {
+      return true;
+    }
+
     if (target.kind === "Scalar") {
       return isRelatedToScalar(source, target);
     }

packages/openapi3/test/overloads.test.ts

@@ -109,4 +109,19 @@ describe("openapi3: overloads", () => {
       }
     `);
   });
+
+  it("can overload a boolean property with true or false", async () => {
+    const _ = await openApiFor(`
+      @test
+      op someThing(param: boolean): string | int32;
+
+      @test
+      @overload(someThing)
+      op someStringThing(param: true): string;
+      
+      @test
+      @overload(someThing)
+      op someNumberThing(param: false): int32;
+    `);
+  });
 });