fix: check for getter method ids collisions (#875)

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Collisions in getter method ids are now handled and reported properly: PR [#875](https://github.com/tact-lang/tact/pull/875)
+
 ### Release contributors
 
 ## [1.5.2] - 2024-09-25

src/types/__snapshots__/resolveDescriptors.spec.ts.snap

@@ -328,6 +328,39 @@ Line 4, col 17:
 "
 `;
 
+exports[`resolveDescriptors should fail descriptors for getter-collision 1`] = `
+"<unknown>:8:13: Method ID collision: getter 'pko' has the same method ID 103057 as getter 'getter1'
+Pick a different getter name to avoid collisions
+Line 8, col 13:
+  7 | 
+> 8 |     get fun pko() {
+                  ^~~
+  9 |         return;
+"
+`;
+
+exports[`resolveDescriptors should fail descriptors for getter-collision-trait 1`] = `
+"<unknown>:8:13: Method ID collision: getter 'pko' has the same method ID 103057 as getter 'getter1'
+Pick a different getter name to avoid collisions
+Line 8, col 13:
+  7 | 
+> 8 |     get fun pko() {
+                  ^~~
+  9 |         return;
+"
+`;
+
+exports[`resolveDescriptors should fail descriptors for getter-collision-with-trait 1`] = `
+"<unknown>:4:13: Method ID collision: getter 'pko' has the same method ID 103057 as getter 'getter1'
+Pick a different getter name to avoid collisions
+Line 4, col 13:
+  3 | trait T {
+> 4 |     get fun pko() {
+                  ^~~
+  5 |         return;
+"
+`;
+
 exports[`resolveDescriptors should fail descriptors for getter-outside-contract 1`] = `
 "<unknown>:8:1: Getters must be defined within a contract
 Line 8, col 1:

src/types/resolveDescriptors.ts

@@ -52,6 +52,7 @@ import { ItemOrigin } from "../grammar/grammar";
 import { getExpType, resolveExpression } from "./resolveExpression";
 import { emptyContext } from "./resolveStatements";
 import { isAssignable } from "./subtyping";
+import { getMethodId } from "../utils/utils";
 
 const store = createContextStore<TypeDescription>();
 const staticFunctionsStore = createContextStore<FunctionDescription>();
@@ -1916,6 +1917,25 @@ export function resolveDescriptors(ctx: CompilerContext) {
         staticConstants.set(idText(a.name), buildConstantDescription(a));
     }
 
+    // Check for collisions in getter method IDs
+    for (const t of types.values()) {
+        const methodIds: Map<number, string> = new Map();
+        for (const f of t.functions.values()) {
+            if (f.isGetter) {
+                const methodId = getMethodId(f.name);
+                const existing = methodIds.get(methodId);
+                if (existing) {
+                    throwCompilationError(
+                        `Method ID collision: getter '${f.name}' has the same method ID ${methodId} as getter '${existing}'\nPick a different getter name to avoid collisions`,
+                        f.ast.name.loc,
+                    );
+                } else {
+                    methodIds.set(methodId, f.name);
+                }
+            }
+        }
+    }
+
     //
     // Register types and functions in context
     //

src/types/test-failed/getter-collision-trait.tact

@@ -0,0 +1,11 @@
+trait BaseTrait { }
+
+trait T {
+    get fun getter1() {
+        return;
+    }
+
+    get fun pko() {
+        return;
+    }
+}

src/types/test-failed/getter-collision-with-trait.tact

@@ -0,0 +1,13 @@
+trait BaseTrait { }
+
+trait T {
+    get fun pko() {
+        return;
+    }
+}
+
+contract TestContract with T {
+    get fun getter1() {
+        return;
+    }
+}

src/types/test-failed/getter-collision.tact

@@ -0,0 +1,11 @@
+trait BaseTrait { }
+
+contract TestContract {
+    get fun getter1() {
+        return;
+    }
+
+    get fun pko() {
+        return;
+    }
+}