From 0579766a366c674f52ba4ed26d1b436e78becddd Mon Sep 17 00:00:00 2001
From: Anton Trunov <anton@ton.org>
Date: Fri, 16 Aug 2024 01:05:51 +0900
Subject: [PATCH] fix: better error message if constant shadows stdlib
 identifier (#694)

---
 CHANGELOG.md                                    |  1 +
 .../scope-const-shadows-stdlib-ident.tact       |  1 +
 .../compilation-failed/scope-errors.spec.ts     | 14 ++++++++++++++
 src/test/compilation-failed/tact.config.json    |  5 +++++
 src/types/resolveStatements.ts                  | 17 +++++++++++++----
 5 files changed, 34 insertions(+), 4 deletions(-)
 create mode 100644 src/test/compilation-failed/contracts/scope-const-shadows-stdlib-ident.tact
 create mode 100644 src/test/compilation-failed/scope-errors.spec.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 636046e86..bef20a717 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Parsing of optional nested struct fields does not cause the `Not a tuple` error anymore: PR [#692](https://github.com/tact-lang/tact/pull/692)
 - Disallow shadowing of recursive function names: PR [#693](https://github.com/tact-lang/tact/pull/693)
+- Better error message for the case when a constant shadows an stdlib identifier: PR [#694](https://github.com/tact-lang/tact/pull/694)
 
 ## [1.4.2] - 2024-08-13
 
diff --git a/src/test/compilation-failed/contracts/scope-const-shadows-stdlib-ident.tact b/src/test/compilation-failed/contracts/scope-const-shadows-stdlib-ident.tact
new file mode 100644
index 000000000..2d1f11c62
--- /dev/null
+++ b/src/test/compilation-failed/contracts/scope-const-shadows-stdlib-ident.tact
@@ -0,0 +1 @@
+const b: Int = 42;
diff --git a/src/test/compilation-failed/scope-errors.spec.ts b/src/test/compilation-failed/scope-errors.spec.ts
new file mode 100644
index 000000000..2fcc16b65
--- /dev/null
+++ b/src/test/compilation-failed/scope-errors.spec.ts
@@ -0,0 +1,14 @@
+import { __DANGER_resetNodeId } from "../../grammar/ast";
+import { itShouldNotCompile } from "./util";
+
+describe("scope-errors", () => {
+    beforeEach(() => {
+        __DANGER_resetNodeId();
+    });
+
+    itShouldNotCompile({
+        testName: "scope-const-shadows-stdlib-ident",
+        errorMessage:
+            'Constant "b" is shadowing an identifier defined in the Tact standard library: pick a different constant name',
+    });
+});
diff --git a/src/test/compilation-failed/tact.config.json b/src/test/compilation-failed/tact.config.json
index a2109296f..16fab850f 100644
--- a/src/test/compilation-failed/tact.config.json
+++ b/src/test/compilation-failed/tact.config.json
@@ -136,6 +136,11 @@
       "name": "func-function-does-not-exist",
       "path": "./contracts/func-function-does-not-exist.tact",
       "output": "./contracts/output"
+    },
+    {
+      "name": "scope-const-shadows-stdlib-ident",
+      "path": "./contracts/scope-const-shadows-stdlib-ident.tact",
+      "output": "./contracts/output"
     }
   ]
 }
diff --git a/src/types/resolveStatements.ts b/src/types/resolveStatements.ts
index bb247c6bf..59b5fb9a9 100644
--- a/src/types/resolveStatements.ts
+++ b/src/types/resolveStatements.ts
@@ -20,6 +20,7 @@ import {
 import {
     getAllStaticFunctions,
     getAllTypes,
+    getStaticConstant,
     getType,
     hasStaticConstant,
     resolveTypeRef,
@@ -68,10 +69,18 @@ function checkVariableExists(
         );
     }
     if (hasStaticConstant(ctx, idText(name))) {
-        throwCompilationError(
-            `Variable ${idTextErr(name)} is trying to shadow an existing constant with the same name`,
-            name.loc,
-        );
+        if (name.loc.origin === "stdlib") {
+            const constLoc = getStaticConstant(ctx, idText(name)).loc;
+            throwCompilationError(
+                `Constant ${idTextErr(name)} is shadowing an identifier defined in the Tact standard library: pick a different constant name`,
+                constLoc,
+            );
+        } else {
+            throwCompilationError(
+                `Variable ${idTextErr(name)} is trying to shadow an existing constant with the same name`,
+                name.loc,
+            );
+        }
     }
 }