fix: better error message if constant shadows stdlib identifier

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
 

src/test/compilation-failed/contracts/scope-const-shadows-stdlib-ident.tact

@@ -0,0 +1 @@
+const b: Int = 42;

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',
+    });
+});

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"
     }
   ]
 }

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,
+            );
+        }
     }
 }