implement for let-statements

src/generator/writers/writeFunction.ts

@@ -90,6 +90,12 @@ export function writeStatement(
         }
         return;
     } else if (f.kind === "statement_let") {
+        // Underscore name case
+        if (f.name === "_") {
+            ctx.append(`${writeExpression(f.expression, ctx)};`);
+            return;
+        }
+
         // Contract/struct case
         const t = resolveTypeRef(ctx.ctx, f.type);
         if (t.kind === "ref") {

src/test/feature-underscore-variable.spec.ts

@@ -21,5 +21,6 @@ describe("feature-underscore-variable", () => {
         expect(await contract.getTest1()).toEqual(0n);
         expect(await contract.getTest2()).toEqual(12n);
         expect(await contract.getTest3()).toEqual(6n);
+        expect(await contract.getTest4()).toEqual(2n);
     });
 });

src/test/features/underscore-variable.tact

@@ -1,12 +1,19 @@
 contract UnderscoreVariableTestContract {
+    something: Int;
+
     init() {
-        // Nothing to do
+        self.something = 0;
     }
 
     receive() {
         // Nothing to do
     }
 
+    fun increaseSomething(): Int {
+        self.something += 1;
+        return 123;
+    }
+
     get fun test1(): Int {
         try {
             nativeThrow(1);
@@ -39,4 +46,10 @@ contract UnderscoreVariableTestContract {
         }
         return x;
     }
+
+    get fun test4(): Int {
+        let _: Int = self.increaseSomething();
+        let _: Int = self.increaseSomething();
+        return self.something;
+    }
 }

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

@@ -570,6 +570,16 @@ Line 7, col 14:
 "
 `;
 
+exports[`resolveStatements should fail statements for case-57 1`] = `
+"<unknown>:9:12: Unable to resolve id _
+Line 9, col 12:
+   8 |     let _: Int = someImpureFunction();
+>  9 |     return _;
+                  ^
+  10 | }
+"
+`;
+
 exports[`resolveStatements should resolve statements for case-0 1`] = `
 [
   [
@@ -1581,6 +1591,23 @@ exports[`resolveStatements should resolve statements for case-23 1`] = `
 `;
 
 exports[`resolveStatements should resolve statements for case-24 1`] = `
+[
+  [
+    "123",
+    "Int",
+  ],
+  [
+    "someImpureFunction()",
+    "Int",
+  ],
+  [
+    "123",
+    "Int",
+  ],
+]
+`;
+
+exports[`resolveStatements should resolve statements for case-25 1`] = `
 [
   [
     "emptyMap()",

src/types/resolveStatements.ts

@@ -187,7 +187,9 @@ function processStatements(
             if (sctx.vars.has(s.name)) {
                 throwError(`Variable "${s.name}" already exists`, s.ref);
             }
-            sctx = addVariable(s.name, variableType, sctx);
+            if (s.name !== "_") {
+                sctx = addVariable(s.name, variableType, sctx);
+            }
         } else if (s.kind === "statement_assign") {
             // Process lvalue
             ctx = resolveLValueRef(s.path, sctx, ctx);

src/types/stmts-failed/case-57.tact

@@ -0,0 +1,10 @@
+primitive Int;
+
+fun someImpureFunction(): Int {
+    return 123;
+}
+
+fun test(): Int {
+    let _: Int = someImpureFunction();
+    return _;
+}

src/types/stmts/case-24.tact

@@ -1,10 +1,10 @@
 primitive Int;
 
+fun someImpureFunction(): Int {
+    return 123;
+}
+
 fun test(): Int {
-    let m: map<Int, Int> = emptyMap();
-    let x: Int = 0;
-    foreach (_, v in m) {
-        x += v;
-    }
-    return x;
+    let _: Int = someImpureFunction();
+    return 123;
 }

src/types/stmts/case-25.tact

@@ -0,0 +1,10 @@
+primitive Int;
+
+fun test(): Int {
+    let m: map<Int, Int> = emptyMap();
+    let x: Int = 0;
+    foreach (_, v in m) {
+        x += v;
+    }
+    return x;
+}