Merge pull request #823 from Zokrates/fail-on-assertion

Detect assertion failures at compile time on constant expressions

changelogs/unreleased/823-dark64

@@ -0,0 +1 @@
+Detect assertion failures at compile time on constant expressions

zokrates_cli/examples/book/assert.zok

@@ -1,3 +1,3 @@
 def main() -> ():
-	assert(1f == 2f)
+	assert(1f + 1f == 2f)
 	return

zokrates_cli/examples/compile_errors/assertion.zok

@@ -0,0 +1,3 @@
+def main():
+    assert(1f == 2f)
+    return

zokrates_cli/examples/compile_errors/generics/assertion.zok

@@ -0,0 +1,7 @@
+def foo<N>(field[N] inputs) -> bool:
+    assert(N <= 5)
+    return true
+
+def main():
+    bool b = foo([1, 2, 3, 4, 5, 6])
+    return

zokrates_cli/examples/left_side_call.zok

@@ -2,5 +2,5 @@ def foo() -> field:
 	return 1
 
 def main():
-	assert(foo() + (1 + 44*3) == 1)
+	assert(foo() + (1 + 44*3) == 134)
 	return

zokrates_cli/examples/propagate_call.zok

@@ -1,5 +1,5 @@
 def foo(field a, field b) -> (field, field):
-	assert(a == b + 2)
+	assert(a == b)
 	return a, b
 
 def main() -> field:

zokrates_core/src/static_analysis/propagation.rs

@@ -657,6 +657,17 @@ impl<'ast, 'a, T: Field> ResultFolder<'ast, T> for Propagator<'ast, 'a, T> {
 
                 Ok(statements)
             }
+            TypedStatement::Assertion(e) => {
+                let e_str = e.to_string();
+                let expr = self.fold_boolean_expression(e)?;
+                match expr {
+                    BooleanExpression::Value(v) if !v => Err(Error::Type(format!(
+                        "Assertion failed on expression `{}`",
+                        e_str
+                    ))),
+                    _ => Ok(vec![TypedStatement::Assertion(expr)]),
+                }
+            }
             s @ TypedStatement::PushCallLog(..) => Ok(vec![s]),
             s @ TypedStatement::PopCallLog => Ok(vec![s]),
             s => fold_statement(self, s),