fix struct field validation. make if conditional parenthesis optional

compiler/src/constraints/expression.rs

@@ -360,6 +360,9 @@ impl<F: Field + PrimeField, CS: ConstraintSystem<F>> ConstrainedProgram<F, CS> {
                     member.expression,
                 )?;
 
+                // Check member types
+                member_value.expect_type(&field._type)?;
+
                 resolved_members.push(ConstrainedStructMember(member.variable, member_value))
             }
 

compiler/src/errors/constraints/expression.rs

@@ -1,4 +1,4 @@
-use crate::errors::{BooleanError, FieldElementError, FunctionError, IntegerError};
+use crate::errors::{BooleanError, FieldElementError, FunctionError, IntegerError, ValueError};
 
 #[derive(Debug, Error)]
 pub enum ExpressionError {
@@ -13,6 +13,9 @@ pub enum ExpressionError {
     #[error("{}", _0)]
     IncompatibleTypes(String),
 
+    #[error("{}", _0)]
+    ValueError(ValueError),
+
     #[error("{}", _0)]
     IntegerError(IntegerError),
 
@@ -81,6 +84,12 @@ impl From<std::io::Error> for ExpressionError {
     }
 }
 
+impl From<ValueError> for ExpressionError {
+    fn from(error: ValueError) -> Self {
+        ExpressionError::ValueError(error)
+    }
+}
+
 impl From<IntegerError> for ExpressionError {
     fn from(error: IntegerError) -> Self {
         ExpressionError::IntegerError(error)

compiler/src/leo.pest

@@ -174,7 +174,7 @@ statement_return = { "return" ~ expression_tuple }
 statement_definition = { "let" ~ variable ~ (":" ~ _type)? ~ "=" ~ expression }
 statement_assign = { assignee ~ operation_assign ~ expression }
 statement_multiple_assignment = { "let" ~ "(" ~ optionally_typed_variable_tuple ~ ")" ~ "=" ~  variable ~ "(" ~ expression_tuple ~ ")" }
-statement_conditional = {"if" ~ "(" ~ expression ~ ")" ~ "{" ~ NEWLINE* ~ statement+ ~ "}" ~ ("else" ~ conditional_nested_or_end)?}
+statement_conditional = {"if" ~ (expression | "(" ~ expression ~ ")") ~ "{" ~ NEWLINE* ~ statement+ ~ "}" ~ ("else" ~ conditional_nested_or_end)?}
 statement_for = { "for" ~ variable ~ "in" ~ expression ~ ".." ~ expression ~ "{" ~ NEWLINE* ~ statement+ ~ "}"}
 statement_assert = {
     assert_eq