Add support for expression statements in compiler passes

compiler/passes/src/code_generation/visit_expressions.rs

@@ -276,6 +276,7 @@ impl<'a> CodeGenerator<'a> {
         }
     }
 
+    // TODO: Fix to allow zero or multiple outputs.
     fn visit_call(&mut self, input: &'a CallExpression) -> (String, String) {
         let mut call_instruction = match &input.external {
             Some(external) => format!("    call {external}.aleo/{} ", input.function),

compiler/passes/src/code_generation/visit_statements.rs

@@ -18,8 +18,8 @@ use crate::CodeGenerator;
 
 use leo_ast::{
     AssignStatement, Block, ConditionalStatement, ConsoleFunction, ConsoleStatement, DecrementStatement,
-    DefinitionStatement, Expression, FinalizeStatement, IncrementStatement, IterationStatement, Mode, Output,
-    ReturnStatement, Statement,
+    DefinitionStatement, Expression, ExpressionStatement, FinalizeStatement, IncrementStatement, IterationStatement,
+    Mode, Output, ReturnStatement, Statement,
 };
 
 use itertools::Itertools;
@@ -34,6 +34,7 @@ impl<'a> CodeGenerator<'a> {
             Statement::Console(stmt) => self.visit_console(stmt),
             Statement::Decrement(stmt) => self.visit_decrement(stmt),
             Statement::Definition(stmt) => self.visit_definition(stmt),
+            Statement::Expression(stmt) => self.visit_expression_statement(stmt),
             Statement::Finalize(stmt) => self.visit_finalize(stmt),
             Statement::Increment(stmt) => self.visit_increment(stmt),
             Statement::Iteration(stmt) => self.visit_iteration(stmt),
@@ -110,6 +111,13 @@ impl<'a> CodeGenerator<'a> {
         unreachable!("DefinitionStatement's should not exist in SSA form.")
     }
 
+    fn visit_expression_statement(&mut self, input: &'a ExpressionStatement) -> String {
+        match input.expression {
+            Expression::Call(_) => self.visit_expression(&input.expression).1,
+            _ => unreachable!("ExpressionStatement's can only contain CallExpression's."),
+        }
+    }
+
     fn visit_increment(&mut self, input: &'a IncrementStatement) -> String {
         let (index, mut instructions) = self.visit_expression(&input.index);
         let (amount, amount_instructions) = self.visit_expression(&input.amount);

compiler/passes/src/static_single_assignment/rename_statement.rs

@@ -18,8 +18,8 @@ use crate::{RenameTable, StaticSingleAssigner};
 
 use leo_ast::{
     AssignStatement, Block, ConditionalStatement, ConsoleFunction, ConsoleStatement, DecrementStatement,
-    DefinitionStatement, Expression, ExpressionConsumer, FinalizeStatement, Identifier, IncrementStatement,
-    IterationStatement, ReturnStatement, Statement, StatementConsumer, TernaryExpression,
+    DefinitionStatement, Expression, ExpressionConsumer, ExpressionStatement, FinalizeStatement, Identifier,
+    IncrementStatement, IterationStatement, ReturnStatement, Statement, StatementConsumer, TernaryExpression,
 };
 use leo_span::Symbol;
 
@@ -234,6 +234,20 @@ impl StatementConsumer for StaticSingleAssigner<'_> {
         statements
     }
 
+    /// Consumes the expressions associated with `ExpressionStatement`, returning the simplified `ExpressionStatement`.
+    fn consume_expression_statement(&mut self, input: ExpressionStatement) -> Self::Output {
+        // Process the expression associated with the `ExpressionStatement`.
+        let (expression, mut statements) = self.consume_expression(input.expression);
+
+        // Add the `ExpressionStatement` to the list of produced statements.
+        statements.push(Statement::Expression(ExpressionStatement {
+            expression,
+            span: input.span,
+        }));
+
+        statements
+    }
+
     /// Consumes the expressions associated with the `FinalizeStatement`, returning the simplified `FinalizeStatement`.
     fn consume_finalize(&mut self, input: FinalizeStatement) -> Self::Output {
         let mut statements = Vec::new();

compiler/passes/src/type_checking/check_statements.rs

@@ -34,6 +34,7 @@ impl<'a> StatementVisitor<'a> for TypeChecker<'a> {
             Statement::Console(stmt) => self.visit_console(stmt),
             Statement::Decrement(stmt) => self.visit_decrement(stmt),
             Statement::Definition(stmt) => self.visit_definition(stmt),
+            Statement::Expression(stmt) => self.visit_expression_statement(stmt),
             Statement::Finalize(stmt) => self.visit_finalize(stmt),
             Statement::Increment(stmt) => self.visit_increment(stmt),
             Statement::Iteration(stmt) => self.visit_iteration(stmt),
@@ -224,6 +225,19 @@ impl<'a> StatementVisitor<'a> for TypeChecker<'a> {
         }
     }
 
+    fn visit_expression_statement(&mut self, input: &'a ExpressionStatement) {
+        // Expression statements can only be function calls.
+        if !matches!(input.expression, Expression::Call(_)) {
+            self.emit_err(TypeCheckerError::expression_statement_must_be_function_call(
+                input.span(),
+            ));
+        } else {
+            // Check the expression.
+            // TODO: Should the output type be restricted to unit types?
+            self.visit_expression(&input.expression, &None);
+        }
+    }
+
     fn visit_finalize(&mut self, input: &'a FinalizeStatement) {
         if self.is_finalize {
             self.emit_err(TypeCheckerError::finalize_in_finalize(input.span()));

errors/src/errors/type_checker/type_checker_error.rs

@@ -512,4 +512,11 @@ create_messages!(
         msg: format!("A finalize statement cannot contain tuple expressions."),
         help: None,
     }
+
+    @formatted
+    expression_statement_must_be_function_call {
+        args: (),
+        msg: format!("An expression statement must be a function call."),
+        help: None,
+    }
 );