Unused variable detection

.gitignore

@@ -2,3 +2,4 @@
 Cargo.lock
 /target
 **/*.rs.bk
+

Cargo.toml

@@ -30,7 +30,7 @@ serde = "1.0"
 serde_derive = { version = "1.0" }
 inkwell = { version = "0.1.0-beta.2", features = ["target-webassembly", "target-bpf", "llvm11-0"] }
 blake2-rfc = "0.2.18"
-phf = { version = "0.8", features = ["macros"] }
+phf = { version = "0.9", features = ["macros"] }
 unicode-xid = "0.2.0"
 handlebars = "3.4"
 contract-metadata = "0.2.0"
@@ -54,7 +54,7 @@ ethereum-types = "0.10"
 wasmi = "0.9"
 rand = "0.8"
 sha2 = "0.9"
-solana_rbpf = "0.2"
+solana_rbpf = "^0.2.11"
 byteorder = "1.3"
 assert_cmd = "1.0"
 bincode = "1.3"

build.rs

@@ -11,7 +11,7 @@ fn main() {
     let cxxflags = Command::new("llvm-config")
         .args(&["--cxxflags"])
         .output()
-        .unwrap();
+        .expect("could not execute llvm-config");
 
     let cxxflags = String::from_utf8(cxxflags.stdout).unwrap();
 

src/codegen/cfg.rs

@@ -616,6 +616,12 @@ impl ControlFlowGraph {
                 ty.to_string(ns),
                 self.expr_to_string(contract, ns, e)
             ),
+            Expression::BytesCast(_, ty, from, e) => format!(
+                "{} from:{} ({})",
+                ty.to_string(ns),
+                from.to_string(ns),
+                self.expr_to_string(contract, ns, e)
+            ),
             Expression::Builtin(_, _, builtin, args) => format!(
                 "(builtin {:?} ({}))",
                 builtin,

src/codegen/constant_folding.rs

@@ -1062,7 +1062,7 @@ fn expression(
         | Expression::FormatString { .. }
         | Expression::InternalFunctionCfg(_) => (expr.clone(), false),
         // nothing else is permitted in cfg
-        _ => unreachable!(),
+        _ => panic!("expr should not be in cfg: {:?}", expr),
     }
 }
 

src/codegen/expression.rs

@@ -708,6 +708,12 @@ pub fn expression(
                 )
             }
         }
+        Expression::BytesCast(loc, ty, from, e) => Expression::BytesCast(
+            *loc,
+            ty.clone(),
+            from.clone(),
+            Box::new(expression(e, cfg, contract_no, ns, vartab)),
+        ),
         Expression::Load(loc, ty, e) => Expression::Load(
             *loc,
             ty.clone(),
@@ -1784,24 +1790,25 @@ fn array_subscript(
             Type::Bytes(array_length) => {
                 let res_ty = Type::Bytes(1);
                 let from_ty = Type::Bytes(*array_length);
+                let index_ty = Type::Uint(*array_length as u16 * 8);
 
                 Expression::Trunc(
                     *loc,
                     res_ty,
                     Box::new(Expression::ShiftRight(
                         *loc,
-                        from_ty.clone(),
+                        from_ty,
                         Box::new(array),
                         // shift by (array_length - 1 - index) * 8
                         Box::new(Expression::ShiftLeft(
                             *loc,
-                            from_ty.clone(),
+                            index_ty.clone(),
                             Box::new(Expression::Subtract(
                                 *loc,
-                                from_ty.clone(),
+                                index_ty.clone(),
                                 Box::new(Expression::NumberLiteral(
                                     *loc,
-                                    from_ty.clone(),
+                                    index_ty.clone(),
                                     BigInt::from_u8(array_length - 1).unwrap(),
                                 )),
                                 Box::new(cast_shift_arg(
@@ -1814,7 +1821,7 @@ fn array_subscript(
                             )),
                             Box::new(Expression::NumberLiteral(
                                 *loc,
-                                from_ty,
+                                index_ty,
                                 BigInt::from_u8(3).unwrap(),
                             )),
                         )),

src/sema/ast.rs

@@ -62,6 +62,7 @@ pub struct EventDecl {
     pub fields: Vec<Parameter>,
     pub signature: String,
     pub anonymous: bool,
+    pub used: bool,
 }
 
 impl fmt::Display for EventDecl {
@@ -284,6 +285,8 @@ pub struct Variable {
     pub visibility: pt::Visibility,
     pub constant: bool,
     pub initializer: Option<Expression>,
+    pub assigned: bool,
+    pub read: bool,
 }
 
 #[derive(Clone, PartialEq)]

src/sema/builtin.rs

@@ -467,7 +467,7 @@ pub fn resolve_call(
     args: &[pt::Expression],
     contract_no: Option<usize>,
     ns: &mut Namespace,
-    symtable: &Symtable,
+    symtable: &mut Symtable,
     is_constant: bool,
     diagnostics: &mut Vec<Diagnostic>,
 ) -> Result<Expression, ()> {
@@ -590,7 +590,7 @@ pub fn resolve_method_call(
     args: &[pt::Expression],
     contract_no: Option<usize>,
     ns: &mut Namespace,
-    symtable: &Symtable,
+    symtable: &mut Symtable,
     diagnostics: &mut Vec<Diagnostic>,
 ) -> Result<Expression, ()> {
     // The abi.* functions need special handling, others do not

src/sema/contracts.rs

@@ -13,6 +13,7 @@ use super::statements;
 use super::symtable::Symtable;
 use super::variables;
 use super::{ast, SOLANA_FIRST_OFFSET};
+use crate::sema::unused_variable::emit_warning_local_variable;
 use crate::{emit, Target};
 
 impl ast::Contract {
@@ -249,7 +250,7 @@ fn resolve_base_args(
                     .position(|e| e.contract_no == base_no)
                 {
                     if let Some(args) = &base.args {
-                        let symtable = Symtable::new();
+                        let mut symtable = Symtable::new();
 
                         // find constructor which matches this
                         if let Ok((Some(constructor_no), args)) = match_constructor_to_args(
@@ -259,7 +260,7 @@ fn resolve_base_args(
                             base_no,
                             *contract_no,
                             ns,
-                            &symtable,
+                            &mut symtable,
                             &mut diagnostics,
                         ) {
                             ns.contracts[*contract_no].bases[pos].constructor =
@@ -868,6 +869,12 @@ fn resolve_bodies(
             .is_err()
         {
             broken = true;
+        } else {
+            for variable in ns.functions[function_no].symtable.vars.values() {
+                if let Some(warning) = emit_warning_local_variable(&variable) {
+                    ns.diagnostics.push(warning);
+                }
+            }
         }
     }