fix(forge lint): gas lints (#10667)

* fix: gas lints

* fix: use project paths to identify tests/scripts

Author: 0xrusowsky

crates/forge/src/cmd/lint.rs

@@ -45,6 +45,7 @@ impl LintArgs {
     pub fn run(self) -> Result<()> {
         let config = self.load_config()?;
         let project = config.project()?;
+        let path_config = config.project_paths();
 
         // Expand ignore globs and canonicalize from the get go
         let ignored = expand_globs(&config.root, config.lint.ignore.iter())?
@@ -105,7 +106,7 @@ impl LintArgs {
             return Err(eyre!("Linting not supported for this language"));
         }
 
-        let linter = SolidityLinter::new()
+        let linter = SolidityLinter::new(path_config)
             .with_json_emitter(self.json)
             .with_description(true)
             .with_lints(include)

crates/lint/src/sol/gas/keccak.rs

@@ -4,7 +4,7 @@ use crate::{
     linter::EarlyLintPass,
     sol::{Severity, SolLint},
 };
-use solar_ast::{Expr, ExprKind};
+use solar_ast::{CallArgsKind, Expr, ExprKind};
 use solar_interface::kw;
 
 declare_forge_lint!(
@@ -16,9 +16,17 @@ declare_forge_lint!(
 
 impl<'ast> EarlyLintPass<'ast> for AsmKeccak256 {
     fn check_expr(&mut self, ctx: &crate::linter::LintContext<'_>, expr: &'ast Expr<'ast>) {
-        if let ExprKind::Call(expr, _) = &expr.kind {
+        if let ExprKind::Call(expr, args) = &expr.kind {
             if let ExprKind::Ident(ident) = &expr.kind {
                 if ident.name == kw::Keccak256 {
+                    // Do not flag when hashing a single literal, as the compiler should optimize it
+                    if let CallArgsKind::Unnamed(ref exprs) = args.kind {
+                        if exprs.len() == 1 {
+                            if let ExprKind::Lit(_, _) = exprs[0].kind {
+                                return;
+                            }
+                        }
+                    }
                     ctx.emit(&ASM_KECCAK256, expr.span);
                 }
             }

crates/lint/src/sol/mod.rs

@@ -1,5 +1,5 @@
 use crate::linter::{EarlyLintPass, EarlyLintVisitor, Lint, LintContext, Linter};
-use foundry_compilers::solc::SolcLanguage;
+use foundry_compilers::{solc::SolcLanguage, ProjectPathsConfig};
 use foundry_config::lint::Severity;
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use solar_ast::{visit::Visit, Arena};
@@ -22,8 +22,9 @@ pub mod med;
 
 /// Linter implementation to analyze Solidity source code responsible for identifying
 /// vulnerabilities gas optimizations, and best practices.
-#[derive(Debug, Clone, Default)]
+#[derive(Debug, Clone)]
 pub struct SolidityLinter {
+    path_config: ProjectPathsConfig,
     severity: Option<Vec<Severity>>,
     lints_included: Option<Vec<SolLint>>,
     lints_excluded: Option<Vec<SolLint>>,
@@ -32,8 +33,9 @@ pub struct SolidityLinter {
 }
 
 impl SolidityLinter {
-    pub fn new() -> Self {
+    pub fn new(path_config: ProjectPathsConfig) -> Self {
         Self {
+            path_config,
             severity: None,
             lints_included: None,
             lints_excluded: None,
@@ -73,11 +75,15 @@ impl SolidityLinter {
         let _ = sess.enter(|| -> Result<(), diagnostics::ErrorGuaranteed> {
             // Declare all available passes and lints
             let mut passes_and_lints = Vec::new();
-            passes_and_lints.extend(gas::create_lint_passes());
             passes_and_lints.extend(high::create_lint_passes());
             passes_and_lints.extend(med::create_lint_passes());
             passes_and_lints.extend(info::create_lint_passes());
 
+            // Do not apply gas-severity rules on tests and scripts
+            if !self.path_config.is_test_or_script(file) {
+                passes_and_lints.extend(gas::create_lint_passes());
+            }
+
             // Filter based on linter config
             let mut passes: Vec<Box<dyn EarlyLintPass<'_>>> = passes_and_lints
                 .into_iter()

crates/lint/testdata/Keccak256.sol

@@ -1,13 +1,19 @@
 contract AsmKeccak256 {
+
+    // constants are optimized by the compiler
+    bytes32 constant HASH = keccak256("hello");
+    bytes32 constant OTHER_HASH = keccak256(1234);
+
     constructor(uint256 a, uint256 b) {
         keccak256(abi.encodePacked(a, b)); //~NOTE: hash using inline assembly to save gas
     }
 
-    function solidityHash(uint256 a, uint256 b) public view {
-        keccak256(abi.encodePacked(a, b)); //~NOTE: hash using inline assembly to save gas
+    function solidityHash(uint256 a, uint256 b) public view returns (bytes32) {
+        bytes32 hash = keccak256(a); //~NOTE: hash using inline assembly to save gas
+        return keccak256(abi.encodePacked(a, b)); //~NOTE: hash using inline assembly to save gas
     }
 
-    function assemblyHash(uint256 a, uint256 b) public view {
+    function assemblyHash(uint256 a, uint256 b) public view returns (bytes32){
         //optimized
         assembly {
             mstore(0x00, a)

crates/lint/testdata/Keccak256.stderr

@@ -1,16 +1,24 @@
 note[asm-keccak256]: hash using inline assembly to save gas
  --> ROOT/testdata/Keccak256.sol:LL:CC
   |
-3 |         keccak256(abi.encodePacked(a, b));
+8 |         keccak256(abi.encodePacked(a, b));
   |         ---------
   |
   = help: https://book.getfoundry.sh/reference/forge/forge-lint#asm-keccak256
 
 note[asm-keccak256]: hash using inline assembly to save gas
- --> ROOT/testdata/Keccak256.sol:LL:CC
-  |
-7 |         keccak256(abi.encodePacked(a, b));
-  |         ---------
-  |
-  = help: https://book.getfoundry.sh/reference/forge/forge-lint#asm-keccak256
+  --> ROOT/testdata/Keccak256.sol:LL:CC
+   |
+12 |         bytes32 hash = keccak256(a);
+   |                        ---------
+   |
+   = help: https://book.getfoundry.sh/reference/forge/forge-lint#asm-keccak256
+
+note[asm-keccak256]: hash using inline assembly to save gas
+  --> ROOT/testdata/Keccak256.sol:LL:CC
+   |
+13 |         return keccak256(abi.encodePacked(a, b));
+   |                ---------
+   |
+   = help: https://book.getfoundry.sh/reference/forge/forge-lint#asm-keccak256