Disable gas cfg when enable-gas=false (#1904)

Closes #1901

Author: DelevoXDG

scarb/src/ops/resolve.rs

@@ -15,8 +15,8 @@ use crate::core::registry::Registry;
 use crate::core::resolver::Resolve;
 use crate::core::workspace::Workspace;
 use crate::core::{
-    DepKind, DependencyVersionReq, FeatureName, ManifestDependency, PackageName, SourceId, Target,
-    TargetKind, TestTargetProps, TestTargetType,
+    DepKind, DependencyVersionReq, FeatureName, ManifestCompilerConfig, ManifestDependency,
+    PackageName, SourceId, Target, TargetKind, TestTargetProps, TestTargetType,
 };
 use crate::internal::to_version::ToVersion;
 use crate::ops::lockfile::{read_lockfile, write_lockfile};
@@ -414,7 +414,7 @@ fn cairo_compilation_unit_for_target(
     let packages = solution.packages.as_ref().unwrap();
     let cairo_plugins = solution.cairo_plugins.as_ref().unwrap();
 
-    let cfg_set = build_cfg_set(&member_target);
+    let cfg_set = build_cfg_set(&member_target, &member.manifest.compiler_config);
     let no_test_cfg_set = cfg_set
         .iter()
         .filter(|cfg| **cfg != Cfg::name("test"))
@@ -764,11 +764,14 @@ impl<'a> PackageSolutionCollector<'a> {
 }
 
 /// Build a set of `cfg` items to enable while building the compilation unit.
-fn build_cfg_set(target: &Target) -> CfgSet {
+fn build_cfg_set(target: &Target, compiler_config: &ManifestCompilerConfig) -> CfgSet {
     let mut cfg = CfgSet::from_iter([Cfg::kv("target", target.kind.clone())]);
     if target.is_test() {
         cfg.insert(Cfg::name("test"));
     }
+    if !compiler_config.enable_gas {
+        cfg.insert(Cfg::kv("gas", "disabled"));
+    }
     cfg
 }
 

scarb/tests/gas_cfg.rs

@@ -0,0 +1,94 @@
+use assert_fs::prelude::*;
+use assert_fs::TempDir;
+use indoc::indoc;
+use scarb_test_support::command::{CommandExt, Scarb};
+use scarb_test_support::project_builder::ProjectBuilder;
+
+#[test]
+fn gas_enabled_by_default() {
+    let t = TempDir::new().unwrap();
+    ProjectBuilder::start()
+        .name("hello")
+        .lib_cairo(indoc! {r#"
+            #[cfg(not(gas: "disabled"))]
+            fn f() -> felt252 { 42 }
+
+            #[cfg(gas: "disabled")]
+            fn f() -> felt252 { 21 }
+
+            fn main() -> felt252 {
+                f()
+            }
+        "#})
+        .build(&t);
+
+    Scarb::quick_snapbox()
+        .arg("build")
+        .current_dir(&t)
+        .assert()
+        .success();
+
+    t.child("target/dev/hello.sierra.json")
+        .assert(predicates::str::contains(
+            r#""debug_name":"Const<felt252, 42>""#,
+        ));
+}
+
+#[test]
+fn gas_disabled_with_config() {
+    let t = TempDir::new().unwrap();
+    ProjectBuilder::start()
+        .name("hello")
+        .manifest_extra(indoc! {r#"
+            [cairo]
+            enable-gas = false
+        "#})
+        .lib_cairo(indoc! {r#"
+            #[cfg(not(gas: "disabled"))]
+            fn f() -> felt252 { 42 }
+
+            #[cfg(gas: "disabled")]
+            fn f() -> felt252 { 21 }
+
+            fn main() -> felt252 {
+                f()
+            }
+        "#})
+        .build(&t);
+
+    Scarb::quick_snapbox()
+        .arg("build")
+        .current_dir(&t)
+        .assert()
+        .success();
+
+    t.child("target/dev/hello.sierra.json")
+        .assert(predicates::str::contains(
+            r#""debug_name":"Const<felt252, 21>""#,
+        ));
+}
+
+#[test]
+fn gas_disabled_in_metadata() {
+    let t = TempDir::new().unwrap();
+    ProjectBuilder::start()
+        .name("hello")
+        .manifest_extra(indoc! {r#"
+            [cairo]
+            enable-gas = false
+        "#})
+        .build(&t);
+
+    let metadata = Scarb::quick_snapbox()
+        .arg("--json")
+        .arg("metadata")
+        .arg("--format-version")
+        .arg("1")
+        .current_dir(&t)
+        .stdout_json::<scarb_metadata::Metadata>();
+
+    let unit = &metadata.compilation_units[0];
+    assert!(unit
+        .cfg
+        .contains(&scarb_metadata::Cfg::KV("gas".into(), "disabled".into())));
+}