fix: empty cbc (#1351)

Cargo.toml

@@ -3,7 +3,7 @@ members = ["rust-tests"]
 
 [package]
 name = "rattler-build"
-version = "0.35.4"
+version = "0.35.5"
 authors = ["rattler-build contributors <[email protected]>"]
 repository = "https://github.com/prefix-dev/rattler-build"
 edition = "2021"

py-rattler-build/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "py-rattler-build"
-version = "0.35.4"
+version = "0.35.5"
 edition = "2021"
 license = "BSD-3-Clause"
 publish = false

src/conda_build_config.rs

@@ -115,10 +115,22 @@ pub fn load_conda_build_config(
         )
     })?;
 
+    if value.is_null() {
+        return Ok(VariantConfig::default());
+    }
+
     // filter all empty maps
     let value = value
         .as_mapping()
-        .unwrap()
+        .ok_or_else(|| {
+            VariantConfigError::IOError(
+                path.to_path_buf(),
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    "Expected `conda_build_config.yaml` to be a mapping",
+                ),
+            )
+        })?
         .clone()
         .into_iter()
         .filter(|(_, v)| !v.is_null())
@@ -181,6 +193,7 @@ mod tests {
 
     #[rstest]
     #[case("conda_build_config/test_1.yaml", None)]
+    #[case("conda_build_config/all_filtered.yaml", None)]
     #[case("conda_build_config/conda_forge_subset.yaml", Some(false))]
     #[case("conda_build_config/conda_forge_subset.yaml", Some(true))]
     #[case("conda_build_config/conda_forge_subset.yaml", None)]

src/snapshots/rattler_build__conda_build_config__tests__conda_build_config__all_filtered.yaml_none.snap

@@ -0,0 +1,6 @@
+---
+source: src/conda_build_config.rs
+expression: config
+---
+pin_run_as_build: ~
+zip_keys: ~

test-data/conda_build_config/all_filtered.yaml

@@ -0,0 +1,2 @@
+c_stdlib_version:   # [false]
+  - 10.15           # [false]