Error out of Api merging if there are mismatching type definitions

src/api/mod.rs

@@ -5,6 +5,7 @@ pub(crate) mod struct_enum;
 pub(crate) mod types;
 
 use aide::openapi;
+use anyhow::bail;
 use serde::{Deserialize, Serialize};
 
 use crate::cli_v1::IncludeMode;
@@ -46,18 +47,11 @@ impl Api {
 
         Ok(Self { resources, types })
     }
-}
-
-impl FromIterator<Api> for Api {
-    fn from_iter<T: IntoIterator<Item = Api>>(into_iter: T) -> Self {
-        let mut iter = into_iter.into_iter();
 
-        let mut api = iter.next().unwrap_or_default();
-        for item in iter {
-            merge_resources(&mut api.resources, item.resources);
-            api.types.extend(item.types);
-        }
-        api
+    pub(crate) fn merge(mut self, other: Self) -> anyhow::Result<Self> {
+        merge_resources(&mut self.resources, other.resources);
+        merge_types(&mut self.types, other.types)?;
+        Ok(self)
     }
 }
 
@@ -87,6 +81,23 @@ fn merge_resources(dst: &mut Resources, src: Resources) {
     }
 }
 
+fn merge_types(dst: &mut Types, src: Types) -> anyhow::Result<()> {
+    for (name, ty) in src {
+        match dst.entry(name) {
+            btree_map::Entry::Vacant(entry) => {
+                entry.insert(ty);
+            }
+            btree_map::Entry::Occupied(entry) => {
+                if *entry.get() != ty {
+                    bail!("mismatching definitions for {}", entry.key());
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
 pub(crate) fn get_schema_name(maybe_ref: Option<&str>) -> Option<String> {
     let r = maybe_ref?;
     let schema_name = r.strip_prefix("#/components/schemas/");

src/api/types.rs

@@ -80,7 +80,7 @@ pub(crate) fn from_referenced_components(
     types
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 pub(crate) struct Type {
     name: String,
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -160,7 +160,7 @@ fn fields_referenced_schemas(fields: &[Field]) -> BTreeSet<&str> {
         .collect()
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 #[serde(tag = "kind", rename_all = "snake_case")]
 pub(crate) enum TypeData {
     Struct {
@@ -271,7 +271,7 @@ impl TypeData {
     }
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 #[serde(tag = "repr", rename_all = "snake_case")]
 pub(crate) enum StructEnumRepr {
     // add more variants here to support other enum representations
@@ -303,7 +303,7 @@ impl StructEnumRepr {
     }
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 pub(crate) struct Field {
     name: String,
     #[serde(serialize_with = "serialize_field_type")]
@@ -346,7 +346,7 @@ impl Field {
     }
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 #[serde(tag = "type", rename_all = "camelCase")]
 pub(crate) enum EnumVariantType {
     Struct {
@@ -360,7 +360,7 @@ pub(crate) enum EnumVariantType {
     },
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, PartialEq)]
 pub(crate) struct SimpleVariant {
     /// Discriminator value that identifies this variant.
     pub name: String,
@@ -371,7 +371,7 @@ pub(crate) struct SimpleVariant {
 /// Supported field type.
 ///
 /// Equivalent to openapi's `type` + `format` + `$ref`.
-#[derive(Clone, Debug, Deserialize, Serialize)]
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
 #[serde(tag = "id")]
 pub(crate) enum FieldType {
     Bool,

src/cli_v1.rs

@@ -93,14 +93,14 @@ pub fn run_cli_v1_main() -> anyhow::Result<()> {
 
     let api = input_files
         .iter()
-        .map(|input_file| {
+        .try_fold(Api::default(), |result, input_file| {
             let input_file = Path::new(input_file);
             let input_file_ext = input_file
                 .extension()
                 .context("input file must have a file extension")?;
             let input_file_contents = fs::read_to_string(input_file)?;
 
-            if input_file_ext == "json" {
+            let api = if input_file_ext == "json" {
                 let spec: OpenApi = serde_json::from_str(&input_file_contents)
                     .context("failed to parse OpenAPI spec")?;
 
@@ -113,14 +113,15 @@ pub fn run_cli_v1_main() -> anyhow::Result<()> {
                     &excluded_operations,
                     &specified_operations,
                 )
-                .context("converting OpenAPI spec to our own representation")
+                .context("converting OpenAPI spec to our own representation")?
             } else if input_file_ext == "ron" {
-                ron::from_str(&input_file_contents).context("parsing ron file")
+                ron::from_str(&input_file_contents).context("parsing ron file")?
             } else {
                 bail!("input file extension must be .json or .ron");
-            }
-        })
-        .collect::<anyhow::Result<Api>>()?;
+            };
+
+            result.merge(api)
+        })?;
 
     match args.command {
         Command::Generate {