From a9b8fdcad6161417dbef278fd873d48dbbd06fe8 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Tue, 19 Oct 2021 20:35:53 -0700
Subject: [PATCH] Track duplicate record definitions

---
 schala-lang/language/src/symbol_table/mod.rs  | 46 ++++++++++---------
 schala-lang/language/src/symbol_table/test.rs | 25 ++++++++++
 2 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/schala-lang/language/src/symbol_table/mod.rs b/schala-lang/language/src/symbol_table/mod.rs
index 0310f01..e8d024f 100644
--- a/schala-lang/language/src/symbol_table/mod.rs
+++ b/schala-lang/language/src/symbol_table/mod.rs
@@ -1,5 +1,4 @@
-use std::collections::HashMap;
-use std::collections::hash_map::Entry;
+use std::collections::{HashMap, hash_map::Entry};
 use std::rc::Rc;
 use std::fmt;
 
@@ -58,6 +57,11 @@ pub enum SymbolError {
   DuplicateName {
     prev_name: FQSN,
     location: Location
+  },
+  DuplicateRecord {
+    type_name: FQSN,
+    location: Location,
+    member: String,
   }
 }
 
@@ -301,6 +305,7 @@ impl SymbolTable {
   }
 
   fn add_type_members(&mut self, type_name: &TypeSingletonName, type_body: &TypeBody, _mutable: &bool, location: Location, scope_stack: &mut Vec<Scope>) -> Vec<SymbolError> {
+    let mut member_errors = vec![];
     let mut errors = vec![];
 
     let mut register = |fqsn: FQSN, spec: SymbolSpec| {
@@ -343,6 +348,23 @@ impl SymbolTable {
         },
         Variant::Record { name, members } => {
           let fq_name = FQSN::from_scope_stack(scope_stack.as_ref(), name.clone());
+
+          let mut seen_members = HashMap::new();
+          for (member_name, _) in members.iter() {
+            match seen_members.entry(member_name.as_ref()) {
+              Entry::Occupied(o) => {
+                let location = *o.get();
+                member_errors.push(SymbolError::DuplicateRecord {
+                  type_name: fq_name.clone(),
+                  location,
+                  member: member_name.as_ref().to_string(),
+                });
+              },
+              //TODO eventually this should track meaningful locations
+              Entry::Vacant(v) => { v.insert(Location::default()); }
+            }
+          }
+
           let spec = SymbolSpec::RecordConstructor {
             index,
             type_name: name.clone(),
@@ -350,30 +372,12 @@ impl SymbolTable {
               .map(|(_, _)| (Rc::new("DUMMY_FIELD".to_string()), Rc::new("DUMMY_TYPE_ID".to_string()))).collect()
           };
           register(fq_name, spec);
-          //TODO check for duplicates among struct member definitions
-          /*
-
-          let mut duplicate_member_definitions = Vec::new();
-          for (member_name, member_type) in defined_members {
-            match members.entry(member_name.clone()) {
-              Entry::Occupied(_) => duplicate_member_definitions.push(member_name.clone()),
-              Entry::Vacant(v) => {
-                v.insert(match member_type {
-                  TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(),
-                  TypeIdentifier::Tuple(_) => unimplemented!(),
-                });
-              }
-            }
-          }
-          if duplicate_member_definitions.len() != 0 {
-            return Err(format!("Duplicate member(s) in definition of type {}: {:?}", type_name, duplicate_member_definitions));
-          }
-          */
         }
       }
     }
 
     scope_stack.pop();
+    errors.extend(member_errors.into_iter());
     errors
   }
 }
diff --git a/schala-lang/language/src/symbol_table/test.rs b/schala-lang/language/src/symbol_table/test.rs
index 28a3843..c815912 100644
--- a/schala-lang/language/src/symbol_table/test.rs
+++ b/schala-lang/language/src/symbol_table/test.rs
@@ -206,3 +206,28 @@ fn duplicate_modules() {
   );
 
 }
+
+#[test]
+fn duplicate_struct_members() {
+  //TODO this is a parser error
+  /*
+  let source = r#"
+    type Tarak = Tarak {
+      loujet: i32,
+      mets: i32,
+      mets: i32,
+    }
+  "#;
+  */
+
+  let source = r#" type Tarak = Tarak { loujet: i32, mets: i32, mets: i32 } "#;
+
+  let (_, output) = add_symbols(source);
+  let errs = output.unwrap_err();
+  assert_matches!(&errs[..], [
+    SymbolError::DuplicateRecord { 
+      type_name, member, ..},
+  ] if type_name == &FQSN::from_strs(&["Tarak", "Tarak"]) && member == "mets"
+  );
+
+}