🐞️ Functions: Return position enforcement (#6)

* Parser

- Added a TODO in `wantsBody == true` case in `parseFuncDef()` to check for the return keyword's position

* Parser

- Added a check in `parseFuncDef()` which, is a `ReturnStmt` is found, then crash the parser if it is found anywhere besides the last statement

* Test cases

- Added test cases to test the `return` statement position enforcement

.github/workflows/d.yml

@@ -100,6 +100,20 @@ jobs:
           fi
       - name: Simple string
         run: ./tlang syntaxcheck source/tlang/testing/typecheck/simple_string.t
+      
+      - name: Simple return (good)
+        run: |
+          ./tlang syntaxcheck source/tlang/testing/return/simple_return_good.t
+      - name: Simple return (bad return position)
+        run: |
+          set +e
+          ./tlang syntaxcheck source/tlang/testing/return/simple_return_bad.t
+          if [ $? = 255 ]
+          then
+              exit 0
+          else
+              exit 1
+          fi
 
   typecheck:
     needs: [build, unittests]

source/tlang/compiler/parsing/core.d

@@ -974,6 +974,22 @@ public final class Parser
             /* Parse the body (and it leaves ONLY when it gets the correct symbol, no expect needed) */
             statements = parseBody();
 
+            /* TODO: We should now run through the statements in the body and check for return */
+            for(ulong i = 0; i < statements.length; i++)
+            {
+                Statement curStatement = statements[i];
+
+                /* If we find a return statement */
+                if(cast(ReturnStmt)curStatement)
+                {
+                    /* If it is not the last statement, throw an error */
+                    if(i != statements.length-1)
+                    {
+                        expect("A return statement must be the last statement of a function's body");
+                    }
+                }
+            }
+
             nextToken();
         }
         /* If no body is requested */

source/tlang/testing/return/simple_return_bad.t

@@ -0,0 +1,12 @@
+module simple_return_bad;
+
+int myFunction()
+{
+    return 1;
+}
+
+int myFunction2()
+{
+    return 2;
+    int j = 1;
+}

source/tlang/testing/return/simple_return_good.t

@@ -0,0 +1,12 @@
+module simple_return_good;
+
+int myFunction()
+{
+    return 1;
+}
+
+int myFunction2()
+{
+    int j = 1;
+    return 2;
+}