From 0955f19a816f134bcac188ec36f690e3367f30b6 Mon Sep 17 00:00:00 2001
From: Gleb Koval <gleb@koval.net>
Date: Fri, 7 Feb 2025 15:39:04 +0000
Subject: [PATCH] feat: detect function declarations mid-body

---
 src/main/wacc/parser.scala | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/main/wacc/parser.scala b/src/main/wacc/parser.scala
index dac9fcd..8098e84 100644
--- a/src/main/wacc/parser.scala
+++ b/src/main/wacc/parser.scala
@@ -6,6 +6,7 @@ import parsley.Parsley.{atomic, many, notFollowedBy, pure}
 import parsley.combinator.{countSome, sepBy}
 import parsley.expr.{precedence, SOps, InfixL, InfixN, InfixR, Prefix, Atoms}
 import parsley.errors.combinator._
+import parsley.errors.patterns.VerifiedErrors
 import parsley.syntax.zipped._
 import parsley.cats.combinator.{some}
 import cats.data.NonEmptyList
@@ -126,7 +127,7 @@ object parser {
     FuncDecl(
       sepBy(`<param>`, ",") <~ ")" <~ "is",
       `<stmt>`.guardAgainst {
-        case stmts if !stmts.isReturning => Seq("All functions must end in a returning statement")
+        case stmts if !stmts.isReturning => Seq("all functions must end in a returning statement")
       } <~ "end"
     )
   private lazy val `<param>` = Param(`<type>`, `<ident>`)
@@ -151,7 +152,13 @@ object parser {
       )
       | While("while" ~> `<expr>`.labelWithType(LabelType.Expr) <~ "do", `<stmt>` <~ "done")
       | Block("begin" ~> `<stmt>` <~ "end")
-      | VarDecl(`<type>`, `<ident>` <~ "=", `<rvalue>`.label("valid initial value for variable"))
+      | VarDecl(
+        `<type>`,
+        `<ident>` <~ ("=" | "(".verifiedExplain(
+          "all function declarations must be above the main program body"
+        )),
+        `<rvalue>`.label("valid initial value for variable")
+      )
       // TODO: Can we inline the name of the variable in the message
       | Assign(`<lvalue>` <~ "=", `<rvalue>`)
   private lazy val `<lvalue>`: Parsley[LValue] =