From e7a8582a965b656400cda440205385648cbd0419 Mon Sep 17 00:00:00 2001
From: Mike Lowis <mike.lowis@gentex.com>
Date: Thu, 24 Oct 2024 16:53:22 -0400
Subject: [PATCH] added checks to make sure we don't assign to string indexes

---
 cerise-c.m          | 2 --
 lib/codegen.rb      | 2 +-
 lib/lexer.rb        | 4 ++--
 lib/type_checker.rb | 5 +++++
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/cerise-c.m b/cerise-c.m
index d96fb65..1c1afd4 100644
--- a/cerise-c.m
+++ b/cerise-c.m
@@ -79,8 +79,6 @@ TestStringOps()
     assert ("foo" + "bar") == "foobar"
     assert("foo"[0] == 'f')
 
-
-
 #    assert ("foo" + 123) == "foo123"
 #    assert ("foo" + 123.0) == "foo123.000000"
 #    assert ("foo" + true) == "footrue"
diff --git a/lib/codegen.rb b/lib/codegen.rb
index ebf9be5..c5e67ee 100644
--- a/lib/codegen.rb
+++ b/lib/codegen.rb
@@ -245,7 +245,7 @@ class Codegen
       object = emit(v.name.left)
       key = emit(v.name.right)
       value = emit(v.value)
-      putln "Object_Set(#{object}, #{key}, #{value});"
+      putln "Array_Set(#{object}, #{key}, #{value});"
     else
       temp = emit(v.value)
       error v,  "invalid local definition: #{v.name.name}" if not @locals.index(v.name.name)
diff --git a/lib/lexer.rb b/lib/lexer.rb
index 98c76a3..5505280 100644
--- a/lib/lexer.rb
+++ b/lib/lexer.rb
@@ -21,7 +21,7 @@ class Lexer
 
   def linenum(pos = nil)
     pos = [pos || @data.pos].flatten.last
-    @text[0..pos].count("\n") + 1
+    (@text[0..pos].count("\n") + 1)
   end
 
   SPACE = /([ \t\v\n\r]+|#.*\n)/
@@ -71,7 +71,7 @@ class Lexer
     else
       tok = Tok.new("EOF", @file, pos, :eof)
     end
-#    pp tok
+#    pp "#{@file}:#{linenum(pos)}: #{tok.type} - #{tok.text}"
     tok
   end
 end
diff --git a/lib/type_checker.rb b/lib/type_checker.rb
index 9dcd64b..6a55031 100644
--- a/lib/type_checker.rb
+++ b/lib/type_checker.rb
@@ -252,6 +252,11 @@ class TypeChecker
 
   def infer_set(env, expr)
     type = infer(env, expr.name)
+    # TODO: check that LHS is not a string access
+    dest = expr.name
+    if (dest.is_a? IR::Op and dest.op == "[") and dest.left.type == :string
+      error(expr.loc, "cannot assign to immutable value")
+    end
     check(env, expr.value, type)
     expr.type = :void
   end
-- 
2.54.0