From 4ad83f8abf0cc0050f53f70ff23c6c7cf17c1714 Mon Sep 17 00:00:00 2001
From: Dibyendu Majumdar <mobile@majumdar.org.uk>
Date: Sun, 25 Aug 2019 01:03:11 +0100
Subject: [PATCH] issue #98 typecheck expression statements

---
 include/ravi_ast.h                 |  5 ++-
 ravi-tests/ravi_test_ast2.expected |  2 +-
 src/ravi_ast_typecheck.c           | 61 ++++++++++++++++++++++++++++--
 3 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/include/ravi_ast.h b/include/ravi_ast.h
index 063261c..0d8ea49 100644
--- a/include/ravi_ast.h
+++ b/include/ravi_ast.h
@@ -155,11 +155,11 @@ struct ast_node {
     struct {
       struct lua_symbol_list *var_list;
       struct ast_node_list *expr_list;
-    } local_stmt;
+    } local_stmt; /* local declarations */
     struct {
       struct ast_node_list *var_expr_list; /* Optional var expressions, comma separated */
       struct ast_node_list *expr_list;      /* Comma separated expressions */
-    } expression_stmt;                     /* Also covers assignments*/
+    } expression_stmt;                     /* Also covers assignments */
     struct {
       struct ast_node *name;           /* base symbol to be looked up */
       struct ast_node_list *selectors; /* Optional */
@@ -194,6 +194,7 @@ struct ast_node {
     struct {
       struct var_type type;
     } common_expr; /* To access the type field common to all expr objects */
+    /* all expr types must be compatible with common_expr */
     struct {
       struct var_type type;
       union {
diff --git a/ravi-tests/ravi_test_ast2.expected b/ravi-tests/ravi_test_ast2.expected
index 6b8a338..935c1dd 100644
--- a/ravi-tests/ravi_test_ast2.expected
+++ b/ravi-tests/ravi_test_ast2.expected
@@ -249,7 +249,7 @@ function()
     function()
       --[expression statement start]
        --[expression list start]
-         --[suffixed expr start] closure
+         --[suffixed expr start] any
           --[primary start]
            function()
            end
diff --git a/src/ravi_ast_typecheck.c b/src/ravi_ast_typecheck.c
index 147e93a..354cbe2 100644
--- a/src/ravi_ast_typecheck.c
+++ b/src/ravi_ast_typecheck.c
@@ -190,6 +190,28 @@ static void typecheck_suffixedexpr(struct ast_node *function, struct ast_node *n
   copy_type(node->suffixed_expr.type, prev_node->common_expr.type);
 }
 
+static void typecheck_var_assignment(struct var_type *var_type, struct var_type *expr_type, const char *var_name) {
+  if (var_type->type_code == RAVI_TANY)
+    // Any value can be assigned to type ANY
+    return;
+
+  if (var_type->type_code == RAVI_TNUMINT || var_type->type_code == RAVI_TNUMFLT) {
+    if (expr_type->type_code == RAVI_TNUMINT || expr_type->type_code == RAVI_TNUMFLT) {
+      // Okay
+      // TODO insert a typecast?
+    }
+    else {
+      fprintf(stderr, "Assignment to local symbol %s is not type compatible\n", var_name);
+    }
+    return;
+  }
+
+  // all other types must strictly match
+  if (!is_type_same(*var_type, *expr_type)) { // We should probably check type convertability here
+    fprintf(stderr, "Assignment to local symbol %s is not type compatible\n", var_name);
+  }
+}
+
 static void typecheck_local_statement(struct ast_node *function, struct ast_node *node) {
   // The local vars should already be annotated
   // We need to typecheck the expressions to the right of =
@@ -207,15 +229,47 @@ static void typecheck_local_statement(struct ast_node *function, struct ast_node
     if (!var || !expr)
       break;
 
-    if (var->value_type.type_code != RAVI_TANY && !is_type_same(var->value_type, expr->common_expr.type)) { // We should probably check type convertability here
-      fprintf(stderr, "Assignment to local symbol %s is not type compatible\n", getstr(var->var.var_name));
-    }
+    struct var_type *var_type = &var->value_type;
+    struct var_type *expr_type = &expr->common_expr.type;
+    const char *var_name = getstr(var->var.var_name);
+
+    typecheck_var_assignment(var_type, expr_type, var_name);
+
+    NEXT_PTR_LIST(var);
+    NEXT_PTR_LIST(expr);
+  }
+}
+
+static void typecheck_expr_statement(struct ast_node *function, struct ast_node *node) {
+
+  if (node->expression_stmt.var_expr_list)
+    typecheck_ast_list(function, node->expression_stmt.var_expr_list);
+  typecheck_ast_list(function, node->expression_stmt.expr_list);
+
+  if (!node->expression_stmt.var_expr_list)
+    return;
+
+  struct ast_node *var;
+  struct ast_node *expr;
+  PREPARE_PTR_LIST(node->expression_stmt.var_expr_list, var);
+  PREPARE_PTR_LIST(node->local_stmt.expr_list, expr);
+
+  for (;;) {
+    if (!var || !expr)
+      break;
+
+    struct var_type *var_type = &var->common_expr.type;
+    struct var_type *expr_type = &expr->common_expr.type;
+    const char *var_name = ""; // FIXME how do we get this?
+
+    typecheck_var_assignment(var_type, expr_type, var_name);
 
     NEXT_PTR_LIST(var);
     NEXT_PTR_LIST(expr);
   }
 }
 
+
 /* Type checker - WIP  */
 static void typecheck_ast_node(struct ast_node *function, struct ast_node *node) {
   switch (node->type) {
@@ -248,6 +302,7 @@ static void typecheck_ast_node(struct ast_node *function, struct ast_node *node)
       break;
     }
     case AST_EXPR_STMT: {
+      typecheck_expr_statement(function, node);
       break;
     }
     case AST_IF_STMT: {