fix boolean precedence

Summary:
The tree-sitter grammar does not properly reflect the erlang precedence rules for binary operations.

The key changes are that we initially misunderstood the priority allocations, so it is reversed, and most importantly `orelse` and `andalso` had the highest, rather than lowest priority.

This diff aligns it with the erlc compiler, for both precedence and associativity.

Reviewed By: TD5

Differential Revision: D70894827

fbshipit-source-id: ebcb3321448e89876806618d1611e931cb2d95de

Author: alanz

grammar.js

@@ -20,16 +20,37 @@ const PREC = {
     DCOLON: 1, // `::`
     PIPE: 2, // `|`
     EQ: 3, // `=` in Expr
-    PREFIX_OP: 4, // prefix op binds directly to its argument
-    MULT_OP: 5, // mult_op is left-associative
-    ADD_OP: 5, // add_op is left-associative
+
     DOTDOT: 6, // `..` in Type
     DARROW: 7, // `=>` in Type, Expr
-    BANG: 13, // `!` in Expr
-    ORELSE: 14, // `orelse` in Expr
-    ANDALSO: 15, // `andalso` in Expr
-    LIST_OP: 16, // `++` / `--` in Expr
+
+
+    // Binary op precedences
+    // see https://www.erlang.org/doc/system/expressions.html#operator-precedence
+    //
+    // Listed in descending order of precedence
+    //  - so earlier entries should have higher tree-sitter precedence
+    // Operator                     | Association
+    // #                            |
+    // Unary + - bnot not           | PREFIX_OP |
+    // / * div rem band and         | MULT_OP   | Left-associative
+    // + - bor bxor bsl bsr or xor  | ADD_OP    | Left-associative
+    // ++ --                        | LIST_OP   | Right-associative
+    // == /= =< < >= > =:= =/=      | COMP_OP   | Non-associative
+    // andalso                      | ANDALSO   | Left-associative
+    // orelse                       | ORELSE    | Left-associative
+    // catch                        |
+    // = !                          | EQ, BANG  | Right-associative
+    // ?=                           | Non-associative
+
+    PREFIX_OP: 21, // prefix op binds directly to its argument
+    MULT_OP: 20, // mult_op is left-associative
+    ADD_OP: 19, // add_op is left-associative
+    LIST_OP: 18, // `++` / `--` in Expr
     COMP_OP: 17, // Comparison operators in Expr
+    ANDALSO: 15, // `andalso` in Expr
+    ORELSE: 14, // `orelse` in Expr
+    BANG: 13, // `!` in Expr
 
     // For remote vs binary :
     REMOTE: 1,
@@ -541,18 +562,20 @@ module.exports = grammar({
                 '?=',
                 field("rhs", prec.right($._expr)),
             )),
+
+        // https://www.erlang.org/doc/system/expressions.html#operator-precedence
         binary_op_expr: $ => choice(
             prec.right(PREC.BANG, seq(
                 field("lhs", $._expr),
                 '!',
                 field("rhs", $._expr),
             )),
-            prec.right(PREC.ORELSE, seq(
+            prec.left(PREC.ORELSE, seq(
                 field("lhs", $._expr),
                 'orelse',
                 field("rhs", $._expr),
             )),
-            prec.right(PREC.ANDALSO, seq(
+            prec.left(PREC.ANDALSO, seq(
                 field("lhs", $._expr),
                 'andalso',
                 field("rhs", $._expr),