From a817e552d75be676670ccbf2d51fae68fd0bfb9f Mon Sep 17 00:00:00 2001
From: Adrian Thurston <thurston@colm.net>
Date: Tue, 1 Oct 2019 09:51:34 -0700
Subject: rust grammar: let needs a pattern on lhs

---
 grammar/rust.lm | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

(limited to 'grammar')

diff --git a/grammar/rust.lm b/grammar/rust.lm
index 929a9a98..e400cce5 100644
--- a/grammar/rust.lm
+++ b/grammar/rust.lm
@@ -1,5 +1,7 @@
 lex
 	literal `fn `use `let `mut `if `struct `for `in
+	literal `true `false
+	literal `ref
 
 	literal `; `:: `( `) `{ `} `. `,
 	literal `[ `] `:
@@ -18,6 +20,9 @@ lex
 	literal `=
 	literal `+= `-= `*= `/= `%= `&= `|= `^= `<<= `>>=
 
+	literal `_
+
+
 	token id /[A-Za-z_] [A-Za-z_0-9]*/
 	token string /'"' ( [^\"] | '\\' any )* '"'/
 	token number /[0-9]+/
@@ -33,6 +38,36 @@ end
 def use_stmt
 	[`use qual_id `;]
 
+#
+# Patterns
+#
+
+def literal_pattern
+	[`true]
+|	[`false]
+|	[string]
+|	[number]
+
+def identifier_pattern
+	[opt_ref opt_mut id]
+
+def pattern_tail
+	[pattern_tail `, pattern]
+|	[]
+
+def pattern
+	[literal_pattern]
+|	[identifier_pattern]
+|	[`_]
+|	[paths `( pattern pattern_tail `)]
+
+def match_arms_pattern_tail
+	[match_arms_pattern_tail `| pattern]
+|	[]
+
+def match_arms_pattern
+	[pattern match_arms_pattern_tail]
+
 #
 # Function declaration
 #
@@ -79,6 +114,10 @@ def opt_mut
 	[`mut]
 |	[]
 
+def opt_ref
+	[`ref]
+|	[]
+
 def opt_type
 	[`: type]
 |	[]
@@ -88,7 +127,7 @@ def let_rvalue
 |	[`{ stmt_list `}]
 
 def let_stmt
-	[`let opt_mut id opt_type `= let_rvalue]
+	[`let pattern opt_type `= let_rvalue]
 
 def expr_tail
 	[expr_tail `, expr]
@@ -127,6 +166,8 @@ def paths
 |	[id `{ cons_list `}]
 |	[ `[ number `; number `]]
 |	[`( `)]
+|	[`true]
+|	[`false]
 
 def func_index
 	[func_index `. qual_id `( expr_list `)]
@@ -246,7 +287,7 @@ def stmt_list
 |	[]
 
 def if_stmt
-	[`if `let expr `= expr `{ stmt_list `} ]
+	[`if `let match_arms_pattern `= expr `{ stmt_list `} ]
 |	[`if expr `{ stmt_list `} ]
 
 def field
-- 
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