From 02b924e147458b1c8f6fb8ed3ca2ede955ed37c9 Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Fri, 6 Nov 2020 10:33:57 -0500
Subject: [PATCH] Instrument float bug

---
 ext/liquid_c/lexer.c    |  6 ++++++
 ext/liquid_c/liquid.c   |  2 ++
 ext/liquid_c/usage.c    | 18 ++++++++++++++++++
 ext/liquid_c/usage.h    |  9 +++++++++
 test/unit/block_test.rb | 15 +++++++++++++++
 5 files changed, 50 insertions(+)
 create mode 100644 ext/liquid_c/usage.c
 create mode 100644 ext/liquid_c/usage.h

diff --git a/ext/liquid_c/lexer.c b/ext/liquid_c/lexer.c
index fa5d99c8..3fb351dd 100644
--- a/ext/liquid_c/lexer.c
+++ b/ext/liquid_c/lexer.c
@@ -1,5 +1,6 @@
 #include "liquid.h"
 #include "lexer.h"
+#include "usage.h"
 #include <stdio.h>
 
 const char *symbol_names[TOKEN_END] = {
@@ -107,6 +108,11 @@ const char *lex_one(const char *start, const char *end, lexer_token_t *token)
         }
     }
 
+    // Instrument for bug: https://github.com/Shopify/liquid-c/pull/120
+    if (c == '-' && str + 1 < end && str[1] == '.') {
+        usage_increment("liquid_c_negative_float_without_integer");
+    }
+
     if (ISDIGIT(c) || c == '-') {
         int has_dot = 0;
         cur = str;
diff --git a/ext/liquid_c/liquid.c b/ext/liquid_c/liquid.c
index aebf3231..dc9a2eb8 100644
--- a/ext/liquid_c/liquid.c
+++ b/ext/liquid_c/liquid.c
@@ -10,6 +10,7 @@
 #include "context.h"
 #include "variable_lookup.h"
 #include "vm.h"
+#include "usage.h"
 
 ID id_evaluate;
 ID id_to_liquid;
@@ -82,5 +83,6 @@ void Init_liquid_c(void)
     init_liquid_context();
     init_liquid_variable_lookup();
     init_liquid_vm();
+    init_liquid_usage();
 }
 
diff --git a/ext/liquid_c/usage.c b/ext/liquid_c/usage.c
new file mode 100644
index 00000000..c72f5b72
--- /dev/null
+++ b/ext/liquid_c/usage.c
@@ -0,0 +1,18 @@
+#include "usage.h"
+
+static VALUE cLiquidUsage;
+static ID id_increment;
+
+void usage_increment(const char *name)
+{
+    VALUE name_str = rb_str_new_cstr(name);
+    rb_funcall(cLiquidUsage, id_increment, 1, name_str);
+}
+
+void init_liquid_usage()
+{
+    cLiquidUsage = rb_const_get(mLiquid, rb_intern("Usage"));
+    rb_global_variable(&cLiquidUsage);
+
+    id_increment = rb_intern("increment");
+}
diff --git a/ext/liquid_c/usage.h b/ext/liquid_c/usage.h
new file mode 100644
index 00000000..43e5041b
--- /dev/null
+++ b/ext/liquid_c/usage.h
@@ -0,0 +1,9 @@
+#ifndef LIQUID_USAGE_H
+#define LIQUID_USAGE_H
+
+#include "liquid.h"
+
+void init_liquid_usage();
+void usage_increment(const char *name);
+
+#endif
diff --git a/test/unit/block_test.rb b/test/unit/block_test.rb
index 0b267e87..64381f5b 100644
--- a/test/unit/block_test.rb
+++ b/test/unit/block_test.rb
@@ -31,6 +31,21 @@ def test_op_write_raw_w
     assert_equal(source, template.render!)
   end
 
+  # Test for bug: https://github.com/Shopify/liquid-c/pull/120
+  def test_bug_120_instrument
+    calls = []
+    Liquid::Usage.stub(:increment, ->(name) { calls << name }) do
+      Liquid::Template.parse("{{ -.1 }}")
+    end
+    assert_equal ["liquid_c_negative_float_without_integer"], calls
+
+    calls = []
+    Liquid::Usage.stub(:increment, ->(name) { calls << name }) do
+      Liquid::Template.parse("{{ .1 }}")
+    end
+    assert_equal [], calls
+  end
+
   def test_disassemble_raw_w
     source = "a" * 2**8
     template = Liquid::Template.parse(source)