Instrument float bug

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;

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();
 }
 

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");
+}

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

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)