[ruby/json] Adjust fpconv to add ".0" to integers

Adds a test case

fix

https://github.com/ruby/json/commit/fa5bdf87cb

2 files changed, 10 insertions, 13 deletions

diff --git a/ext/json/ext/vendor/fpconv/src/fpconv.c b/ext/json/ext/vendor/fpconv/src/fpconv.c
index 56ebb8944a..8ad80d9c6b 100644
--- a/ext/json/ext/vendor/fpconv/src/fpconv.c
+++ b/ext/json/ext/vendor/fpconv/src/fpconv.c
@@ -222,7 +222,11 @@ static int emit_digits(char* digits, int ndigits, char* dest, int K, bool neg)
         memcpy(dest, digits, ndigits);
         memset(dest + ndigits, '0', K);
 
-        return ndigits + K;
+        /* add a .0 to mark this as a float. */
+        dest[ndigits + K] = '.';
+        dest[ndigits + K + 1] = '0';
+
+        return ndigits + K + 2;
     }
 
     /* write decimal w/o scientific notation */
@@ -290,7 +294,9 @@ static int filter_special(double fp, char* dest)
 {
     if(fp == 0.0) {
         dest[0] = '0';
-        return 1;
+        dest[1] = '.';
+        dest[2] = '0';
+        return 3;
     }
 
     uint64_t bits = get_dbits(fp);
diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index 0f028fe072..6ef16ced8f 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -1084,18 +1084,9 @@ static void generate_json_float(FBuffer *buffer, struct generate_json_data *data
     char* d = buffer->ptr + buffer->len;
     int len = fpconv_dtoa(value, d);
 
-    /* fpconv_dtoa converts a float to its shorted string representation. When
-     * converting a float that is exactly an integer (e.g. `Float(2)`) this
-     * returns in a string that looks like an integer. This is correct, since
-     * JSON treats ints and floats the same. However, to not break integrations
-     * that expect a string representation looking like a float, we append a
-     * "." in that case.
+    /* fpconv_dtoa converts a float to its shortest string representation,
+     * but it adds a ".0" if this is a plain integer.
      */
-    if(!memchr(d, '.', len) && !memchr(d, 'e', len)) {
-        d[len] = '.';
-        d[len+1] = '0';
-        len += 2;
-    }
     buffer->len += len;
 }