Remove BaseFormatter::fbstr()

Summary: Remove `BaseFormatter::fbstr()` because it is virtually unused and those few cases that do use it are better off with `std::string`.

Reviewed By: yfeldblum

Differential Revision: D26358276

fbshipit-source-id: e96b4958735b3c9c03010e1e3dcdd01abd2d6a33

folly/Format-inl.h

@@ -385,7 +385,7 @@ void formatFormatter(
       arg.align != FormatArg::Align::DEFAULT) {
     // We can only avoid creating a temporary string if we align left,
     // as we'd need to know the size beforehand otherwise
-    format_value::formatString(formatter.fbstr(), arg, cb);
+    format_value::formatString(formatter.str(), arg, cb);
   } else {
     auto fn = [&arg, &cb](StringPiece sp) mutable {
       int sz = static_cast<int>(sp.size());

folly/Format.h

@@ -97,15 +97,6 @@ class BaseFormatter {
     return s;
   }
 
-  /**
-   * Conversion to fbstring
-   */
-  fbstring fbstr() const {
-    fbstring s;
-    appendTo(s);
-    return s;
-  }
-
   /**
    * Metadata to identify generated children of BaseFormatter
    */

folly/docs/Format.md

@@ -95,7 +95,7 @@ std::cout << format("{0:05d} decimal = {0:04x} hex", 42);
 
 // Formatter objects may be written to a string using folly::to or
 // folly::toAppend (see folly/Conv.h), or by calling their appendTo(),
-// str(), and fbstr() methods
+// and str() methods
 std::string s = format("The only answer is {}", 42).str();
 std::cout << s;
 // => "The only answer is 42"

folly/test/FormatBenchmark.cpp

@@ -178,8 +178,8 @@ BENCHMARK_RELATIVE(format_nested_fbstrings, iters) {
         format(
             &out,
             "{} {}",
-            format("{} {}", i, i + 1).fbstr(),
-            format("{} {}", -i, -i - 1).fbstr());
+            format("{} {}", i, i + 1).str(),
+            format("{} {}", -i, -i - 1).str());
       });
     }
   }