Set exceptions for boost::format and remove HintFmt::interpolate

src/libutil/fmt.hh

@@ -29,6 +29,17 @@ inline void formatHelper(F & f, const T & x, const Args & ... args)
     // Interpolate one argument and then recurse.
     formatHelper(f % x, args...);
 }
+
+/**
+ * Set the correct exceptions for `fmt`.
+ */
+void setExceptions(boost::format & fmt)
+{
+    fmt.exceptions(
+        boost::io::all_error_bits ^
+        boost::io::too_many_args_bit ^
+        boost::io::too_few_args_bit);
+}
 }
 
 /**
@@ -68,7 +79,7 @@ template<typename... Args>
 inline std::string fmt(const std::string & fs, const Args & ... args)
 {
     boost::format f(fs);
-    f.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);
+    setExceptions(f);
     formatHelper(f, args...);
     return f.str();
 }
@@ -121,24 +132,6 @@ private:
     boost::format fmt;
 
 public:
-    /**
-     * Construct a `HintFmt` from a format string, with values to be
-     * interpolated later with `%`.
-     *
-     * This isn't exposed as a single-argument constructor to avoid
-     * accidentally constructing `HintFmt`s with user-controlled strings. See
-     * the note on `fmt` for more information.
-     */
-    static HintFmt interpolate(const std::string & formatString)
-    {
-        HintFmt result((boost::format(formatString)));
-        result.fmt.exceptions(
-            boost::io::all_error_bits ^
-            boost::io::too_many_args_bit ^
-            boost::io::too_few_args_bit);
-        return result;
-    }
-
     /**
      * Format the given string literally, without interpolating format
      * placeholders.
@@ -152,18 +145,20 @@ public:
      */
     template<typename... Args>
     HintFmt(const std::string & format, const Args & ... args)
-        : fmt(format)
-    {
-        formatHelper(*this, args...);
-    }
+        : HintFmt(boost::format(format), args...)
+    { }
 
     HintFmt(const HintFmt & hf)
         : fmt(hf.fmt)
     { }
 
-    HintFmt(boost::format && fmt)
+    template<typename... Args>
+    HintFmt(boost::format && fmt, const Args & ... args)
         : fmt(std::move(fmt))
-    { }
+    {
+        setExceptions(fmt);
+        formatHelper(*this, args...);
+    }
 
     template<class T>
     HintFmt & operator%(const T & value)