firmware: fix not(has_spiflash) build

artiq/firmware/libboard_misoc/config.rs

@@ -7,7 +7,8 @@ pub enum Error {
     Truncated { offset: usize },
     InvalidSize { offset: usize, size: usize },
     MissingSeparator { offset: usize },
-    Utf8Error(str::Utf8Error)
+    Utf8Error(str::Utf8Error),
+    NoFlash,
 }
 
 impl fmt::Display for Error {
@@ -24,11 +25,23 @@ impl fmt::Display for Error {
             &Error::MissingSeparator { offset } =>
                 write!(f, "missing separator at offset {}", offset),
             &Error::Utf8Error(err) =>
-                write!(f, "{}", err)
+                write!(f, "{}", err),
+            &Error::NoFlash =>
+                write!(f, "flash memory is not present"),
         }
     }
 }
 
+#[cfg(has_spiflash)]
+mod imp {
+    use core::str;
+    use byteorder::{ByteOrder, BigEndian};
+    use cache;
+    use spiflash;
+    use super::Error;
+    use core::fmt;
+    use core::fmt::Write;
+
     struct FmtWrapper<'a> {
         buf: &'a mut [u8],
         offset: usize,
@@ -58,16 +71,6 @@ impl<'a> fmt::Write for FmtWrapper<'a> {
         }
     }
 
-#[cfg(has_spiflash)]
-mod imp {
-    use core::str;
-    use byteorder::{ByteOrder, BigEndian};
-    use cache;
-    use spiflash;
-    use super::Error;
-    use core::fmt::Write;
-    use super::FmtWrapper;
-
     // One flash sector immediately before the firmware.
     const ADDR: usize = ::mem::FLASH_BOOT_ADDRESS - spiflash::SECTOR_SIZE;
     const SIZE: usize = spiflash::SECTOR_SIZE;
@@ -284,24 +287,26 @@ mod imp {
 
 #[cfg(not(has_spiflash))]
 mod imp {
+    use super::Error;
+
     pub fn read<F: FnOnce(Result<&[u8], Error>) -> R, R>(_key: &str, f: F) -> R {
-        f(Err(()))
+        f(Err(Error::NoFlash))
     }
 
     pub fn read_str<F: FnOnce(Result<&str, Error>) -> R, R>(_key: &str, f: F) -> R {
-        f(Err(()))
+        f(Err(Error::NoFlash))
     }
 
     pub fn write(_key: &str, _value: &[u8]) -> Result<(), Error> {
-        Err(())
+        Err(Error::NoFlash)
     }
 
     pub fn remove(_key: &str) -> Result<(), Error> {
-        Err(())
+        Err(Error::NoFlash)
     }
 
     pub fn erase() -> Result<(), Error> {
-        Err(())
+        Err(Error::NoFlash)
     }
 }