build: fix nostd tests (m4b#89)

* Add nostd tests
* Fix `cargo test --no-default-features` to pass by making std-only tests/docs conditional (added to CI)
* There are a few `FIXME` in the code where things seemed suspicious

src/leb128.rs

@@ -184,23 +184,23 @@ mod tests {
         let bytes = &buf[..];
         let num = bytes.pread::<Uleb128>(0).unwrap();
         #[cfg(feature = "std")]
-        println!("num: {num:?}");
+        println!("num: {:?}", &num);
         assert_eq!(130u64, num.into());
         assert_eq!(num.size(), 2);
 
         let buf = [0x00, 0x01];
         let bytes = &buf[..];
         let num = bytes.pread::<Uleb128>(0).unwrap();
         #[cfg(feature = "std")]
-        println!("num: {num:?}");
+        println!("num: {:?}", &num);
         assert_eq!(0u64, num.into());
         assert_eq!(num.size(), 1);
 
         let buf = [0x21];
         let bytes = &buf[..];
         let num = bytes.pread::<Uleb128>(0).unwrap();
         #[cfg(feature = "std")]
-        println!("num: {num:?}");
+        println!("num: {:?}", &num);
         assert_eq!(0x21u64, num.into());
         assert_eq!(num.size(), 1);
     }

src/lib.rs

@@ -358,22 +358,22 @@ mod tests {
         let b = &bytes[..];
         let s: &str = b.pread(0).unwrap();
         #[cfg(feature = "std")]
-        println!("str: {s}");
+        println!("str: {}", s);
         assert_eq!(s.len(), bytes[..].len() - 1);
         let bytes: &[u8] = b"hello, world!\0some_other_things";
         let hello_world: &str = bytes.pread_with(0, StrCtx::Delimiter(NULL)).unwrap();
         #[cfg(feature = "std")]
-        println!("{hello_world:?}");
+        println!("{:?}", &hello_world);
         assert_eq!(hello_world.len(), 13);
         let hello: &str = bytes.pread_with(0, StrCtx::Delimiter(SPACE)).unwrap();
         #[cfg(feature = "std")]
-        println!("{hello:?}");
+        println!("{:?}", &hello);
         assert_eq!(hello.len(), 6);
         // this could result in underflow so we just try it
         let _error = bytes.pread_with::<&str>(6, StrCtx::Delimiter(SPACE));
         let error = bytes.pread_with::<&str>(7, StrCtx::Delimiter(SPACE));
         #[cfg(feature = "std")]
-        println!("{error:?}");
+        println!("{:?}", &error);
         assert!(error.is_ok());
     }
 
@@ -383,14 +383,16 @@ mod tests {
         use super::Pread;
         let bytes: &[u8] = b"";
         let hello_world = bytes.pread_with::<&str>(0, StrCtx::Delimiter(NULL));
+        #[cfg(feature = "std")]
         println!("1 {:?}", &hello_world);
         assert!(hello_world.is_err());
         let error = bytes.pread_with::<&str>(7, StrCtx::Delimiter(SPACE));
         #[cfg(feature = "std")]
-        println!("2 {error:?}");
+        println!("2 {:?}", &error);
         assert!(error.is_err());
         let bytes: &[u8] = b"\0";
         let null = bytes.pread::<&str>(0).unwrap();
+        #[cfg(feature = "std")]
         println!("3 {:?}", &null);
         assert!(null.is_empty());
     }
@@ -619,9 +621,10 @@ mod tests {
         let astring: [u8; 3] = [0x45, 0x2a, 0x44];
         let string = astring.gread_with::<&str>(offset, StrCtx::Length(2));
         match &string {
-            &Ok(_) => {}
-            Err(err) => {
-                println!("{}", &err);
+            Ok(_) => {}
+            Err(_err) => {
+                #[cfg(feature = "std")]
+                println!("{_err}");
                 panic!();
             }
         }