Annotate the no-return from die()

In all crates we are using a die() function to print to stderr and quit
with a exit status > 0. Apparently in Rust you can annotate the return
type with a bang just like the noreturn from the C family.

The added bonus is that some useless statements to make the compiler
happy without it can be removed altogether as now the compiler is able
to understand that it won't return so the returned type is not needed.

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

1 files changed, 13 insertions, 22 deletions

diff --git a/crates/nasm/src/main.rs b/crates/nasm/src/main.rs
index 010e7d5..a5c446f 100644
--- a/crates/nasm/src/main.rs
+++ b/crates/nasm/src/main.rs
@@ -77,7 +77,6 @@ fn parse_define(arg: &str) -> (String, u8) {
 
     let Some(name) = key_value.next() else {
         die(format!("bad format for define '{arg}'"));
-        return (String::default(), 0);
     };
 
     if name
@@ -95,7 +94,6 @@ fn parse_define(arg: &str) -> (String, u8) {
             die(format!(
                 "value for define '{arg}' must be a valid 8-bit integer"
             ));
-            return (String::default(), 0);
         }
     };
 
@@ -189,7 +187,7 @@ fn parse_arguments() -> Args {
 }
 
 // Print the given `message` and exit(1).
-fn die(message: String) {
+fn die(message: String) -> ! {
     eprintln!("error: {message}");
     std::process::exit(1);
 }
@@ -222,7 +220,7 @@ fn get_directory_from_source(source: &SourceInfo) -> PathBuf {
 // Save the `memory` object into the `<source>/.nasm/memory.txt` file.
 fn save_memory_stats(source: &SourceInfo, memory: &mut MemoryResult, has_working_ram: bool) {
     let Ok(mut file) = File::create(get_directory_from_source(source).join("memory.txt")) else {
-        return die("could not write memory.txt file".to_string());
+        die("could not write memory.txt file".to_string());
     };
 
     let ranges = &mut memory.memory_ranges;
@@ -231,15 +229,15 @@ fn save_memory_stats(source: &SourceInfo, memory: &mut MemoryResult, has_working
     for mr in ranges {
         if mr.range.start + 1 == mr.range.end {
             if let Err(e) = writeln!(file, "{}: {}", mr.to_human(), mr.name) {
-                return die(format!("could not write memory.txt file: {e}"));
+                die(format!("could not write memory.txt file: {e}"));
             }
         } else if let Err(e) = writeln!(file, "{}: {}", mr.to_human(), mr.name) {
-            return die(format!("could not write memory.txt file: {e}"));
+            die(format!("could not write memory.txt file: {e}"));
         }
     }
 
     if let Err(e) = writeln!(file, "\n--- Summary (in bytes) ---") {
-        return die(format!("could not write memory.txt file: {e}"));
+        die(format!("could not write memory.txt file: {e}"));
     }
     print_memory_summary(Box::new(file), memory, has_working_ram);
 }
@@ -255,7 +253,7 @@ fn print_memory_summary(mut output: Box<dyn Write>, memory: &MemoryResult, has_w
         "- Internal RAM: {}/2048 ({:.2}%)",
         memory.total_internal_ram, perc
     ) {
-        return die(format!("could not write memory summary: {e}"));
+        die(format!("could not write memory summary: {e}"));
     }
 
     if has_working_ram {
@@ -273,13 +271,13 @@ fn print_memory_summary(mut output: Box<dyn Write>, memory: &MemoryResult, has_w
 // Save the 'addresses' list into the `<source>/.nasm/addresses.txt` file.
 fn save_addresses(source: &SourceInfo, mut addresses: Vec<xixanta::assembler::Range>) {
     let Ok(mut file) = File::create(get_directory_from_source(source).join("addresses.txt")) else {
-        return die("could not write memory.txt file".to_string());
+        die("could not write memory.txt file".to_string());
     };
 
     addresses.sort_by_key(|a| a.range.start);
     for a in addresses {
         if let Err(e) = writeln!(file, "{},{:04X},{:04X}", a.name, a.range.start, a.range.end) {
-            return die(format!("could not write addresses.txt file: {e}"));
+            die(format!("could not write addresses.txt file: {e}"));
         }
     }
 }
@@ -296,14 +294,14 @@ fn print_segments_stats(mut output: Box<dyn Write>, mappings: &[Mapping]) {
                 "- {}: {}/{} ({:.0}%)",
                 mapping.name, mapping.offset, mapping.size, perc
             ) {
-                return die(format!("could not write segments summary: {e}"));
+                die(format!("could not write segments summary: {e}"));
             }
         } else if let Err(e) = writeln!(
             output,
             "- {}: {}/{} ({:.2}%)",
             mapping.name, mapping.offset, mapping.size, perc
         ) {
-            return die(format!("could not write segments summary: {e}"));
+            die(format!("could not write segments summary: {e}"));
         }
     }
 }
@@ -315,17 +313,13 @@ fn main() {
     let path = Path::new(&args.file);
     let Ok(input) = File::open(path) else {
         die(format!("failed to open the given file '{}'", args.file));
-        return;
     };
     let source = match path.parent() {
         Some(parent) => SourceInfo {
             directory: parent.to_path_buf(),
             name: path.file_name().unwrap().to_str().unwrap().to_string(),
         },
-        None => {
-            die("failed to find directory for the given file".to_string());
-            return;
-        }
+        None => die("failed to find directory for the given file".to_string()),
     };
 
     // Select the output stream.
@@ -337,10 +331,7 @@ fn main() {
         let name = args.out.unwrap_or(String::from("out.nes"));
         match File::create(&name) {
             Ok(f) => (BufWriter::new(Box::new(f)), args.file.as_str()),
-            Err(_) => {
-                die(format!("could not create file '{name}'"));
-                return;
-            }
+            Err(_) => die(format!("could not create file '{name}'")),
         }
     };
 
@@ -455,7 +446,7 @@ fn main() {
         if args.info {
             let Ok(file) = File::create(get_directory_from_source(&source).join("segments.txt"))
             else {
-                return die("could not write segments.txt file".to_string());
+                die("could not write segments.txt file".to_string());
             };
             print_segments_stats(Box::new(file), &res.mappings);
         }