Replace byte slices with str

compiler/gen_wasm/src/backend.rs

@@ -1,5 +1,4 @@
-use bumpalo::{self, collections::Vec};
-use std::fmt::Write;
+use bumpalo::collections::{String, Vec};
 
 use code_builder::Align;
 use roc_builtins::bitcode::{FloatWidth, IntWidth};
@@ -90,16 +89,18 @@ impl<'a> WasmBackend<'a> {
 
         // The preloaded binary has a global to tell us where its data section ends
         // Note: We need this to account for zero data (.bss), which doesn't have an explicit DataSegment!
-        let data_end_name = "__data_end".as_bytes();
         let data_end_idx = app_exports
             .iter()
-            .find(|ex| ex.name == data_end_name)
+            .find(|ex| ex.name == "__data_end")
             .map(|ex| ex.index)
             .unwrap_or_else(|| {
                 internal_error!("Preloaded Wasm binary must export global constant `__data_end`")
             });
         // TODO: move this to module parsing
-        let next_constant_addr = module.global.parse_u32_at_index(data_end_idx).unwrap_or_else(|e| {
+        let next_constant_addr = module
+            .global
+            .parse_u32_at_index(data_end_idx)
+            .unwrap_or_else(|e| {
                 internal_error!("Failed to parse __data_end from object file: {:?}", e);
             });
 
@@ -145,6 +146,7 @@ impl<'a> WasmBackend<'a> {
             .layout_ids
             .get_toplevel(symbol, &layout)
             .to_symbol_string(symbol, self.interns);
+        let name = String::from_str_in(&name, self.env.arena).into_bump_str();
 
         self.proc_lookup.push(ProcLookupData {
             name: symbol,
@@ -302,10 +304,8 @@ impl<'a> WasmBackend<'a> {
             .unwrap();
         let wasm_fn_index = self.fn_index_offset + proc_index as u32;
 
-        let mut debug_name = bumpalo::collections::String::with_capacity_in(64, self.env.arena);
-        write!(debug_name, "{:?}", sym).unwrap();
-        let name_bytes = debug_name.into_bytes().into_bump_slice();
-        self.module.names.append_function(wasm_fn_index, name_bytes);
+        let name = String::from_str_in(sym.as_str(self.interns), self.env.arena).into_bump_str();
+        self.module.names.append_function(wasm_fn_index, name);
     }
 
     /// Build a wrapper around a Roc procedure so that it can be called from our higher-order Zig builtins.
@@ -952,10 +952,11 @@ impl<'a> WasmBackend<'a> {
             .layout_ids
             .get(sym, &Layout::Builtin(Builtin::Str))
             .to_symbol_string(sym, self.interns);
+        let name = String::from_str_in(&name, self.env.arena).into_bump_str();
 
         let linker_symbol = SymInfo::Data(DataSymbol::Defined {
             flags: 0,
-            name: name.clone(),
+            name,
             segment_index,
             segment_offset: 4,
             size: bytes.len() as u32,
@@ -1102,7 +1103,7 @@ impl<'a> WasmBackend<'a> {
         num_wasm_args: usize,
         has_return_val: bool,
     ) {
-        let fn_index = self.module.names.functions[name.as_bytes()];
+        let fn_index = self.module.names.functions[name];
         self.called_preload_fns.push(fn_index);
         let linker_symbol_index = u32::MAX;
 

compiler/gen_wasm/src/lib.rs

@@ -8,7 +8,8 @@ pub mod wasm_module;
 pub mod wasm32_result;
 pub mod wasm32_sized;
 
-use bumpalo::{self, collections::Vec, Bump};
+use bumpalo::collections::{String, Vec};
+use bumpalo::{self, Bump};
 
 use roc_collections::all::{MutMap, MutSet};
 use roc_module::low_level::LowLevelWrapperType;
@@ -58,7 +59,7 @@ pub fn build_module<'a>(
     interns: &'a mut Interns,
     preload_bytes: &[u8],
     procedures: MutMap<(Symbol, ProcLayout<'a>), Proc<'a>>,
-) -> Result<std::vec::Vec<u8>, String> {
+) -> Result<std::vec::Vec<u8>, std::string::String> {
     let (mut wasm_module, called_preload_fns, _) =
         build_module_unserialized(env, interns, preload_bytes, procedures)
             .map_err(|e| format!("{:?}", e))?;
@@ -102,17 +103,18 @@ pub fn build_module_unserialized<'a>(
         let fn_name = layout_ids
             .get_toplevel(sym, &proc_layout)
             .to_symbol_string(sym, interns);
+        let name = String::from_str_in(&fn_name, env.arena).into_bump_str();
 
         if env.exposed_to_host.contains(&sym) {
             maybe_main_fn_index = Some(fn_index);
             exports.push(Export {
-                name: env.arena.alloc_slice_copy(fn_name.as_bytes()),
+                name,
                 ty: ExportType::Func,
                 index: fn_index,
             });
         }
 
-        let linker_sym = SymInfo::for_function(fn_index, fn_name);
+        let linker_sym = SymInfo::for_function(fn_index, name);
         let linker_sym_index = linker_symbols.len() as u32;
 
         // linker_sym_index is redundant for these procs from user code, but needed for generated helpers!

compiler/gen_wasm/src/wasm32_result.rs

@@ -22,7 +22,7 @@ pub trait Wasm32Result {
     fn insert_wrapper<'a>(
         arena: &'a Bump,
         module: &mut WasmModule<'a>,
-        wrapper_name: &str,
+        wrapper_name: &'static str,
         main_function_index: u32,
     ) {
         insert_wrapper_metadata(arena, module, wrapper_name);
@@ -38,7 +38,7 @@ pub trait Wasm32Result {
 pub fn insert_wrapper_for_layout<'a>(
     arena: &'a Bump,
     module: &mut WasmModule<'a>,
-    wrapper_name: &str,
+    wrapper_name: &'static str,
     main_fn_index: u32,
     layout: &Layout<'a>,
 ) {
@@ -84,7 +84,11 @@ pub fn insert_wrapper_for_layout<'a>(
     }
 }
 
-fn insert_wrapper_metadata<'a>(arena: &'a Bump, module: &mut WasmModule<'a>, wrapper_name: &str) {
+fn insert_wrapper_metadata<'a>(
+    arena: &'a Bump,
+    module: &mut WasmModule<'a>,
+    wrapper_name: &'static str,
+) {
     let index = module.import.function_count
         + module.code.preloaded_count
         + module.code.code_builders.len() as u32;
@@ -95,7 +99,7 @@ fn insert_wrapper_metadata<'a>(arena: &'a Bump, module: &mut WasmModule<'a>, wra
     });
 
     module.export.append(Export {
-        name: arena.alloc_slice_copy(wrapper_name.as_bytes()),
+        name: wrapper_name,
         ty: ExportType::Func,
         index,
     });
@@ -103,7 +107,7 @@ fn insert_wrapper_metadata<'a>(arena: &'a Bump, module: &mut WasmModule<'a>, wra
     let linker_symbol = SymInfo::Function(WasmObjectSymbol::Defined {
         flags: 0,
         index,
-        name: wrapper_name.to_string(),
+        name: wrapper_name,
     });
     module.linking.symbol_table.push(linker_symbol);
 }

compiler/gen_wasm/src/wasm_module/linking.rs

@@ -175,13 +175,13 @@ impl<'a> Serialize for RelocationSection<'a> {
 
 /// Linking metadata for data segments
 #[derive(Debug)]
-pub struct LinkingSegment {
-    pub name: String,
+pub struct LinkingSegment<'a> {
+    pub name: &'a str,
     pub alignment: Align,
     pub flags: u32,
 }
 
-impl Serialize for LinkingSegment {
+impl<'a> Serialize for LinkingSegment<'a> {
     fn serialize<T: SerialBuffer>(&self, buffer: &mut T) {
         buffer.encode_u32(self.name.len() as u32);
         buffer.append_slice(self.name.as_bytes());
@@ -238,7 +238,7 @@ impl Serialize for ComdatSym {
 #[allow(dead_code)]
 #[derive(Debug)]
 pub struct LinkingComdat<'a> {
-    name: String,
+    name: &'a str,
     flags: u32,
     syms: Vec<'a, ComdatSym>,
 }
@@ -292,11 +292,11 @@ pub const WASM_SYM_EXPLICIT_NAME: u32 = 0x40; // use the name from the symbol ta
 pub const WASM_SYM_NO_STRIP: u32 = 0x80;
 
 #[derive(Clone, Debug)]
-pub enum WasmObjectSymbol {
+pub enum WasmObjectSymbol<'a> {
     Defined {
         flags: u32,
         index: u32,
-        name: String,
+        name: &'a str,
     },
     Imported {
         flags: u32,
@@ -304,7 +304,7 @@ pub enum WasmObjectSymbol {
     },
 }
 
-impl Serialize for WasmObjectSymbol {
+impl<'a> Serialize for WasmObjectSymbol<'a> {
     fn serialize<T: SerialBuffer>(&self, buffer: &mut T) {
         match self {
             Self::Defined { flags, index, name } => {
@@ -322,21 +322,21 @@ impl Serialize for WasmObjectSymbol {
 }
 
 #[derive(Clone, Debug)]
-pub enum DataSymbol {
+pub enum DataSymbol<'a> {
     Defined {
         flags: u32,
-        name: String,
+        name: &'a str,
         segment_index: u32,
         segment_offset: u32,
         size: u32,
     },
     Imported {
         flags: u32,
-        name: String,
+        name: &'a str,
     },
 }
 
-impl Serialize for DataSymbol {
+impl<'a> Serialize for DataSymbol<'a> {
     fn serialize<T: SerialBuffer>(&self, buffer: &mut T) {
         match self {
             Self::Defined {
@@ -377,17 +377,17 @@ impl Serialize for SectionSymbol {
 }
 
 #[derive(Clone, Debug)]
-pub enum SymInfo {
-    Function(WasmObjectSymbol),
-    Data(DataSymbol),
-    Global(WasmObjectSymbol),
+pub enum SymInfo<'a> {
+    Function(WasmObjectSymbol<'a>),
+    Data(DataSymbol<'a>),
+    Global(WasmObjectSymbol<'a>),
     Section(SectionSymbol),
-    Event(WasmObjectSymbol),
-    Table(WasmObjectSymbol),
+    Event(WasmObjectSymbol<'a>),
+    Table(WasmObjectSymbol<'a>),
 }
 
-impl SymInfo {
-    pub fn for_function(wasm_function_index: u32, name: String) -> Self {
+impl<'a> SymInfo<'a> {
+    pub fn for_function(wasm_function_index: u32, name: &'a str) -> Self {
         SymInfo::Function(WasmObjectSymbol::Defined {
             flags: 0,
             index: wasm_function_index,
@@ -396,7 +396,7 @@ impl SymInfo {
     }
 }
 
-impl Serialize for SymInfo {
+impl<'a> Serialize for SymInfo<'a> {
     fn serialize<T: SerialBuffer>(&self, buffer: &mut T) {
         buffer.append_u8(match self {
             Self::Function(_) => 0,
@@ -459,8 +459,8 @@ const LINKING_VERSION: u8 = 2;
 /// No point writing code to "find" the symbol table, when we know there's exactly one.
 #[derive(Debug)]
 pub struct LinkingSection<'a> {
-    pub symbol_table: Vec<'a, SymInfo>,
-    pub segment_info: Vec<'a, LinkingSegment>,
+    pub symbol_table: Vec<'a, SymInfo<'a>>,
+    pub segment_info: Vec<'a, LinkingSegment<'a>>,
     pub init_funcs: Vec<'a, LinkingInitFunc>,
     pub comdat_info: Vec<'a, LinkingComdat<'a>>,
 }

compiler/gen_wasm/src/wasm_module/parse.rs

@@ -52,15 +52,15 @@ impl Parse<()> for u32 {
     }
 }
 
-// Parse string bytes without utf8 validation
-impl<'a> Parse<&'a Bump> for &'a [u8] {
+impl<'a> Parse<&'a Bump> for &'a str {
     fn parse(arena: &'a Bump, bytes: &[u8], cursor: &mut usize) -> Result<Self, ParseError> {
         let len = u32::parse((), bytes, cursor)?;
         let end = *cursor + len as usize;
         let bytes: &[u8] = &bytes[*cursor..end];
         let copy = arena.alloc_slice_copy(bytes);
+        let s = unsafe { std::str::from_utf8_unchecked(copy) };
         *cursor = end;
-        Ok(copy)
+        Ok(s)
     }
 }
 

compiler/gen_wasm/src/wasm_module/sections.rs

@@ -787,14 +787,14 @@ impl From<u8> for ExportType {
 
 #[derive(Debug)]
 pub struct Export<'a> {
-    pub name: &'a [u8],
+    pub name: &'a str,
     pub ty: ExportType,
     pub index: u32,
 }
 
 impl<'a> Export<'a> {
     fn parse(arena: &'a Bump, bytes: &[u8], cursor: &mut usize) -> Self {
-        let name = <&'a [u8]>::parse(arena, bytes, cursor).unwrap();
+        let name = <&'a str>::parse(arena, bytes, cursor).unwrap();
 
         let ty = ExportType::from(bytes[*cursor]);
         *cursor += 1;
@@ -1257,7 +1257,7 @@ enum NameSubSections {
 
 pub struct NameSection<'a> {
     pub bytes: Vec<'a, u8>,
-    pub functions: MutMap<&'a [u8], u32>,
+    pub functions: MutMap<&'a str, u32>,
 }
 
 impl<'a> NameSection<'a> {
@@ -1268,7 +1268,7 @@ impl<'a> NameSection<'a> {
         self.bytes.len()
     }
 
-    pub fn append_function(&mut self, index: u32, name: &'a [u8]) {
+    pub fn append_function(&mut self, index: u32, name: &'a str) {
         index.serialize(&mut self.bytes);
         name.serialize(&mut self.bytes);
         self.functions.insert(name, index);
@@ -1315,12 +1315,12 @@ impl<'a> NameSection<'a> {
         cursor: &mut usize,
         section_end: usize,
     ) {
-        let section_name = <&'a [u8]>::parse(arena, module_bytes, cursor).unwrap();
-        if section_name != Self::NAME.as_bytes() {
+        let section_name = <&'a str>::parse(arena, module_bytes, cursor).unwrap();
+        if section_name != Self::NAME {
             internal_error!(
                 "Expected Custom section {:?}, found {:?}",
                 Self::NAME,
-                std::str::from_utf8(section_name)
+                section_name
             );
         }
 
@@ -1348,9 +1348,8 @@ impl<'a> NameSection<'a> {
         let fn_names_start = *cursor;
         for _ in 0..num_entries {
             let fn_index = u32::parse((), module_bytes, cursor).unwrap();
-            let name_bytes = <&'a [u8]>::parse(arena, module_bytes, cursor).unwrap();
-            self.functions
-                .insert(arena.alloc_slice_copy(name_bytes), fn_index);
+            let name_bytes = <&'a str>::parse(arena, module_bytes, cursor).unwrap();
+            self.functions.insert(name_bytes, fn_index);
         }
 
         // Copy only the bytes for the function names segment
@@ -1395,8 +1394,7 @@ impl<'a> Debug for NameSection<'a> {
         by_index.sort_unstable();
 
         for (index, name) in by_index.iter() {
-            let name_str = unsafe { std::str::from_utf8_unchecked(name) };
-            writeln!(f, "  {:4}: {}", index, name_str)?;
+            writeln!(f, "  {:4}: {}", index, name)?;
         }
 
         Ok(())

compiler/test_gen/src/helpers/wasm.rs

@@ -120,15 +120,15 @@ fn compile_roc_to_wasm_bytes<'a, T: Wasm32Result>(
     };
 
     let (mut module, called_preload_fns, main_fn_index) =
-        roc_gen_wasm::build_module_unserialized(&env, &mut interns, preload_bytes, procedures).unwrap();
+        roc_gen_wasm::build_module_unserialized(&env, &mut interns, preload_bytes, procedures)
+            .unwrap();
 
     T::insert_wrapper(arena, &mut module, TEST_WRAPPER_NAME, main_fn_index);
 
     // Export the initialiser function for refcount tests
-    let init_refcount_bytes = INIT_REFCOUNT_NAME.as_bytes();
-    let init_refcount_idx = module.names.functions[init_refcount_bytes];
+    let init_refcount_idx = module.names.functions[INIT_REFCOUNT_NAME];
     module.export.append(Export {
-        name: arena.alloc_slice_copy(init_refcount_bytes),
+        name: INIT_REFCOUNT_NAME,
         ty: ExportType::Func,
         index: init_refcount_idx,
     });