Add migration code for f32/f64. (#1364)

* Add migration code for `f32`/`f64`.

Add a `WIT_REQUIRE_F32_F64` environment variable controlling whether
the `float32` and `float64` syntax is acccepted, similar to the
transition for semicolons.

* Enable `float32`/`float64` by default.

crates/wit-component/src/printing.rs

@@ -6,6 +6,7 @@ use wit_parser::*;
 
 // NB: keep in sync with `crates/wit-parser/src/ast/lex.rs`
 const PRINT_SEMICOLONS_DEFAULT: bool = true;
+const PRINT_F32_F64_DEFAULT: bool = false;
 
 /// A utility for printing WebAssembly interface definitions to a string.
 pub struct WitPrinter {
@@ -19,6 +20,7 @@ pub struct WitPrinter {
     emit_docs: bool,
 
     print_semicolons: bool,
+    print_f32_f64: bool,
 }
 
 impl Default for WitPrinter {
@@ -31,6 +33,10 @@ impl Default for WitPrinter {
                 Ok(s) => s == "1",
                 Err(_) => PRINT_SEMICOLONS_DEFAULT,
             },
+            print_f32_f64: match std::env::var("WIT_REQUIRE_F32_F64") {
+                Ok(s) => s == "1",
+                Err(_) => PRINT_F32_F64_DEFAULT,
+            },
         }
     }
 }
@@ -437,8 +443,20 @@ impl WitPrinter {
             Type::S16 => self.output.push_str("s16"),
             Type::S32 => self.output.push_str("s32"),
             Type::S64 => self.output.push_str("s64"),
-            Type::Float32 => self.output.push_str("float32"),
-            Type::Float64 => self.output.push_str("float64"),
+            Type::Float32 => {
+                if self.print_f32_f64 {
+                    self.output.push_str("f32")
+                } else {
+                    self.output.push_str("float32")
+                }
+            }
+            Type::Float64 => {
+                if self.print_f32_f64 {
+                    self.output.push_str("f64")
+                } else {
+                    self.output.push_str("float64")
+                }
+            }
             Type::Char => self.output.push_str("char"),
             Type::String => self.output.push_str("string"),
 

crates/wit-parser/src/ast.rs

@@ -1160,6 +1160,7 @@ pub struct SourceMap {
     sources: Vec<Source>,
     offset: u32,
     require_semicolons: Option<bool>,
+    require_f32_f64: Option<bool>,
 }
 
 #[derive(Clone)]
@@ -1180,6 +1181,11 @@ impl SourceMap {
         self.require_semicolons = Some(enable);
     }
 
+    #[doc(hidden)] // NB: only here for a transitionary period
+    pub fn set_require_f32_f64(&mut self, enable: bool) {
+        self.require_f32_f64 = Some(enable);
+    }
+
     /// Reads the file `path` on the filesystem and appends its contents to this
     /// [`SourceMap`].
     pub fn push_file(&mut self, path: &Path) -> Result<()> {
@@ -1214,8 +1220,13 @@ impl SourceMap {
             let mut srcs = self.sources.iter().collect::<Vec<_>>();
             srcs.sort_by_key(|src| &src.path);
             for src in srcs {
-                let mut tokens = Tokenizer::new(&src.contents, src.offset, self.require_semicolons)
-                    .with_context(|| format!("failed to tokenize path: {}", src.path.display()))?;
+                let mut tokens = Tokenizer::new(
+                    &src.contents,
+                    src.offset,
+                    self.require_semicolons,
+                    self.require_f32_f64,
+                )
+                .with_context(|| format!("failed to tokenize path: {}", src.path.display()))?;
                 let ast = Ast::parse(&mut tokens)?;
                 resolver.push(ast).with_context(|| {
                     format!("failed to start resolving path: {}", src.path.display())
@@ -1324,7 +1335,7 @@ pub(crate) enum AstUsePath {
 }
 
 pub(crate) fn parse_use_path(s: &str) -> Result<AstUsePath> {
-    let mut tokens = Tokenizer::new(s, 0, Some(true))?;
+    let mut tokens = Tokenizer::new(s, 0, Some(true), None)?;
     let path = UsePath::parse(&mut tokens)?;
     if tokens.next()?.is_some() {
         bail!("trailing tokens in path specifier");

crates/wit-parser/src/ast/lex.rs

@@ -13,6 +13,7 @@ pub struct Tokenizer<'a> {
     span_offset: u32,
     chars: CrlfFold<'a>,
     require_semicolons: bool,
+    require_f32_f64: bool,
 }
 
 #[derive(Clone)]
@@ -118,12 +119,14 @@ pub enum Error {
 
 // NB: keep in sync with `crates/wit-component/src/printing.rs`.
 const REQUIRE_SEMICOLONS_BY_DEFAULT: bool = true;
+const REQUIRE_F32_F64_BY_DEFAULT: bool = false;
 
 impl<'a> Tokenizer<'a> {
     pub fn new(
         input: &'a str,
         span_offset: u32,
         require_semicolons: Option<bool>,
+        require_f32_f64: Option<bool>,
     ) -> Result<Tokenizer<'a>> {
         detect_invalid_input(input)?;
 
@@ -139,6 +142,12 @@ impl<'a> Tokenizer<'a> {
                     Err(_) => REQUIRE_SEMICOLONS_BY_DEFAULT,
                 }
             }),
+            require_f32_f64: require_f32_f64.unwrap_or_else(|| {
+                match std::env::var("WIT_REQUIRE_F32_F64") {
+                    Ok(s) => s == "1",
+                    Err(_) => REQUIRE_F32_F64_BY_DEFAULT,
+                }
+            }),
         };
         // Eat utf-8 BOM
         t.eatc('\u{feff}');
@@ -285,8 +294,10 @@ impl<'a> Tokenizer<'a> {
                     "s16" => S16,
                     "s32" => S32,
                     "s64" => S64,
-                    "f32" | "float32" => Float32,
-                    "f64" | "float64" => Float64,
+                    "f32" => Float32,
+                    "f64" => Float64,
+                    "float32" if !self.require_f32_f64 => Float32,
+                    "float64" if !self.require_f32_f64 => Float64,
                     "char" => Char,
                     "resource" => Resource,
                     "own" => Own,
@@ -654,7 +665,7 @@ fn test_validate_id() {
 #[test]
 fn test_tokenizer() {
     fn collect(s: &str) -> Result<Vec<Token>> {
-        let mut t = Tokenizer::new(s, 0, Some(true))?;
+        let mut t = Tokenizer::new(s, 0, Some(true), None)?;
         let mut tokens = Vec::new();
         while let Some(token) = t.next()? {
             tokens.push(token.1);