Merge #99: Fix WASM

7c91cab fix: Debug symbols override each other (Christian Lewe)
439a133 fix: Debug symbol CMRs differ by architecture (Christian Lewe)
81803d4 test: Check that WASM builds in CI (Christian Lewe)
1114654 fix: WASM doesn't build (Christian Lewe)

Pull request description:

  This crate was broken on WASM; make it compile again. Check WASM compilation in CI. Fix broken debug symbols on WASM.

ACKs for top commit:
  apoelstra:
    ACK 7c91cab; successfully ran local tests

Tree-SHA512: d8efa3c62b289db23e17f638218ed7c45e45944971a139eb20b64b3737feeed5f052df0718ed72bd4f22deea93943d50fba00e0324733cb92548761090c83814

.github/workflows/test.yml

@@ -108,3 +108,24 @@ jobs:
     - name: Build each integration test
       run: |
         nix develop .#ci --command bash -c "just build_integration"
+
+  build-wasm:
+    name: Build - WASM
+    runs-on: ubuntu-latest
+    needs: test-stable
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v3
+
+    - name: Install nix
+      uses: cachix/install-nix-action@v24
+      with:
+        github_access_token: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Enable Rust cache
+      uses: Swatinem/rust-cache@v2
+
+    - name: Build WASM library
+      run: |
+        nix develop .#wasm --command bash -c "just build_wasm"

flake.nix

@@ -26,10 +26,11 @@
       pkgs = import nixpkgs {
         inherit system overlays;
       };
-      mkRust = stable: version: profile: extensions: pkgs.rust-bin.${stable}.${version}.${profile}.override {
+      mkRust = stable: version: profile: targets: extensions: pkgs.rust-bin.${stable}.${version}.${profile}.override {
+        inherit targets;
         inherit extensions;
       };
-      defaultRust = mkRust "stable" "latest" "default" ["rust-src"];
+      defaultRust = mkRust "stable" "latest" "default" ["wasm32-unknown-unknown"] ["rust-src"];
       elementsd-simplicity = pkgs.callPackage ./bitcoind-tests/elementsd-simplicity.nix {};
       CC_wasm32_unknown_unknown = "${pkgs.llvmPackages_16.clang-unwrapped}/bin/clang-16";
       AR_wasm32_unknown_unknown = "${pkgs.llvmPackages_16.libllvm}/bin/llvm-ar";
@@ -43,6 +44,9 @@
           ] ++ (
             if with_elements then [ elementsd-simplicity ] else []
           );
+          inherit CC_wasm32_unknown_unknown;
+          inherit AR_wasm32_unknown_unknown;
+          inherit CFLAGS_wasm32_unknown_unknown;
           # Constants for IDE
           RUST_TOOLCHAIN = "${defaultRust}/bin";
           RUST_STDLIB = "${defaultRust}/lib/rustlib/src/rust";
@@ -56,28 +60,33 @@
         # Temporary shells until CI has its nix derivations
         ci = pkgs.mkShell {
           buildInputs = [
-            (mkRust "stable" "latest" "default" [])
+            (mkRust "stable" "latest" "default" [] [])
             pkgs.just
             pkgs.cargo-hack
           ];
         };
         msrv = pkgs.mkShell {
           buildInputs = [
-            (mkRust "stable" "1.63.0" "minimal" [])
+            (mkRust "stable" "1.63.0" "minimal" [] [])
             pkgs.just
           ];
         };
         fuzz = pkgs.mkShell.override {
           stdenv = pkgs.clang16Stdenv;
         } {
           buildInputs = [
-            (mkRust "nightly" "2024-07-01" "minimal" ["llvm-tools-preview"])
+            (mkRust "nightly" "2024-07-01" "minimal" [] ["llvm-tools-preview"])
             pkgs.just
             pkgs.cargo-fuzz
             pkgs.cargo-binutils
             pkgs.rustfilt
           ];
-          # Constants for compiler
+        };
+        wasm = pkgs.mkShell {
+          buildInputs = [
+            (mkRust "stable" "latest" "default" ["wasm32-unknown-unknown"] [])
+            pkgs.just
+          ];
           inherit CC_wasm32_unknown_unknown;
           inherit AR_wasm32_unknown_unknown;
           inherit CFLAGS_wasm32_unknown_unknown;

justfile

@@ -49,6 +49,10 @@ build_fuzz:
 build_integration:
     cargo test --no-run --manifest-path ./bitcoind-tests/Cargo.toml
 
+# Build code for the WASM target
+build_wasm:
+    cargo check --target wasm32-unknown-unknown
+
 # Remove all temporary files
 clean:
     rm -rf target

src/ast.rs

@@ -7,7 +7,7 @@ use either::Either;
 use miniscript::iter::{Tree, TreeLike};
 use simplicity::jet::Elements;
 
-use crate::debug::{DebugSymbols, TrackedCallName};
+use crate::debug::{CallTracker, DebugSymbols, TrackedCallName};
 use crate::error::{Error, RichError, Span, WithSpan};
 use crate::num::{NonZeroPow2Usize, Pow2Usize};
 use crate::parse::MatchPattern;
@@ -39,7 +39,7 @@ impl WitnessTypes {
 pub struct Program {
     main: Expression,
     witness_types: WitnessTypes,
-    tracked_calls: Arc<[(Span, TrackedCallName)]>,
+    call_tracker: Arc<CallTracker>,
 }
 
 impl Program {
@@ -57,11 +57,12 @@ impl Program {
 
     /// Access the debug symbols of the program.
     pub fn debug_symbols(&self, file: &str) -> DebugSymbols {
-        let mut debug_symbols = DebugSymbols::default();
-        for (span, name) in self.tracked_calls.iter() {
-            debug_symbols.insert(*span, name.clone(), file);
-        }
-        debug_symbols
+        self.call_tracker.with_file(file)
+    }
+
+    /// Access the tracker of function calls.
+    pub(crate) fn call_tracker(&self) -> &Arc<CallTracker> {
+        &self.call_tracker
     }
 }
 
@@ -485,7 +486,7 @@ struct Scope {
     witnesses: HashMap<WitnessName, ResolvedType>,
     functions: HashMap<FunctionName, CustomFunction>,
     is_main: bool,
-    tracked_calls: Vec<(Span, TrackedCallName)>,
+    call_tracker: CallTracker,
 }
 
 impl Scope {
@@ -602,9 +603,9 @@ impl Scope {
     /// Consume the scope and return its contents:
     ///
     /// 1. The map that assigns witness names to their expected type.
-    /// 2. The list of tracked function calls.
-    pub fn destruct(self) -> (WitnessTypes, Vec<(Span, TrackedCallName)>) {
-        (WitnessTypes(self.witnesses), self.tracked_calls)
+    /// 2. The function call tracker.
+    pub fn destruct(self) -> (WitnessTypes, CallTracker) {
+        (WitnessTypes(self.witnesses), self.call_tracker)
     }
 
     /// Insert a custom function into the global map.
@@ -633,7 +634,7 @@ impl Scope {
 
     /// Track a call expression with its span.
     pub fn track_call<S: AsRef<Span>>(&mut self, span: &S, name: TrackedCallName) {
-        self.tracked_calls.push((*span.as_ref(), name));
+        self.call_tracker.track_call(*span.as_ref(), name);
     }
 }
 
@@ -660,7 +661,7 @@ impl Program {
             .map(|s| Item::analyze(s, &unit, &mut scope))
             .collect::<Result<Vec<Item>, RichError>>()?;
         debug_assert!(scope.is_topmost());
-        let (witness_types, tracked_calls) = scope.destruct();
+        let (witness_types, call_tracker) = scope.destruct();
         let mut iter = items.into_iter().filter_map(|item| match item {
             Item::Function(Function::Main(expr)) => Some(expr),
             _ => None,
@@ -672,7 +673,7 @@ impl Program {
         Ok(Self {
             main,
             witness_types,
-            tracked_calls: tracked_calls.into_iter().collect(),
+            call_tracker: Arc::new(call_tracker),
         })
     }
 }
@@ -1110,7 +1111,7 @@ impl AbstractSyntaxTree for Call {
                 check_argument_types(from.args(), &args_tys).with_span(from)?;
                 let args = analyze_arguments(from.args(), &args_tys, scope)?;
                 let [arg_ty] = args_tys;
-                scope.track_call(from.args().first().unwrap(), TrackedCallName::Debug(arg_ty));
+                scope.track_call(from, TrackedCallName::Debug(arg_ty));
                 args
             }
             CallName::TypeCast(source) => {