Merge pull request #3565 from ncave/rust

[Rust] Fixed recursive lambda captured idents cloning
fable-compiler · Oct 24, 2023 · 4af4c49 · 4af4c49
2 parents d60e3a9 + 7ad8c48
commit 4af4c49
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diff --git a/src/Fable.Cli/CHANGELOG.md b/src/Fable.Cli/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+#### Rust
+
+* Fixed recursive lambda captured idents cloning (by @ncave)
+
 ## 4.4.0 - 2023-10-24
 
 ### Changed

diff --git a/src/Fable.Transforms/Rust/Fable2Rust.fs b/src/Fable.Transforms/Rust/Fable2Rust.fs
@@ -3269,7 +3269,6 @@ module Util =
                 makeLibCall com ctx None "Native" ("fix" + argCount) fixCallArgs
             else
                 fnBody
-        let closureExpr = mkClosureExpr true fnDecl fnBody
         let cloneStmts =
             // clone captured idents (in move closures)
             // skip non-local idents (e.g. module let bindings)
@@ -3283,8 +3282,16 @@ module Util =
                 letExpr |> mkSemiStmt)
             |> Seq.toList
         let closureExpr =
-            if List.isEmpty cloneStmts then closureExpr
-            else mkStmtBlockExpr (cloneStmts @ [closureExpr |> mkExprStmt])
+            if List.isEmpty cloneStmts then
+                mkClosureExpr true fnDecl fnBody
+            else
+                let fnBody =
+                    // additional captured idents cloning for recursive lambdas
+                    if isRecursive && not isTailRec then
+                        mkStmtBlockExpr (cloneStmts @ [fnBody |> mkExprStmt])
+                    else fnBody
+                let closureExpr = mkClosureExpr true fnDecl fnBody
+                mkStmtBlockExpr (cloneStmts @ [closureExpr |> mkExprStmt])
         let funcWrap = getLibraryImportName com ctx "Native" ("Func" + argCount)
         makeCall [funcWrap; "new"] None [closureExpr]