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10f06163

by Cheng Shao at 2025-08-25T14:30:16-04:00

wasm: ensure setKeepCAFs() is called in ghci

This patch is a critical bugfix for #26106, see comment and linked
issue for details.

@@ -1105,6 +1105,20 @@ class DyLD {
        if (/libHSghc-internal-\d+(\.\d+)*/i.test(soname)) {
          this.rts_init();
          delete this.rts_init;
++
 +        // At this point the RTS symbols in linear memory are fixed
 +        // and constructors are run, especially the one in JSFFI.c
 +        // that does GHC RTS initialization for any code that links
 +        // JSFFI.o. Luckily no Haskell computation or gc has taken
 +        // place yet, so we must set keepCAFs=1 right now! Otherwise,
 +        // any BCO created by later TH splice or ghci expression may
 +        // refer to any CAF that's not reachable from GC roots (here
 +        // our only entry point is defaultServer) and the CAF could
 +        // have been GC'ed! (#26106)
 +        //
 +        // We call it here instead of in RTS C code, since we only
 +        // want keepCAFs=1 for ghci, not user code.
 +        this.exportFuncs.setKeepCAFs();
+       }
        init();
+     }