Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

• 0bfd29c3
  by Cheng Shao at 2026-03-09T04:54:46-04:00

  wasm: fix `Illegal foreign declaration` failure when ghci loads modules with JSFFI exports
  
  This patch fixes a wasm ghci error when loading modules with JSFFI
  exports; the `backendValidityOfCExport` check in `tcCheckFEType`
  should only makes sense and should be performed when not checking the
  JavaScript calling convention; otherwise, when the calling convention
  is JavaScript, the codegen logic should be trusted to backends that
  actually make use of it. Fixes #26998.
  

3 changed files:

• compiler/GHC/Tc/Gen/Foreign.hs
• + testsuite/tests/ghci-wasm/T26998.hs
• testsuite/tests/ghci-wasm/all.T

Changes:

 tcCheckFEType :: Type -> ForeignExport GhcRn -> TcM (ForeignExport GhcTc)

 tcCheckFEType sig_ty edecl@(CExport src (L l (CExportStatic str cconv))) = do

-    checkCg (Left edecl) backendValidityOfCExport

-    when (cconv /= JavaScriptCallConv) $ checkTc (isCLabelString str) (TcRnInvalidCIdentifier str)

+    when (cconv /= JavaScriptCallConv) $ do

+      checkCg (Left edecl) backendValidityOfCExport

+      checkTc (isCLabelString str) (TcRnInvalidCIdentifier str)

     cconv' <- checkCConv (Left edecl) cconv

     checkForeignArgs isFFIExternalTy arg_tys

     checkForeignRes nonIOok noCheckSafe isFFIExportResultTy res_ty

+main :: IO ()

+main = pure ()

+

+foreign export javascript "my_main" main :: IO ()

   extra_hc_opts('-L. -lT26430B')]

 , compile_and_run, ['']

 )

+

+test('T26998', [], compile_and_run, [''])