diff options
-rw-r--r-- | compiler/GHC/Tc/Gen/Splice.hs | 14 | ||||
-rw-r--r-- | testsuite/tests/th/T20179.hs | 7 | ||||
-rw-r--r-- | testsuite/tests/th/T20179.stderr | 10 | ||||
-rw-r--r-- | testsuite/tests/th/all.T | 1 |
4 files changed, 28 insertions, 4 deletions
diff --git a/compiler/GHC/Tc/Gen/Splice.hs b/compiler/GHC/Tc/Gen/Splice.hs index 998f03a5d5..f2fd31f02a 100644 --- a/compiler/GHC/Tc/Gen/Splice.hs +++ b/compiler/GHC/Tc/Gen/Splice.hs @@ -735,11 +735,17 @@ tcTopSpliceExpr isTypedSplice tc_action -- is expected (#7276) setStage (Splice isTypedSplice) $ do { -- Typecheck the expression - (expr', wanted) <- captureConstraints tc_action - ; const_binds <- simplifyTop wanted + (mb_expr', wanted) <- tryCaptureConstraints tc_action + -- If tc_action fails (perhaps because of insoluble constraints) + -- we want to capture and report those constraints, else we may + -- just get a silent failure (#20179). Hence the 'try' part. - -- Zonk it and tie the knot of dictionary bindings - ; return $ mkHsDictLet (EvBinds const_binds) expr' } + ; const_binds <- simplifyTop wanted + + ; case mb_expr' of + Nothing -> failM -- In this case simplifyTop should have + -- reported some errors + Just expr' -> return $ mkHsDictLet (EvBinds const_binds) expr' } {- ************************************************************************ diff --git a/testsuite/tests/th/T20179.hs b/testsuite/tests/th/T20179.hs new file mode 100644 index 0000000000..a01f573979 --- /dev/null +++ b/testsuite/tests/th/T20179.hs @@ -0,0 +1,7 @@ +{-# LANGUAGE TemplateHaskell #-} +module Bug where + +$(let slurmp :: [Maybe] + slurmp = [] + + in pure []) diff --git a/testsuite/tests/th/T20179.stderr b/testsuite/tests/th/T20179.stderr new file mode 100644 index 0000000000..28eb54d698 --- /dev/null +++ b/testsuite/tests/th/T20179.stderr @@ -0,0 +1,10 @@ + +T20179.hs:4:18: error: + • Expecting one more argument to ‘Maybe’ + Expected a type, but ‘Maybe’ has kind ‘* -> *’ + • In the type signature: slurmp :: [Maybe] + In the expression: + let + slurmp :: [Maybe] + slurmp = [] + in pure [] diff --git a/testsuite/tests/th/all.T b/testsuite/tests/th/all.T index 6d4a5036d7..c89b748f82 100644 --- a/testsuite/tests/th/all.T +++ b/testsuite/tests/th/all.T @@ -513,3 +513,4 @@ test('T18102b', extra_files(['T18102b_aux.hs']), compile_and_run, ['']) test('T18121', normal, compile, ['']) test('T18123', normal, compile, ['']) test('T18388', normal, compile, ['']) +test('T20179', normal, compile_fail, ['']) |