[Git][ghc/ghc][master] Use lookupOccRn_maybe in TH.lookupName

[Marge Bot (@marge-bot)]

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


Commits:
c5fc7304 by sheaf at 2024-01-15T14:15:29-05:00
Use lookupOccRn_maybe in TH.lookupName

When looking up a value, we want to be able to find both variables
and record fields. So we should not use the lookupSameOccRn_maybe
function, as we can't know ahead of time which record field namespace
a record field with the given textual name will belong to.

Fixes #24293

- - - - -


6 changed files:

- compiler/GHC/Tc/Gen/Splice.hs
- + testsuite/tests/overloadedrecflds/should_compile/T24293.hs
- + testsuite/tests/overloadedrecflds/should_compile/T24293b.hs
- + testsuite/tests/overloadedrecflds/should_compile/T24293c.hs
- + testsuite/tests/overloadedrecflds/should_compile/T24293c.stderr
- testsuite/tests/overloadedrecflds/should_compile/all.T


Changes:

=====================================
compiler/GHC/Tc/Gen/Splice.hs
=====================================
@@ -1944,8 +1944,8 @@ lookupName :: Bool      -- True  <=> type namespace
                         -- False <=> value namespace
            -> String -> TcM (Maybe TH.Name)
 lookupName is_type_name s
-  = do { mb_nm <- lookupSameOccRn_maybe rdr_name
-       ; return (fmap reifyName mb_nm) }
+  = do { mb_nm <- lookupOccRn_maybe rdr_name
+       ; return (fmap (reifyName . greName) mb_nm) }
   where
     th_name = TH.mkName s       -- Parses M.x into a base of 'x' and a module of 'M'
 
@@ -1960,6 +1960,12 @@ lookupName is_type_name s
         | otherwise
         = if isLexCon occ_fs then mkDataOccFS occ_fs
                              else mkVarOccFS  occ_fs
+                               -- NB: when we pick the variable namespace, we
+                               -- might well obtain an identifier in a record
+                               -- field namespace, as lookupOccRn_maybe looks in
+                               -- record field namespaces when looking up variables.
+                               -- This ensures we can look up record fields using
+                               -- this function (#24293).
 
     rdr_name = case TH.nameModule th_name of
                  Nothing  -> mkRdrUnqual occ


=====================================
testsuite/tests/overloadedrecflds/should_compile/T24293.hs
=====================================
@@ -0,0 +1,9 @@
+{-# LANGUAGE TemplateHaskell #-}
+module T24293 where
+import Language.Haskell.TH
+
+data Cheval = Cheval { hibou :: Int }
+
+name = $(do
+  n <- lookupValueName "hibou"
+  pure $ LitE $ StringL $ show n)


=====================================
testsuite/tests/overloadedrecflds/should_compile/T24293b.hs
=====================================
@@ -0,0 +1,13 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE NoFieldSelectors #-}
+module T24293b where
+import Language.Haskell.TH
+
+data Cheval = Cheval { hibou :: Int }
+
+hibou :: Bool
+hibou = False
+
+name = $(do
+  n <- lookupValueName "hibou"
+  pure $ LitE $ StringL $ show n)


=====================================
testsuite/tests/overloadedrecflds/should_compile/T24293c.hs
=====================================
@@ -0,0 +1,11 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+module T24293c where
+import Language.Haskell.TH
+
+data Cheval = Cheval { hibou :: Int }
+data Agneau = Agneau { hibou :: Bool }
+
+name = $(do
+  n <- lookupValueName "hibou"
+  pure $ LitE $ StringL $ show n)


=====================================
testsuite/tests/overloadedrecflds/should_compile/T24293c.stderr
=====================================
@@ -0,0 +1,11 @@
+
+T24293c.hs:9:9: error: [GHC-87543]
+    • Ambiguous occurrence ‘hibou’.
+      It could refer to
+         either the field ‘hibou’ of record ‘Cheval’,
+                defined at T24293c.hs:6:24,
+             or the field ‘hibou’ of record ‘Agneau’,
+                defined at T24293c.hs:7:24.
+    • In the untyped splice:
+        $(do n <- lookupValueName "hibou"
+             pure $ LitE $ StringL $ show n)


=====================================
testsuite/tests/overloadedrecflds/should_compile/all.T
=====================================
@@ -57,3 +57,6 @@ test('T22106_D', [extra_files(['T22106_aux.hs'])], multimod_compile, ['T22106_D'
 test('T22424', req_th, compile, ['-this-unit-id="me"'])
 test('T23279', [extra_files(['T23279_aux.hs'])], multimod_compile, ['T23279', '-v0'])
 test('T23557', [extra_files(['T23557_aux.hs'])], multimod_compile, ['T23557', '-v0'])
+test('T24293', req_th, compile, [''])
+test('T24293b', req_th, compile, [''])
+test('T24293c', req_th, compile_fail, [''])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c5fc7304d56c7a1e0a7bc6e53e23b976772fc10e

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/c5fc7304d56c7a1e0a7bc6e53e23b976772fc10e
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