Fix #15550 by quoting RULE names during TH conversion

Summary:
When converting a `RuleP` to a GHC source `RuleD` during TH
conversion, we were stupidly not double-quoting the name of the rule.
Easily fixed.

Test Plan: make test TEST=T15550

Reviewers: goldfire, bgamari, simonpj

Reviewed By: simonpj

Subscribers: simonpj, rwbarton, carter

GHC Trac Issues: #15550

Differential Revision: https://phabricator.haskell.org/D5090

compiler/hsSyn/Convert.hs

@@ -705,8 +705,8 @@ cvtPragmaD (RuleP nm bndrs lhs rhs phases)
        ; rhs'   <- cvtl rhs
        ; returnJustL $ Hs.RuleD noExt
             $ HsRules noExt (SourceText "{-# RULES")
-                      [noLoc $ HsRule noExt (noLoc (SourceText nm,nm')) act
-                                                  bndrs' lhs' rhs']
+                      [noLoc $ HsRule noExt (noLoc (quotedSourceText nm,nm'))
+                                                  act bndrs' lhs' rhs']
        }
 
 cvtPragmaD (AnnP target exp)

testsuite/tests/th/T15550.hs

+{-# LANGUAGE TemplateHaskell #-}
+module T15550 where
+
+$([d| myId :: a -> a
+      myId x = x
+      {-# NOINLINE [1] myId #-}
+      {-# RULES "myId" forall x. myId x = x #-}
+    |])

testsuite/tests/th/T15550.stderr

+T15550.hs:(4,3)-(8,6): Splicing declarations
+    [d| {-# RULES "myId" forall x. myId x = x #-}
+        
+        myId :: a -> a
+        myId x = x
+        {-# NOINLINE [1] myId #-} |]
+  ======>
+    myId :: a -> a
+    myId x = x
+    {-# NOINLINE [1] myId #-}
+    {-# RULES "myId" forall x. myId x = x #-}

testsuite/tests/th/all.T

@@ -425,4 +425,5 @@ test('T14471', normal, compile, [''])
 test('TH_rebindableAdo', normal, compile, [''])
 test('T14627', normal, compile_fail, [''])
 test('TH_invalid_add_top_decl', normal, compile_fail, [''])
+test('T15550', normal, compile, ['-v0 -ddump-splices -dsuppress-uniques'])
 test('T15518', normal, compile, ['-v0 -ddump-splices -dsuppress-uniques'])