[ fix #1742 ] Do not use uppercase names as pattern variables (#2642)

src/TTImp/Utils.idr

@@ -635,7 +635,10 @@ getArgName defs x bound allvars ty
     findNames nf = pure $ filter notBound $ fromMaybe defaultNames !(findNamesM nf)
 
     getName : Name -> List String -> List Name -> String
-    getName (UN (Basic n)) defs used = unique (n :: defs) (n :: defs) 0 used
+    getName (UN (Basic n)) defs used =
+      -- # 1742 Uppercase names are not valid for pattern variables
+      let candidate = ifThenElse (lowerFirst n) n (toLower n) in
+      unique (candidate :: defs) (candidate :: defs) 0 used
     getName _ defs used = unique defs defs 0 used
 
 export

tests/Main.idr

@@ -107,7 +107,8 @@ idrisTestsInteractive = MkTestPool "Interactive editing" [] Nothing
        "interactive029", "interactive030", "interactive031", "interactive032",
        "interactive033", "interactive034", "interactive035", "interactive036",
        "interactive037", "interactive038", "interactive039", "interactive040",
-       "interactive041", "interactive042", "interactive043", "interactive044"]
+       "interactive041", "interactive042", "interactive043", "interactive044",
+       "interactive045"]
 
 idrisTestsInterface : TestPool
 idrisTestsInterface = MkTestPool "Interface" [] Nothing

tests/idris2/interactive045/Issue1742.idr

@@ -0,0 +1,5 @@
+data Foo : Type where
+  MkFoo : (Bar : Bool) -> Foo
+
+Gnu : Foo -> Nat
+Gnu x = ?Gnu_rhs_0

tests/idris2/interactive045/expected

@@ -0,0 +1,4 @@
+1/1: Building Issue1742Gen (Issue1742Gen.idr)
+Main> Gnu (MkFoo bar) = ?Gnu_rhs_1
+Main> Loaded file Issue1742Gen.idr
+Main> Bye for now!

tests/idris2/interactive045/input

@@ -0,0 +1,3 @@
+:cs 5 4 x
+:r
+:q

tests/idris2/interactive045/run

@@ -0,0 +1,8 @@
+rm -rf build
+rm -f Issue1742Gen.idr
+
+cp Issue1742.idr Issue1742Gen.idr
+
+$1 --no-color --console-width 0 --no-banner Issue1742Gen.idr < input
+
+rm Issue1742Gen.idr