Predef.error surfaces as error message in compilation and cc command

src/compiler/GF/Compile/Compute/Concrete.hs

@@ -12,7 +12,7 @@
 -- Computation of source terms. Used in compilation and in @cc@ command.
 -----------------------------------------------------------------------------
 
-module GF.Compile.Compute.Concrete (computeConcrete, computeTerm,computeConcreteRec) where
+module GF.Compile.Compute.Concrete (computeConcrete, computeTerm,computeConcreteRec,checkPredefError) where
 
 import GF.Data.Operations
 import GF.Grammar.Grammar
@@ -20,6 +20,7 @@ import GF.Infra.Ident
 import GF.Infra.Option
 import GF.Infra.Modules
 import GF.Data.Str
+import GF.Grammar.ShowTerm
 import GF.Grammar.Printer
 import GF.Grammar.Predef
 import GF.Grammar.Macros
@@ -466,3 +467,10 @@ getArgType t = case t of
   V ty _ -> return ty
   T (TComp ty) _ -> return ty
   _ -> Bad (render (text "cannot get argument type of table" $$ nest 2 (ppTerm Unqualified 0 t)))
+
+
+checkPredefError :: SourceGrammar -> Term -> Err Term
+checkPredefError sgr t = case t of
+  App (Q (mod,f)) s | mod == cPredef && f == cError -> Bad $ showTerm sgr TermPrintOne Unqualified s
+  _ -> composOp (checkPredefError sgr) t
+  

src/compiler/GF/Compile/Optimize.hs

@@ -112,7 +112,8 @@ partEval opts gr (context, val) trm = errIn (render (text "partial evaluation" <
   trm3 <- if rightType trm2
             then computeTerm gr subst trm2
             else recordExpand val trm2 >>= computeTerm gr subst
-  return $ mkAbs [(Explicit,v) | v <- vars] trm3
+  trm4 <- checkPredefError gr trm3
+  return $ mkAbs [(Explicit,v) | v <- vars] trm4
   where
     -- don't eta expand records of right length (correct by type checking)
     rightType (R rs) = case val of
@@ -199,3 +200,4 @@ replace old new trm =
     R _      | trm == old -> new
     App x y               -> App (replace old new x) (replace old new y)
     _                     -> composSafeOp (replace old new) trm
+

src/compiler/GFI.hs

@@ -12,7 +12,7 @@ import GF.Grammar hiding (Ident)
 import GF.Grammar.Parser (runP, pExp)
 import GF.Grammar.ShowTerm
 import GF.Compile.Rename
-import GF.Compile.Compute.Concrete (computeConcrete)
+import GF.Compile.Compute.Concrete (computeConcrete,checkPredefError)
 import GF.Compile.TypeCheck.Concrete (inferLType)
 import GF.Infra.Dependencies
 import GF.Infra.CheckM
@@ -124,7 +124,8 @@ loop opts gfenv0 = do
                  mo <- maybe (Bad "no source grammar in scope") return $ greatestResource gr
                  ((t,_),_) <- runCheck $ do t <- renameSourceTerm gr mo t
                                             inferLType gr [] t
-                 computeConcrete sgr t
+                 t1 <- computeConcrete sgr t
+                 checkPredefError sgr t1
 
              case runP pExp (encodeUnicode utf8 s) of
                Left (_,msg) -> putStrLn msg