Add a CPP flag for each available DAML-LF feature. (digital-asset#2896)

* Expose Daml LF features as a CPP flags. * Add missing text dependency
TuranDev · Sep 16, 2019 · dc32abb · dc32abb
1 parent 249e8a6
commit dc32abb
Show file tree

Hide file tree

Showing 4 changed files with 18 additions and 2 deletions.
diff --git a/compiler/daml-lf-ast/src/DA/Daml/LF/Ast/Version.hs b/compiler/daml-lf-ast/src/DA/Daml/LF/Ast/Version.hs
@@ -49,6 +49,8 @@ supportedInputVersions = version1_5 : supportedOutputVersions
 data Feature = Feature
     { featureName :: !T.Text
     , featureMinVersion :: !Version
+    , featureCppFlag :: !T.Text
+        -- ^ CPP flag to test for availability of the feature.
     }
 
 -- NOTE(MH): We comment this out to leave an example how to deal with features.
@@ -59,8 +61,17 @@ featureNumeric :: Feature
 featureNumeric = Feature
     { featureName = "Numeric type"
     , featureMinVersion = version1_7
+    , featureCppFlag = "DAML_NUMERIC"
     }
 
+allFeatures :: [Feature]
+allFeatures =
+    [ featureNumeric
+    ]
+
+allFeaturesForVersion :: Version -> [Feature]
+allFeaturesForVersion version = filter (supports version) allFeatures
+
 supports :: Version -> Feature -> Bool
 supports version feature = version >= featureMinVersion feature
 

diff --git a/compiler/damlc/daml-lf-conversion/src/DA/Daml/LFConversion/Primitives.hs b/compiler/damlc/daml-lf-conversion/src/DA/Daml/LFConversion/Primitives.hs
@@ -199,7 +199,7 @@ _whenRuntimeSupports version feature t e
     | otherwise = runtimeUnsupported feature t
 
 runtimeUnsupported :: Feature -> Type -> Expr
-runtimeUnsupported (Feature name version) t =
+runtimeUnsupported (Feature name version _) t =
   ETmApp
   (ETyApp (EBuiltin BEError) t)
   (EBuiltin (BEText (name <> " only supported when compiling to DAML-LF " <> T.pack (renderVersion version) <> " or later")))
diff --git a/compiler/damlc/daml-opts/BUILD.bazel b/compiler/damlc/daml-opts/BUILD.bazel
@@ -43,6 +43,7 @@ da_haskell_library(
         "ghc-lib-parser",
         "ghcide",
         "mtl",
+        "text",
     ],
     src_strip_prefix = "daml-opts",
     visibility = ["//visibility:public"],

diff --git a/compiler/damlc/daml-opts/daml-opts/DA/Daml/Options.hs b/compiler/damlc/daml-opts/daml-opts/DA/Daml/Options.hs
@@ -19,6 +19,7 @@ import Data.Bifunctor
 import Data.IORef
 import Data.List
 import DynFlags (parseDynamicFilePragma)
+import qualified Data.Text as T
 import qualified Platform as P
 import qualified EnumSet
 import GHC                         hiding (convertLit)
@@ -29,6 +30,7 @@ import HscMain
 import Panic (throwGhcExceptionIO)
 import System.Directory
 import System.FilePath
+import qualified DA.Daml.LF.Ast.Version as LF
 
 import DA.Daml.Options.Types
 import DA.Daml.Preprocessor
@@ -244,7 +246,7 @@ adjustDynFlags options@Options{..} tmpDir dflags
         Nothing -> id
         Just cppPath -> alterSettings $ \s -> s
             { sPgm_P = (cppPath, [])
-            , sOpt_P = ["-P"]
+            , sOpt_P = "-P" : ["-D" <> T.unpack flag | flag <- cppFlags]
                 -- We add "-P" here to suppress #line pragmas from the
                 -- preprocessor (hpp, specifically) because the daml
                 -- parser can't handle them. This is a non-issue right now
@@ -257,6 +259,8 @@ adjustDynFlags options@Options{..} tmpDir dflags
                 -- sometimes this is required by CPP?
             }
 
+    cppFlags = map LF.featureCppFlag (LF.allFeaturesForVersion optDamlLfVersion)
+
     -- We need to add platform info in order to run CPP. To prevent
     -- .hi file incompatibilities, we set the platform the same way
     -- for everyone even if they don't use CPP.