Fix Windows CPP issues (#2991)

The issue was actually not really related to CPP but to the lack of
sandboxing on Windows. That resulted in us overwriting Prelude.hi from
the 1.dev rule with the Prelude.hi from the 1.6 rule in some cases
which caused the error we were seeing.

fixes #2983

compiler/damlc/daml-stdlib-src/Prelude.daml

@@ -16,7 +16,7 @@ import DA.Internal.LF as X hiding (Pair(..), TextMap, unpackPair)
 -- Windows so for now we always expose this
 -- and crash at runtime if you use fromAnyTemplate/toAnyTemplate
 -- with older LF versions.
-#if 1
+#ifdef DAML_ANY_TEMPLATE
 import DA.Internal.Template as X
 #else
 import DA.Internal.Template as X hiding (fromAnyTemplate, toAnyTemplate)

compiler/damlc/lib/DA/Cli/Damlc.hs

@@ -146,6 +146,7 @@ cmdCompile numProcessors =
         <$> inputFileOpt
         <*> outputFileOpt
         <*> optionsParser numProcessors (EnableScenarioService False) optPackageName
+        <*> optional (strOption $ long "iface-dir" <> metavar "IFACE_DIR" <> help "Directory for interface files")
 
 cmdLint :: Int -> Mod CommandFields Command
 cmdLint numProcessors =
@@ -367,14 +368,14 @@ execIde telemetry (Debug debug) enableScenarioService ghcOpts mbProfileDir = Com
                       getDamlIdeState opts mbScenarioService loggerH sendMsg vfs (clientSupportsProgress caps)
 
 
-execCompile :: FilePath -> FilePath -> Options -> Command
-execCompile inputFile outputFile opts =
+execCompile :: FilePath -> FilePath -> Options -> Maybe FilePath -> Command
+execCompile inputFile outputFile opts mbIfaceDir =
   Command Compile effect
   where
     effect = withProjectRoot' (ProjectOpts Nothing (ProjectCheck "" False)) $ \relativize -> do
       loggerH <- getLogger opts "compile"
       inputFile <- toNormalizedFilePath <$> relativize inputFile
-      opts' <- mkOptions opts
+      opts' <- mkOptions opts { optIfaceDir = mbIfaceDir }
       withDamlIdeState opts' loggerH diagnosticsLogger $ \ide -> do
           setFilesOfInterest ide (Set.singleton inputFile)
           runAction ide $ do

compiler/damlc/pkg-db/util.bzl

@@ -105,21 +105,27 @@ def _daml_package_rule_impl(ctx):
         tools = [ctx.executable.damlc_bootstrap, ctx.executable.cpp],
         progress_message = "Compiling " + name + ".daml to daml-lf " + ctx.attr.daml_lf_version,
         command = """
-      set -eoux pipefail
+      set -eou pipefail
       PKG_NAME=`cat {pkg_name_version_file}`
 
+      # We use a temp directory here to avoid issues due to the lack of sandboxing
+      # on Windows.
+      IFACE_DIR=$(mktemp -d)
+
       # Compile the dalf file
       {damlc_bootstrap} compile \
         --package-name $PKG_NAME \
         --package-db {package_db_dir} \
         --write-iface \
+        --iface-dir $IFACE_DIR \
         --target {daml_lf_version} \
         --cpp {cpp} \
         -o {dalf_file} \
         {main}
 
       cp -a {pkg_root}/* {iface_dir}
-      cp -a .daml/interfaces/{pkg_root}/* {iface_dir}
+      cp -a $IFACE_DIR/{pkg_root}/* {iface_dir}
+      rm -rf $IFACE_DIR
     """.format(
             main = modules[ctx.attr.main],
             pkg_name_version_file = pkg_name_version.path,