From c4a4a3819388fb22dff876df9022aa82ce735fa4 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@digitalasset.com>
Date: Tue, 12 Nov 2024 15:28:50 +0000
Subject: [PATCH] Fix module-prefix changes being ignored (#20288)

* Add module prefixes to package-db reinitialisation check

* Extend module-prefixes test to include this behaviour
---
 sdk/compiler/damlc/lib/DA/Cli/Damlc/Packaging.hs  | 12 ++++++++----
 sdk/compiler/damlc/tests/src/DA/Test/Packaging.hs | 15 +++++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/sdk/compiler/damlc/lib/DA/Cli/Damlc/Packaging.hs b/sdk/compiler/damlc/lib/DA/Cli/Damlc/Packaging.hs
index 0674c80cfcbf..ea68d724d0ab 100644
--- a/sdk/compiler/damlc/lib/DA/Cli/Damlc/Packaging.hs
+++ b/sdk/compiler/damlc/lib/DA/Cli/Damlc/Packaging.hs
@@ -83,7 +83,7 @@ import SdkVersion.Class (SdkVersioned, damlStdlib)
 createProjectPackageDb :: SdkVersioned => NormalizedFilePath -> Options -> MS.Map UnitId GHC.ModuleName -> IO ()
 createProjectPackageDb projectRoot (disableScenarioService -> opts) modulePrefixes
   = do
-    (needsReinitalization, depsFingerprint) <- dbNeedsReinitialization projectRoot depsDir
+    (needsReinitalization, depsFingerprint) <- dbNeedsReinitialization projectRoot depsDir modulePrefixes
     loggerH <- getLogger opts "package-db"
     when needsReinitalization $ do
       Logger.logDebug loggerH "package db is not up2date, reinitializing"
@@ -221,8 +221,8 @@ createProjectPackageDb projectRoot (disableScenarioService -> opts) modulePrefix
 -- | Compute the hash over all dependencies and compare it to the one stored in the metadata file in
 -- the package db to decide whether to run reinitialization or not.
 dbNeedsReinitialization ::
-       NormalizedFilePath -> FilePath -> IO (Bool, Fingerprint)
-dbNeedsReinitialization projectRoot depsDir = do
+       NormalizedFilePath -> FilePath -> MS.Map UnitId GHC.ModuleName -> IO (Bool, Fingerprint)
+dbNeedsReinitialization projectRoot depsDir modulePrefixes = do
     allDeps <- listFilesRecursive depsDir
     fileFingerprints <- mapM getFileHash allDeps
     let depsFingerprint = fingerprintFingerprints fileFingerprints
@@ -231,7 +231,11 @@ dbNeedsReinitialization projectRoot depsDir = do
     pure $
         case errOrmetaData of
             Left _err -> (True, depsFingerprint)
-            Right metaData -> (fingerprintDependencies metaData /= depsFingerprint, depsFingerprint)
+            Right metaData ->
+              let fingerprintChanged = fingerprintDependencies metaData /= depsFingerprint
+                  -- Use `fst` to throw away the contained module list, as the daml.yaml doesn't contain this information
+                  modulePrefixesChanged = (fst <$> moduleRenamings metaData) /= modulePrefixes
+               in (fingerprintChanged || modulePrefixesChanged, depsFingerprint)
 
 disableScenarioService :: Options -> Options
 disableScenarioService opts = opts
diff --git a/sdk/compiler/damlc/tests/src/DA/Test/Packaging.hs b/sdk/compiler/damlc/tests/src/DA/Test/Packaging.hs
index 168e79837f61..706379d921a4 100644
--- a/sdk/compiler/damlc/tests/src/DA/Test/Packaging.hs
+++ b/sdk/compiler/damlc/tests/src/DA/Test/Packaging.hs
@@ -1073,6 +1073,21 @@ tests Tools{damlc} = testGroup "Packaging" $
             , "main = dep1 + dep2"
             ]
           callProcessSilent damlc ["build", "--project-root", dir </> "main", "-o", "main.dar"]
+          step "Changing module prefixes"
+          writeFileUTF8 (dir </> "main" </> "daml.yaml") $ unlines
+            [ "sdk-version: " <> sdkVersion
+            , "name: main"
+            , "version: 0.0.1"
+            , "source: ."
+            , "dependencies: [daml-prim, daml-stdlib]"
+            , "data-dependencies:"
+            , "  - " <> show (dir </> "dep1" </> "dep1.dar")
+            , "  - " <> show (dir </> "dep2" </> "dep2.dar")
+            , "module-prefixes:"
+            , "  dep-1.0.0: Dep3"
+            , "  dep-2.0.0: Dep4"
+            ]
+          buildProjectError (dir </> "main") "" "Could not find module"
     , testCaseSteps "relative output filepath" $ \step -> withTempDir $ \dir -> do
           step "Create project"
           writeFileUTF8 (dir </> "daml.yaml") $ unlines