From 2528f7370866f22b6360631602a59367809e8e20 Mon Sep 17 00:00:00 2001
From: Javier Sagredo <jasataco@gmail.com>
Date: Thu, 9 Jan 2025 11:07:17 +0100
Subject: [PATCH] Create noindex.cache if missing

---
 .../src/Distribution/Client/IndexUtils.hs      | 18 +++++++++++++-----
 changelog.d/pr-10730                           | 11 +++++++++++
 2 files changed, 24 insertions(+), 5 deletions(-)
 create mode 100644 changelog.d/pr-10730

diff --git a/cabal-install/src/Distribution/Client/IndexUtils.hs b/cabal-install/src/Distribution/Client/IndexUtils.hs
index 6027f5e53f3..035adde98e0 100644
--- a/cabal-install/src/Distribution/Client/IndexUtils.hs
+++ b/cabal-install/src/Distribution/Client/IndexUtils.hs
@@ -1167,12 +1167,14 @@ readIndexCache verbosity index = do
 -- 'dieWithException's if it fails again). Throws IOException if any arise.
 readNoIndexCache :: Verbosity -> Index -> IO NoIndexCache
 readNoIndexCache verbosity index = do
-  cacheOrFail <- readNoIndexCache' index
+  cacheOrFail <- readNoIndexCache' verbosity index
   case cacheOrFail of
     Left msg -> do
       warn verbosity $
         concat
-          [ "Parsing the index cache failed ("
+          [ "Parsing the index cache for repo \""
+          , unRepoName (repoName repo)
+          , "\" failed ("
           , msg
           , "). "
           , "Trying to regenerate the index cache..."
@@ -1180,10 +1182,12 @@ readNoIndexCache verbosity index = do
 
       updatePackageIndexCacheFile verbosity index
 
-      either (dieWithException verbosity . CorruptedIndexCache) return =<< readNoIndexCache' index
+      either (dieWithException verbosity . CorruptedIndexCache) return =<< readNoIndexCache' verbosity index
 
     -- we don't hash cons local repository cache, they are hopefully small
     Right res -> return res
+  where
+    RepoIndex _ctxt repo = index
 
 -- | Read the 'Index' cache from the filesystem. Throws IO exceptions
 -- if any arise and returns Left on invalid input.
@@ -1194,8 +1198,12 @@ readIndexCache' index
   | otherwise =
       Right . read00IndexCache <$> BSS.readFile (cacheFile index)
 
-readNoIndexCache' :: Index -> IO (Either String NoIndexCache)
-readNoIndexCache' index = structuredDecodeFileOrFail (cacheFile index)
+readNoIndexCache' :: Verbosity -> Index -> IO (Either String NoIndexCache)
+readNoIndexCache' verbosity index = do
+  exists <- doesFileExist (cacheFile index)
+  if exists
+    then structuredDecodeFileOrFail (cacheFile index)
+    else updatePackageIndexCacheFile verbosity index >> readNoIndexCache' verbosity index
 
 -- | Write the 'Index' cache to the filesystem
 writeIndexCache :: Index -> Cache -> IO ()
diff --git a/changelog.d/pr-10730 b/changelog.d/pr-10730
new file mode 100644
index 00000000000..e313e8f2283
--- /dev/null
+++ b/changelog.d/pr-10730
@@ -0,0 +1,11 @@
+synopsis: Create `noindex.cache` file if missing
+packages: cabal-install
+prs: #10730
+issues: #9891
+significance:
+
+description: {
+
+- Local+noindex repositories will have their `noindex.cache` file created the first time they are accessed.
+
+}