refactor: prefer trace over cache

Author: tydeu

src/lake/Lake/Build/Common.lean

@@ -560,17 +560,17 @@ Retrieve artifacts from the Lake cache using only the outputs stored in the save
 open ResolveOutputs in
 /--
 Retrieve artifacts from the Lake cache using the outputs stored in either
-the saved trace file or (unless `traceOnly` is `true`) in the cached input-to-content mapping.
+the saved trace file or in the cached input-to-content mapping.
 
 **For internal use only.**
 -/
 @[inline] public nonrec def getArtifacts?
   [ResolveOutputs α] (inputHash : Hash) (savedTrace : SavedTrace) (pkg : Package)
 : JobM (Option α) := do
-  if let some a ← getArtifactsUsingCache? inputHash pkg then
-    return some a
   if let some a ← getArtifactsUsingTrace? inputHash savedTrace pkg then
     return some a
+  if let some a ← getArtifactsUsingCache? inputHash pkg then
+    return some a
   return none
 
 /-- **For internal use only.** -/

tests/lake/tests/cache/test.sh

@@ -280,9 +280,11 @@ if command -v jq > /dev/null; then # skip if no jq found
   test_cmd rm -f $libPath
   inputHash=$(jq -r '.depHash' $libPath.trace)
   echo $inputHash
+  test_cmd rm -f $libPath.trace
   echo bogus > "$CACHE_DIR/outputs/test/$inputHash.json"
   test_out 'invalid JSON' build Test:static
-  test_cmd rm -f $libPath
+  test_exp -f $libPath
+  test_cmd rm -f $libPath $libPath.trace
   echo '"bogus"' > "$CACHE_DIR/outputs/test/$inputHash.json"
   test_out 'some output(s) have issues' build Test:static
   test_exp -f $libPath

tests/lake/tests/ltar/test.sh

@@ -7,7 +7,7 @@ source ../common.sh
 export LAKE_CACHE_DIR=
 
 #-------------------------------------------------------------------------------
-# The tests covers the (offline) use of `leantar` in Lake
+# This test suite covers the (offline) use of `leantar` in Lake
 #-------------------------------------------------------------------------------
 
 # Test regular build does not produce an `ltar`
@@ -58,13 +58,21 @@ test_exp -f .lake/build/ir/Test.ltar
 # `--keep-local`. Since the build mapping includes module outputs and the
 # tracked mapping only includes the `ltar`, the tracking mapping should
 # require an unpack, whereas the build mapping should not.
+rm -rf .lake/build
 test_run cache add .lake/outputs.jsonl --keep-local
 LAKE_ARTIFACT_CACHE=true test_not_out "leantar" build +Test --no-build -v
+rm -rf .lake/build
 test_run cache add .lake/outputs.jsonl
 LAKE_ARTIFACT_CACHE=true test_out "leantar" build +Test --no-build -v
+rm -rf .lake/build
 # Unpack should have overwritten the cached input with the module outputs
 LAKE_ARTIFACT_CACHE=true test_not_out "leantar" build +Test --no-build -v
 
+# Test that Lake prefers the local trace outputs over the cache
+rm -rf .lake/build.lib/*.[!t]*
+test_run cache add .lake/outputs.jsonl
+LAKE_ARTIFACT_CACHE=true test_not_out "leantar" build +Test --no-build -v
+
 # Test producing an `ltar` without already restored artifacts
 rm -rf .lake/cache .lake/build
 LAKE_ARTIFACT_CACHE=true test_run build +Test -v