Make copyBootJarsToPredefinedLocations simpler and less fragile

Previously, copyBootJarsToPredefinedLocations relied on all its
parameters having the same length and the same order. That made it
quite fragile as changes to one of the parameters without corresponding
changes to the other would cause failures. It also combined the
retrieval of the boot dex jars from the modules, handling of missing
boot dex jar files and the generation of the rules to copy the files.

This change separates the retrieval of boot dex jars and handling of
missing files from the copying of those files while at the same time
making the function less fragile by replacing the three ordered
parameters with two maps that shared common keys.

Bug: 179354495
Test: m nothing
Change-Id: Idbcd24a7e8af89f7895a20aeddc58502dcbaad03

java/dexpreopt_bootjars.go

@@ -15,7 +15,6 @@
 package java
 
 import (
-	"fmt"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -254,6 +253,9 @@ type bootImageConfig struct {
 	dexPaths     android.WritablePaths // for this image
 	dexPathsDeps android.WritablePaths // for the dependency images and in this image
 
+	// Map from module name (without prebuilt_ prefix) to the predefined build path.
+	dexPathsByModule map[string]android.WritablePath
+
 	// File path to a zip archive with all image files (or nil, if not needed).
 	zip android.WritablePath
 
@@ -461,53 +463,27 @@ func shouldBuildBootImages(config android.Config, global *dexpreopt.GlobalConfig
 	return true
 }
 
-// copyBootJarsToPredefinedLocations generates commands that will copy boot jars to
-// predefined paths in the global config.
-func copyBootJarsToPredefinedLocations(ctx android.ModuleContext, bootModules []android.Module, bootjars android.ConfiguredJarList, jarPathsPredefined android.WritablePaths) {
-	jarPaths := make(android.Paths, bootjars.Len())
-	for i, module := range bootModules {
-		if module != nil {
-			bootDexJar := module.(interface{ DexJarBuildPath() android.Path }).DexJarBuildPath()
-			jarPaths[i] = bootDexJar
-
-			name := android.RemoveOptionalPrebuiltPrefix(ctx.OtherModuleName(module))
-			if bootjars.Jar(i) != name {
-				ctx.ModuleErrorf("expected module %s at position %d but found %s", bootjars.Jar(i), i, name)
-			}
-		}
-	}
-
-	// The paths to bootclasspath DEX files need to be known at module GenerateAndroidBuildAction
-	// time, before the boot images are built (these paths are used in dexpreopt rule generation for
-	// Java libraries and apps). Generate rules that copy bootclasspath DEX jars to the predefined
-	// paths.
-	for i := range jarPaths {
-		input := jarPaths[i]
-		output := jarPathsPredefined[i]
-		module := bootjars.Jar(i)
-		if input == nil {
-			if ctx.Config().AllowMissingDependencies() {
-				apex := bootjars.Apex(i)
-
-				// Create an error rule that pretends to create the output file but will actually fail if it
-				// is run.
-				ctx.Build(pctx, android.BuildParams{
-					Rule:   android.ErrorRule,
-					Output: output,
-					Args: map[string]string{
-						"error": fmt.Sprintf("missing dependencies: dex jar for %s:%s", module, apex),
-					},
-				})
-			} else {
-				ctx.ModuleErrorf("failed to find a dex jar path for module '%s'"+
-					", note that some jars may be filtered out by module constraints", module)
-			}
+// copyBootJarsToPredefinedLocations generates commands that will copy boot jars to predefined
+// paths in the global config.
+func copyBootJarsToPredefinedLocations(ctx android.ModuleContext, srcBootDexJarsByModule bootDexJarByModule, dstBootJarsByModule map[string]android.WritablePath) {
+	// Create the super set of module names.
+	names := []string{}
+	names = append(names, android.SortedStringKeys(srcBootDexJarsByModule)...)
+	names = append(names, android.SortedStringKeys(dstBootJarsByModule)...)
+	names = android.SortedUniqueStrings(names)
+	for _, name := range names {
+		src := srcBootDexJarsByModule[name]
+		dst := dstBootJarsByModule[name]
 
+		if src == nil {
+			ctx.ModuleErrorf("module %s does not provide a dex boot jar", name)
+		} else if dst == nil {
+			ctx.ModuleErrorf("module %s is not part of the boot configuration", name)
 		} else {
 			ctx.Build(pctx, android.BuildParams{
 				Rule:   android.Cp,
-				Input:  input,
-				Output: output,
+				Input:  src,
+				Output: dst,
 			})
 		}
 	}