Fix #2840: Build collision for single-package and FILE_FULL_PATH

source/dub/generators/build.d

@@ -216,7 +216,7 @@ class BuildGenerator : ProjectGenerator {
 		auto cwd = settings.toolWorkingDirectory;
 		bool generate_binary = !(buildsettings.options & BuildOption.syntaxOnly);
 
-		auto build_id = buildsettings.computeBuildID(config, settings);
+		auto build_id = buildsettings.computeBuildID(pack.path, config, settings);
 
 		// make all paths relative to shrink the command line
 		string makeRelative(string path) { return shrinkPath(NativePath(path), cwd); }

source/dub/generators/generator.d

@@ -828,7 +828,8 @@ package(dub) NativePath targetCacheDir(NativePath cachePath, in Package pkg, str
  * library-debug-Z7qINYX4IxM8muBSlyNGrw
  * ```
  */
-package(dub) string computeBuildID(in BuildSettings buildsettings, string config, GeneratorSettings settings)
+package(dub) string computeBuildID(in BuildSettings buildsettings,
+	in NativePath packagePath, string config, GeneratorSettings settings)
 {
 	import std.conv : to;
 
@@ -843,6 +844,8 @@ package(dub) string computeBuildID(in BuildSettings buildsettings, string config
 		settings.platform.architecture,
 		[
 			(cast(uint)(buildsettings.options & ~BuildOption.color)).to!string, // exclude color option from id
+			// Needed for things such as `__FULL_FILE_PATH__`
+			packagePath.toNativeString(),
 			settings.platform.compilerBinary,
 			settings.platform.compiler,
 			settings.platform.compilerVersion,

source/dub/generators/targetdescription.d

@@ -45,7 +45,7 @@ class TargetDescriptionGenerator : ProjectGenerator {
 			d.packages = ti.packages.map!(p => p.name).array;
 			d.rootConfiguration = ti.config;
 			d.buildSettings = ti.buildSettings.dup;
-			const buildId = computeBuildID(d.buildSettings, ti.config, settings);
+			const buildId = computeBuildID(d.buildSettings, ti.pack.path, ti.config, settings);
 			const filename = settings.compiler.getTargetFileName(d.buildSettings, settings.platform);
 			d.cacheArtifactPath = (targetCacheDir(settings.cache, ti.pack, buildId) ~ filename).toNativeString();
 			d.dependencies = ti.dependencies.dup;

test/issue2840-build-collision.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+. $(dirname "${BASH_SOURCE[0]}")/common.sh
+
+pushd $(dirname "${BASH_SOURCE[0]}")/issue2840-build-collision
+# Copy before building, as dub uses timestamp to check for rebuild
+rm -rf nested/ && mkdir -p nested/ && cp -v build.d nested/
+
+$DUB ./build.d $(pwd)/build.d
+pushd nested
+$DUB ./build.d $(pwd)/build.d
+popd
+
+popd

test/issue2840-build-collision/build.d

@@ -0,0 +1,16 @@
+#!/usr/bin/env dub
+/++ dub.json:
+   {
+       "name": "build"
+   }
++/
+
+import std.format;
+
+immutable FullPath = __FILE_FULL_PATH__;
+
+void main (string[] args)
+{
+    assert(args.length == 2, "Expected a single argument");
+    assert(args[1] == FullPath, format("%s != %s -- %s", args[1], FullPath, args[0]));
+}