From 2f683ef81db95c6da5f4b2c84d176e6d1bee3a00 Mon Sep 17 00:00:00 2001
From: Mark Harrah <dmharrah@gmail.com>
Date: Fri, 8 Nov 2013 20:40:44 -0500
Subject: [PATCH] Generate an error when the incremental compiler is given
 relative source files.  Fixes #923.

Review by @gkossakowski
---
 .../inc/src/main/scala/sbt/inc/Incremental.scala   | 14 ++++++++++++++
 .../relative-source-error/changes/absolute.sbt     |  1 +
 .../relative-source-error/changes/relative.sbt     |  1 +
 .../relative-source-error/src/A.scala              |  1 +
 .../source-dependencies/relative-source-error/test |  4 ++++
 5 files changed, 21 insertions(+)
 create mode 100644 sbt/src/sbt-test/source-dependencies/relative-source-error/changes/absolute.sbt
 create mode 100644 sbt/src/sbt-test/source-dependencies/relative-source-error/changes/relative.sbt
 create mode 100644 sbt/src/sbt-test/source-dependencies/relative-source-error/src/A.scala
 create mode 100644 sbt/src/sbt-test/source-dependencies/relative-source-error/test

diff --git a/compile/inc/src/main/scala/sbt/inc/Incremental.scala b/compile/inc/src/main/scala/sbt/inc/Incremental.scala
index aaa6d3410..8d6442ab2 100644
--- a/compile/inc/src/main/scala/sbt/inc/Incremental.scala
+++ b/compile/inc/src/main/scala/sbt/inc/Incremental.scala
@@ -226,6 +226,7 @@ object Incremental
 		val byProduct = changes.removedProducts.flatMap(previous.produced)
 		val byBinaryDep = changes.binaryDeps.flatMap(previous.usesBinary)
 		val byExtSrcDep = invalidateByExternal(previous, changes.external.modified, log) //changes.external.modified.flatMap(previous.usesExternal) // ++ scopeInvalidations
+		checkAbsolute(srcChanges.added.toList)
 		log.debug(
 			"\nInitial source changes: \n\tremoved:" + srcChanges.removed + "\n\tadded: " + srcChanges.added + "\n\tmodified: " + srcChanges.changed +
 			"\nRemoved products: " + changes.removedProducts +
@@ -240,6 +241,19 @@ object Incremental
 
 		srcDirect ++ byProduct ++ byBinaryDep ++ byExtSrcDep
 	}
+	private[this] def checkAbsolute(addedSources: List[File]): Unit =
+		if(addedSources.nonEmpty) {
+			addedSources.filterNot(_.isAbsolute) match {
+				case first :: more =>
+					val fileStrings = more match {
+						case Nil => first.toString
+						case x :: Nil => s"$first and $x"
+						case _ => s"$first and ${more.size} others"
+					}
+					sys.error(s"The incremental compiler requires absolute sources, but some were relative: $fileStrings")
+				case Nil =>
+			}
+		}
 
 	/** Sources invalidated by `external` sources in other projects according to the previous `relations`. */
 	def invalidateByExternal(relations: Relations, external: Set[String], log: Logger): Set[File] =
diff --git a/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/absolute.sbt b/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/absolute.sbt
new file mode 100644
index 000000000..a5f2d007a
--- /dev/null
+++ b/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/absolute.sbt
@@ -0,0 +1 @@
+scalaSource in Compile := baseDirectory.value / "src"
\ No newline at end of file
diff --git a/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/relative.sbt b/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/relative.sbt
new file mode 100644
index 000000000..8e898fe02
--- /dev/null
+++ b/sbt/src/sbt-test/source-dependencies/relative-source-error/changes/relative.sbt
@@ -0,0 +1 @@
+scalaSource in Compile := file("src")
\ No newline at end of file
diff --git a/sbt/src/sbt-test/source-dependencies/relative-source-error/src/A.scala b/sbt/src/sbt-test/source-dependencies/relative-source-error/src/A.scala
new file mode 100644
index 000000000..528ffce71
--- /dev/null
+++ b/sbt/src/sbt-test/source-dependencies/relative-source-error/src/A.scala
@@ -0,0 +1 @@
+object A
\ No newline at end of file
diff --git a/sbt/src/sbt-test/source-dependencies/relative-source-error/test b/sbt/src/sbt-test/source-dependencies/relative-source-error/test
new file mode 100644
index 000000000..3012aeda3
--- /dev/null
+++ b/sbt/src/sbt-test/source-dependencies/relative-source-error/test
@@ -0,0 +1,4 @@
+$ copy-file changes/relative.sbt build.sbt
+-> compile
+$ copy-file changes/absolute.sbt build.sbt
+> compile