From b030a6af88a02b0237a00e6f3df4a5807f338823 Mon Sep 17 00:00:00 2001
From: Craig Scott <craig.scott@crascit.com>
Date: Sat, 3 Oct 2020 18:46:08 +1000
Subject: FetchContent: Raise error if manually given source dir does not exist

Fixes: #21208
---
 Modules/FetchContent.cmake                                        | 6 ++++++
 Tests/RunCMake/FetchContent/ManualSourceDirectory.cmake           | 8 ++++++++
 .../RunCMake/FetchContent/ManualSourceDirectoryMissing-result.txt | 1 +
 .../RunCMake/FetchContent/ManualSourceDirectoryMissing-stderr.txt | 2 ++
 Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing.cmake    | 8 ++++++++
 Tests/RunCMake/FetchContent/RunCMakeTest.cmake                    | 7 +++++++
 6 files changed, 32 insertions(+)
 create mode 100644 Tests/RunCMake/FetchContent/ManualSourceDirectory.cmake
 create mode 100644 Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-result.txt
 create mode 100644 Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-stderr.txt
 create mode 100644 Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing.cmake

diff --git a/Modules/FetchContent.cmake b/Modules/FetchContent.cmake
index acf2a94..40cc362 100644
--- a/Modules/FetchContent.cmake
+++ b/Modules/FetchContent.cmake
@@ -1052,6 +1052,12 @@ function(FetchContent_Populate contentName)
     # The source directory has been explicitly provided in the cache,
     # so no population is required. The build directory may still be specified
     # by the declared details though.
+
+    if(NOT EXISTS "${FETCHCONTENT_SOURCE_DIR_${contentNameUpper}}")
+      message(FATAL_ERROR "Manually specified source directory is missing:\n"
+        "  FETCHCONTENT_SOURCE_DIR_${contentNameUpper} --> ${FETCHCONTENT_SOURCE_DIR_${contentNameUpper}}")
+    endif()
+
     set(${contentNameLower}_SOURCE_DIR "${FETCHCONTENT_SOURCE_DIR_${contentNameUpper}}")
 
     cmake_parse_arguments(savedDetails "" "BINARY_DIR" "" ${contentDetails})
diff --git a/Tests/RunCMake/FetchContent/ManualSourceDirectory.cmake b/Tests/RunCMake/FetchContent/ManualSourceDirectory.cmake
new file mode 100644
index 0000000..83fcc4b
--- /dev/null
+++ b/Tests/RunCMake/FetchContent/ManualSourceDirectory.cmake
@@ -0,0 +1,8 @@
+include(FetchContent)
+
+FetchContent_Declare(
+  WithProject
+  SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/ADirThatDoesNotExist
+)
+
+FetchContent_MakeAvailable(WithProject)
diff --git a/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-result.txt b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-stderr.txt b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-stderr.txt
new file mode 100644
index 0000000..7ecb06b
--- /dev/null
+++ b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing-stderr.txt
@@ -0,0 +1,2 @@
+ *Manually specified source directory is missing:
++ *FETCHCONTENT_SOURCE_DIR_WITHPROJECT --> .*/ADirThatDoesNotExist
diff --git a/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing.cmake b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing.cmake
new file mode 100644
index 0000000..0e24c1a
--- /dev/null
+++ b/Tests/RunCMake/FetchContent/ManualSourceDirectoryMissing.cmake
@@ -0,0 +1,8 @@
+include(FetchContent)
+
+FetchContent_Declare(
+  WithProject
+  SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/WithProject
+)
+
+FetchContent_MakeAvailable(WithProject)
diff --git a/Tests/RunCMake/FetchContent/RunCMakeTest.cmake b/Tests/RunCMake/FetchContent/RunCMakeTest.cmake
index ad9e48e..3eb331f 100644
--- a/Tests/RunCMake/FetchContent/RunCMakeTest.cmake
+++ b/Tests/RunCMake/FetchContent/RunCMakeTest.cmake
@@ -15,6 +15,13 @@ run_cmake(MakeAvailable)
 run_cmake(MakeAvailableTwice)
 run_cmake(MakeAvailableUndeclared)
 
+run_cmake_with_options(ManualSourceDirectory
+  -D "FETCHCONTENT_SOURCE_DIR_WITHPROJECT=${CMAKE_CURRENT_LIST_DIR}/WithProject"
+)
+run_cmake_with_options(ManualSourceDirectoryMissing
+  -D "FETCHCONTENT_SOURCE_DIR_WITHPROJECT=${CMAKE_CURRENT_LIST_DIR}/ADirThatDoesNotExist"
+)
+
 function(run_FetchContent_DirOverrides)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/DirOverrides-build)
   file(REMOVE_RECURSE "${RunCMake_TEST_BINARY_DIR}")
-- 
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