genex: Add TARGET_NAME_IF_EXISTS expression

Define `$<TARGET_NAME_IF_EXISTS:tgt>` to mean `tgt` if the target
exists and otherwise an empty string.

11 files changed, 43 insertions, 0 deletions

diff --git a/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake b/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
index f9a5cae..5636d00 100644
--- a/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
+++ b/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
@@ -38,6 +38,10 @@ run_cmake(TARGET_EXISTS-no-arg)
 run_cmake(TARGET_EXISTS-empty-arg)
 run_cmake(TARGET_EXISTS)
 run_cmake(TARGET_EXISTS-not-a-target)
+run_cmake(TARGET_NAME_IF_EXISTS-no-arg)
+run_cmake(TARGET_NAME_IF_EXISTS-empty-arg)
+run_cmake(TARGET_NAME_IF_EXISTS)
+run_cmake(TARGET_NAME_IF_EXISTS-not-a-target)
 
 run_cmake(ImportedTarget-TARGET_BUNDLE_DIR)
 run_cmake(ImportedTarget-TARGET_BUNDLE_CONTENT_DIR)
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-check.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-check.cmake
new file mode 100644
index 0000000..2f57430
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-check.cmake
@@ -0,0 +1,6 @@
+file(READ "${RunCMake_TEST_BINARY_DIR}/TARGET_NAME_IF_EXISTS-generated.txt" content)
+
+set(expected "foo")
+if(NOT content STREQUAL expected)
+  set(RunCMake_TEST_FAILED "actual content:\n [[${content}]]\nbut expected:\n [[${expected}]]")
+endif()
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-result.txt b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-stderr.txt b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-stderr.txt
new file mode 100644
index 0000000..5ee13b7
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg-stderr.txt
@@ -0,0 +1,9 @@
+CMake Error at TARGET_NAME_IF_EXISTS-empty-arg.cmake:2 \(file\):
+  Error evaluating generator expression:
+
+    \$<TARGET_NAME_IF_EXISTS:>
+
+  \$<TARGET_NAME_IF_EXISTS:tgt> expression requires a non-empty valid target
+  name.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg.cmake
new file mode 100644
index 0000000..f5034f4
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-empty-arg.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0070 NEW)
+file(GENERATE OUTPUT TARGET_NAME_IF_EXISTS-generated.txt CONTENT "$<TARGET_NAME_IF_EXISTS:${empty}>")
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-result.txt b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-stderr.txt b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-stderr.txt
new file mode 100644
index 0000000..4122425
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg-stderr.txt
@@ -0,0 +1,8 @@
+CMake Error at TARGET_NAME_IF_EXISTS-no-arg.cmake:2 \(file\):
+  Error evaluating generator expression:
+
+    \$<TARGET_NAME_IF_EXISTS>
+
+  \$<TARGET_NAME_IF_EXISTS> expression requires exactly one parameter.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg.cmake
new file mode 100644
index 0000000..3293094
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-no-arg.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0070 NEW)
+file(GENERATE OUTPUT TARGET_NAME_IF_EXISTS-generated.txt CONTENT "$<TARGET_NAME_IF_EXISTS>")
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target-check.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target-check.cmake
new file mode 100644
index 0000000..2085c16
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target-check.cmake
@@ -0,0 +1,5 @@
+file(READ "${RunCMake_TEST_BINARY_DIR}/TARGET_NAME_IF_EXISTS-not-a-target-generated.txt" content)
+
+if(content)
+  set(RunCMake_TEST_FAILED "actual content:\n [[${content}]]\nbut expected an empty string")
+endif()
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target.cmake
new file mode 100644
index 0000000..a054e6c
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS-not-a-target.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0070 NEW)
+file(GENERATE OUTPUT TARGET_NAME_IF_EXISTS-not-a-target-generated.txt CONTENT "$<TARGET_NAME_IF_EXISTS:just-random-string>")
diff --git a/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS.cmake b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS.cmake
new file mode 100644
index 0000000..0ce3b1d
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/TARGET_NAME_IF_EXISTS.cmake
@@ -0,0 +1,3 @@
+cmake_policy(SET CMP0070 NEW)
+add_custom_target(foo)
+file(GENERATE OUTPUT TARGET_NAME_IF_EXISTS-generated.txt CONTENT "$<TARGET_NAME_IF_EXISTS:foo>")