try_compile: Restore expansion of ;-list in COMPILE_DEFINITIONS

The quoting added by commit 8c5221fb1f (try_compile: Preserve special
characters in COMPILE_DEFINITIONS, 2019-01-21, v3.14.0-rc1~108^2~3)
broke the case that the `COMPILE_DEFINITIONS` value contains a `;`.
Without the quoting the `;` would be generated literally in an unquoted
argument in the test `CMakeLists.txt` file and would then be expanded.
With quoting the `;` is preserved, which is not the old behavior.

Fix this by expanding the `;`-list ahead of time.  Add test cases for
behavior with both `#` and `;`.

This was noticed with the PGI compiler where we set
`CMAKE_CXX*_STANDARD_COMPILE_OPTION` to values like `--c++17;-A`.  The
symptom had also been observed while preparing commit ef8f237686
(ParseImplicitIncludeInfo: add SunPro Fortran and PGI compiler, Cray
fix, 2019-01-29, v3.14.0-rc1~26^2~2) but was not recognized at the time
as a regression.  Revert the workaround added by that commit.

Fixes: #18919

2 files changed, 39 insertions, 0 deletions

diff --git a/Tests/TryCompile/CMakeLists.txt b/Tests/TryCompile/CMakeLists.txt
index 184a7be5c8..54e96a2086 100644
--- a/Tests/TryCompile/CMakeLists.txt
+++ b/Tests/TryCompile/CMakeLists.txt
@@ -165,6 +165,35 @@ try_compile(TEST_INNER
   OUTPUT_VARIABLE output)
 TEST_ASSERT(TEST_INNER "try_compile project mode failed:\n${output}")
 
+try_compile(COMPILE_DEFINITIONS_LIST_EXPANDED
+    ${TryCompile_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp
+    ${TryCompile_SOURCE_DIR}/check_a_b.c
+    OUTPUT_VARIABLE output
+    COMPILE_DEFINITIONS "-DDEF_A;-DDEF_B"
+    )
+if(COMPILE_DEFINITIONS_LIST_EXPANDED)
+  message(STATUS "COMPILE_DEFINITIONS list expanded correctly")
+else()
+  string(REPLACE "\n" "\n  " output "  ${output}")
+  message(SEND_ERROR "COMPILE_DEFINITIONS list did not expand correctly\n${output}")
+endif()
+
+try_compile(SHOULD_FAIL_DUE_TO_BAD_SOURCE
+    ${TryCompile_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp
+    ${TryCompile_SOURCE_DIR}/pass.c
+    OUTPUT_VARIABLE output
+    COMPILE_DEFINITIONS "bad#source.c"
+    )
+if(SHOULD_FAIL_DUE_TO_BAD_SOURCE AND NOT CMAKE_GENERATOR MATCHES "Watcom WMake|NMake Makefiles")
+  string(REPLACE "\n" "\n  " output "  ${output}")
+  message(SEND_ERROR "try_compile with bad#source.c did not fail:\n${output}")
+elseif(NOT output MATCHES [[(bad#source\.c|bad\\)]])
+  string(REPLACE "\n" "\n  " output "  ${output}")
+  message(SEND_ERROR "try_compile with bad#source.c failed without mentioning bad source:\n${output}")
+else()
+  message(STATUS "try_compile with bad#source.c correctly failed")
+endif()
+
 add_executable(TryCompile pass.c)
 
 ######################################
diff --git a/Tests/TryCompile/check_a_b.c b/Tests/TryCompile/check_a_b.c
new file mode 100644
index 0000000000..05fba0f828
--- /dev/null
+++ b/Tests/TryCompile/check_a_b.c
@@ -0,0 +1,10 @@
+#ifndef DEF_A
+#  error DEF_A not defined
+#endif
+#ifndef DEF_B
+#  error DEF_B not defined
+#endif
+int main()
+{
+  return 0;
+}