MSVC: Add abstraction for debug information format

Replace our hard-coded default for `/Zi` with a first-class abstraction
to select the debug information format an enumeration of logical
names.  We've long hesitated to do this because the idea of "debug
information format" touches on related concepts on several platforms.
Avoid that scope creep by simply defining an abstraction that applies
only when targeting the MSVC ABI on Windows.

Removing the old default flag requires a policy because existing
projects may rely on string processing to edit them and choose a
runtime library under the old behavior.  Add policy CMP0141 to
provide compatibility.

Fixes: #10189

10 files changed, 56 insertions, 0 deletions

diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-result.txt b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-stderr.txt b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-stderr.txt
new file mode 100644
index 0000000..fb61d4b
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW-stderr.txt
@@ -0,0 +1,5 @@
+^CMake Error in CMakeLists.txt:
+  MSVC_DEBUG_INFORMATION_FORMAT value 'BogusValue' not known for this (C|CXX)
+  compiler.
++
+CMake Generate step failed\.  Build files cannot be regenerated correctly\.$
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW.cmake
new file mode 100644
index 0000000..165ea38
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NEW.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0141 NEW)
+include(CMP0141-common.cmake)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NoEffect.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NoEffect.cmake
new file mode 100644
index 0000000..82754a9
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-NoEffect.cmake
@@ -0,0 +1,4 @@
+include(CMP0141-common.cmake)
+
+# Setting this policy after enable_language command has no effect.
+cmake_policy(SET CMP0141 NEW)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-OLD.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-OLD.cmake
new file mode 100644
index 0000000..7bbe586
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-OLD.cmake
@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0141 OLD)
+include(CMP0141-common.cmake)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-WARN.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-WARN.cmake
new file mode 100644
index 0000000..912112a
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-WARN.cmake
@@ -0,0 +1,2 @@
+
+include(CMP0141-common.cmake)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-common.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-common.cmake
new file mode 100644
index 0000000..8e43a25
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMP0141-common.cmake
@@ -0,0 +1,31 @@
+enable_language(CXX)
+
+cmake_policy(GET CMP0141 cmp0141)
+if(cmp0141 STREQUAL "NEW")
+  if(NOT CMAKE_MSVC_DEBUG_INFORMATION_FORMAT_DEFAULT)
+    message(SEND_ERROR "CMAKE_MSVC_DEBUG_INFORMATION_FORMAT_DEFAULT not set under NEW behavior")
+  endif()
+else()
+  if(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT_DEFAULT)
+    message(SEND_ERROR "CMAKE_MSVC_DEBUG_INFORMATION_FORMAT_DEFAULT is set under OLD behavior")
+  endif()
+endif()
+
+if(cmp0141 STREQUAL "NEW")
+  if(CMAKE_CXX_FLAGS_DEBUG MATCHES "[/-]Zi( |$)")
+    message(SEND_ERROR "CMAKE_CXX_FLAGS_DEBUG has -Zi flags under NEW behavior.")
+  endif()
+  if(CMAKE_CXX_FLAGS_RELWITHDEBINFO MATCHES "[/-]Zi( |$)")
+    message(SEND_ERROR "CMAKE_CXX_FLAGS_RELWITHDEBINFO has -Zi flags under NEW behavior.")
+  endif()
+else()
+  if(NOT (CMAKE_CXX_FLAGS_DEBUG MATCHES "[/-]Zi( |$)"))
+    message(SEND_ERROR "CMAKE_CXX_FLAGS_DEBUG does not have -Zi flags under OLD behavior.")
+  endif()
+  if(NOT (CMAKE_CXX_FLAGS_RELWITHDEBINFO MATCHES "[/-]Zi( |$)"))
+    message(SEND_ERROR "CMAKE_CXX_FLAGS_RELWITHDEBINFO does not have -Zi flags under OLD behavior.")
+  endif()
+endif()
+
+set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT BogusValue)
+add_library(foo empty.cxx)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/CMakeLists.txt b/Tests/RunCMake/MSVCDebugInformationFormat/CMakeLists.txt
new file mode 100644
index 0000000..aba1016
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.24)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/RunCMakeTest.cmake b/Tests/RunCMake/MSVCDebugInformationFormat/RunCMakeTest.cmake
new file mode 100644
index 0000000..f678acf
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/RunCMakeTest.cmake
@@ -0,0 +1,6 @@
+include(RunCMake)
+
+run_cmake(CMP0141-WARN)
+run_cmake(CMP0141-OLD)
+run_cmake(CMP0141-NEW)
+run_cmake(CMP0141-NoEffect)
diff --git a/Tests/RunCMake/MSVCDebugInformationFormat/empty.cxx b/Tests/RunCMake/MSVCDebugInformationFormat/empty.cxx
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/Tests/RunCMake/MSVCDebugInformationFormat/empty.cxx