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

1 files changed, 36 insertions, 0 deletions

diff --git a/Help/variable/CMAKE_MSVC_DEBUG_INFORMATION_FORMAT.rst b/Help/variable/CMAKE_MSVC_DEBUG_INFORMATION_FORMAT.rst
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+CMAKE_MSVC_DEBUG_INFORMATION_FORMAT
+-----------------------------------
+
+.. versionadded:: 3.25
+
+Select the MSVC debug information format targeting the MSVC ABI.
+This variable is used to initialize the
+:prop_tgt:`MSVC_DEBUG_INFORMATION_FORMAT` property on all targets as they are
+created.  It is also propagated by calls to the :command:`try_compile` command
+into the test project.
+
+The allowed values are:
+
+.. include:: ../prop_tgt/MSVC_DEBUG_INFORMATION_FORMAT-VALUES.txt
+
+Use :manual:`generator expressions <cmake-generator-expressions(7)>` to
+support per-configuration specification.  For example, the code:
+
+.. code-block:: cmake
+
+  set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT "$<$<CONFIG:Debug,RelWithDebInfo>:ProgramDatabase>")
+
+selects for all following targets the program database debug information format
+for the Debug configuration.
+
+If this variable is not set, the :prop_tgt:`MSVC_DEBUG_INFORMATION_FORMAT`
+target property will not be set automatically.  If that property is not set,
+CMake selects a debug information format using the default value
+``$<$<CONFIG:Debug,RelWithDebInfo>:ProgramDatabase>``, if supported by the
+compiler, and otherwise ``$<$<CONFIG:Debug,RelWithDebInfo>:Embedded>``.
+
+.. note::
+
+  This variable has effect only when policy :policy:`CMP0141` is set to ``NEW``
+  prior to the first :command:`project` or :command:`enable_language` command
+  that enables a language using a compiler targeting the MSVC ABI.