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, 35 insertions, 0 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index b44d2a0380..defcba326c 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2041,6 +2041,41 @@ void cmLocalGenerator::AddLanguageFlags(std::string& flags,
       }
     }
   }
+
+  // Add MSVC debug information format flags. This is activated by the presence
+  // of a default selection whether or not it is overridden by a property.
+  cmValue msvcDebugInformationFormatDefault = this->Makefile->GetDefinition(
+    "CMAKE_MSVC_DEBUG_INFORMATION_FORMAT_DEFAULT");
+  if (cmNonempty(msvcDebugInformationFormatDefault)) {
+    cmValue msvcDebugInformationFormatValue =
+      target->GetProperty("MSVC_DEBUG_INFORMATION_FORMAT");
+    if (!msvcDebugInformationFormatValue) {
+      msvcDebugInformationFormatValue = msvcDebugInformationFormatDefault;
+    }
+    std::string const msvcDebugInformationFormat =
+      cmGeneratorExpression::Evaluate(*msvcDebugInformationFormatValue, this,
+                                      config, target);
+    if (!msvcDebugInformationFormat.empty()) {
+      if (cmValue msvcDebugInformationFormatOptions =
+            this->Makefile->GetDefinition(
+              cmStrCat("CMAKE_", lang,
+                       "_COMPILE_OPTIONS_MSVC_DEBUG_INFORMATION_FORMAT_",
+                       msvcDebugInformationFormat))) {
+        this->AppendCompileOptions(flags, *msvcDebugInformationFormatOptions);
+      } else if ((this->Makefile->GetSafeDefinition(
+                    cmStrCat("CMAKE_", lang, "_COMPILER_ID")) == "MSVC"_s ||
+                  this->Makefile->GetSafeDefinition(
+                    cmStrCat("CMAKE_", lang, "_SIMULATE_ID")) == "MSVC"_s) &&
+                 !cmSystemTools::GetErrorOccurredFlag()) {
+        // The compiler uses the MSVC ABI so it needs a known runtime library.
+        this->IssueMessage(MessageType::FATAL_ERROR,
+                           cmStrCat("MSVC_DEBUG_INFORMATION_FORMAT value '",
+                                    msvcDebugInformationFormat,
+                                    "' not known for this ", lang,
+                                    " compiler."));
+      }
+    }
+  }
 }
 
 void cmLocalGenerator::AddLanguageFlagsForLinking(