Autogen: Adaptive missing Qt warning

This makes the warning message for a missing Qt use
the requested Qt version in the message text.

Source/cmQtAutoGenGlobalInitializer.cxx

@@ -85,8 +85,8 @@ cmQtAutoGenGlobalInitializer::cmQtAutoGenGlobalInitializer(
 
         // We support Qt4, Qt5 and Qt6
         auto qtVersion = cmQtAutoGenInitializer::GetQtVersion(target);
-        bool const validQt = (qtVersion.Major == 4) ||
-          (qtVersion.Major == 5) || (qtVersion.Major == 6);
+        bool const validQt = (qtVersion.first.Major == 4) ||
+          (qtVersion.first.Major == 5) || (qtVersion.first.Major == 6);
 
         bool const mocAvailable = (validQt || !mocExec.empty());
         bool const uicAvailable = (validQt || !uicExec.empty());
@@ -104,10 +104,16 @@ cmQtAutoGenGlobalInitializer::cmQtAutoGenGlobalInitializer(
           msg += ". ";
           msg += cmQtAutoGen::Tools(mocDisabled, uicDisabled, rccDisabled);
           msg += " disabled.  Consider adding:\n";
-          if (uicDisabled) {
-            msg += "  find_package(Qt5 COMPONENTS Widgets)\n";
-          } else {
-            msg += "  find_package(Qt5 COMPONENTS Core)\n";
+          {
+            std::string version = (qtVersion.second == 0)
+              ? std::string("<QTVERSION>")
+              : std::to_string(qtVersion.second);
+            std::string comp = uicDisabled ? "Widgets" : "Core";
+            msg += "  find_package(Qt";
+            msg += version;
+            msg += " COMPONENTS ";
+            msg += comp;
+            msg += ")\n";
           }
           msg += "to your CMakeLists.txt file.";
           target->Makefile->IssueMessage(cmake::AUTHOR_WARNING, msg);
@@ -115,7 +121,7 @@ cmQtAutoGenGlobalInitializer::cmQtAutoGenGlobalInitializer(
         if (mocIsValid || uicIsValid || rccIsValid) {
           // Create autogen target initializer
           Initializers_.emplace_back(cm::make_unique<cmQtAutoGenInitializer>(
-            this, target, qtVersion, mocIsValid, uicIsValid, rccIsValid,
+            this, target, qtVersion.first, mocIsValid, uicIsValid, rccIsValid,
             globalAutoGenTarget, globalAutoRccTarget));
         }
       }

Source/cmQtAutoGenInitializer.cxx

@@ -1409,32 +1409,31 @@ static std::vector<cmQtAutoGenInitializer::IntegerVersion> GetKnownQtVersions(
   return result;
 }
 
-cmQtAutoGenInitializer::IntegerVersion cmQtAutoGenInitializer::GetQtVersion(
-  cmGeneratorTarget const* target)
+std::pair<cmQtAutoGenInitializer::IntegerVersion, unsigned int>
+cmQtAutoGenInitializer::GetQtVersion(cmGeneratorTarget const* target)
 {
-  auto knownQtVersions = GetKnownQtVersions(target);
-  if (knownQtVersions.empty()) {
-    return cmQtAutoGenInitializer::IntegerVersion(); // No Qt
-  }
-
-  // Pick a version from the known versions:
-  auto targetVersion = CharPtrToInt(
-    target->GetLinkInterfaceDependentStringProperty("QT_MAJOR_VERSION", ""));
+  std::pair<IntegerVersion, unsigned int> res(
+    IntegerVersion(),
+    CharPtrToInt(target->GetLinkInterfaceDependentStringProperty(
+      "QT_MAJOR_VERSION", "")));
 
-  if (targetVersion == 0) {
-    // No specific version was requested by the target:
-    // Use highest known Qt version.
-    return knownQtVersions.at(0);
-  }
-
-  for (auto it : knownQtVersions) {
-    if (it.Major == targetVersion) {
-      return it;
+  auto knownQtVersions = GetKnownQtVersions(target);
+  if (!knownQtVersions.empty()) {
+    if (res.second == 0) {
+      // No specific version was requested by the target:
+      // Use highest known Qt version.
+      res.first = knownQtVersions.at(0);
+    } else {
+      // Pick a version from the known versions:
+      for (auto it : knownQtVersions) {
+        if (it.Major == res.second) {
+          res.first = it;
+          break;
+        }
+      }
     }
   }
-
-  // Requested version was not found
-  return cmQtAutoGenInitializer::IntegerVersion();
+  return res;
 }
 
 std::pair<bool, std::string> GetQtExecutable(

Source/cmQtAutoGenInitializer.h

@@ -11,6 +11,7 @@
 #include <ostream>
 #include <set>
 #include <string>
+#include <utility>
 #include <vector>
 
 class cmGeneratorTarget;
@@ -76,7 +77,9 @@ public:
   };
 
 public:
-  static IntegerVersion GetQtVersion(cmGeneratorTarget const* target);
+  /// @return The detected Qt version and the required Qt major version
+  static std::pair<IntegerVersion, unsigned int> GetQtVersion(
+    cmGeneratorTarget const* target);
 
   cmQtAutoGenInitializer(cmQtAutoGenGlobalInitializer* globalInitializer,
                          cmGeneratorTarget* target,

Tests/RunCMake/Autogen/NoQt-stderr.txt

@@ -2,7 +2,7 @@
   AUTOGEN: No valid Qt version found for target main.  AUTOMOC, AUTOUIC and
   AUTORCC disabled.  Consider adding:
 
-    find_package\(Qt5 COMPONENTS Widgets\)
+    find_package\(Qt<QTVERSION> COMPONENTS Widgets\)
 
   to your CMakeLists.txt file.
 This warning is for project developers.  Use -Wno-dev to suppress it.