CMP0037: Allow test and package targets when features are not enabled

When CMake will not generate a test, package, or package_source target,
allow projects to create their own targets with these names.

Fixes: #16062

Source/cmGlobalGenerator.cxx

@@ -2220,6 +2220,45 @@ inline std::string removeQuotes(const std::string& s)
   return s;
 }
 
+bool cmGlobalGenerator::CheckCMP0037(std::string const& targetName,
+                                     std::string const& reason) const
+{
+  cmTarget* tgt = this->FindTarget(targetName);
+  if (!tgt) {
+    return true;
+  }
+  cmake::MessageType messageType = cmake::AUTHOR_WARNING;
+  std::ostringstream e;
+  bool issueMessage = false;
+  switch (tgt->GetPolicyStatusCMP0037()) {
+    case cmPolicies::WARN:
+      e << cmPolicies::GetPolicyWarning(cmPolicies::CMP0037) << "\n";
+      issueMessage = true;
+      CM_FALLTHROUGH;
+    case cmPolicies::OLD:
+      break;
+    case cmPolicies::NEW:
+    case cmPolicies::REQUIRED_IF_USED:
+    case cmPolicies::REQUIRED_ALWAYS:
+      issueMessage = true;
+      messageType = cmake::FATAL_ERROR;
+      break;
+  }
+  if (issueMessage) {
+    e << "The target name \"" << targetName << "\" is reserved " << reason
+      << ".";
+    if (messageType == cmake::AUTHOR_WARNING) {
+      e << "  It may result in undefined behavior.";
+    }
+    this->GetCMakeInstance()->IssueMessage(messageType, e.str(),
+                                           tgt->GetBacktrace());
+    if (messageType == cmake::FATAL_ERROR) {
+      return false;
+    }
+  }
+  return true;
+}
+
 void cmGlobalGenerator::CreateDefaultGlobalTargets(
   std::vector<GlobalTargetInfo>& targets)
 {
@@ -2241,6 +2280,14 @@ void cmGlobalGenerator::AddGlobalTarget_Package(
     return;
   }
 
+  const char* reservedTargets[] = { "package", "PACKAGE" };
+  for (const char* const* tn = cm::cbegin(reservedTargets);
+       tn != cm::cend(reservedTargets); ++tn) {
+    if (!this->CheckCMP0037(*tn, "when CPack packaging is enabled")) {
+      return;
+    }
+  }
+
   const char* cmakeCfgIntDir = this->GetCMakeCFGIntDir();
   GlobalTargetInfo gti;
   gti.Name = this->GetPackageTargetName();
@@ -2284,6 +2331,14 @@ void cmGlobalGenerator::AddGlobalTarget_PackageSource(
     return;
   }
 
+  const char* reservedTargets[] = { "package_source" };
+  for (const char* const* tn = cm::cbegin(reservedTargets);
+       tn != cm::cend(reservedTargets); ++tn) {
+    if (!this->CheckCMP0037(*tn, "when CPack source packaging is enabled")) {
+      return;
+    }
+  }
+
   GlobalTargetInfo gti;
   gti.Name = packageSourceTargetName;
   gti.Message = "Run CPack packaging tool for source...";
@@ -2307,6 +2362,14 @@ void cmGlobalGenerator::AddGlobalTarget_Test(
     return;
   }
 
+  const char* reservedTargets[] = { "test", "RUN_TESTS" };
+  for (const char* const* tn = cm::cbegin(reservedTargets);
+       tn != cm::cend(reservedTargets); ++tn) {
+    if (!this->CheckCMP0037(*tn, "when CTest testing is enabled")) {
+      return;
+    }
+  }
+
   const char* cmakeCfgIntDir = this->GetCMakeCFGIntDir();
   GlobalTargetInfo gti;
   gti.Name = this->GetTestTargetName();
@@ -2590,11 +2653,10 @@ bool cmGlobalGenerator::IsReservedTarget(std::string const& name)
   // by one or more of the cmake generators.
 
   // Adding additional targets to this list will require a policy!
-  const char* reservedTargets[] = {
-    "all",        "ALL_BUILD", "help",       "install",        "INSTALL",
-    "preinstall", "clean",     "edit_cache", "rebuild_cache",  "test",
-    "RUN_TESTS",  "package",   "PACKAGE",    "package_source", "ZERO_CHECK"
-  };
+  const char* reservedTargets[] = { "all",       "ALL_BUILD",  "help",
+                                    "install",   "INSTALL",    "preinstall",
+                                    "clean",     "edit_cache", "rebuild_cache",
+                                    "ZERO_CHECK" };
 
   return std::find(cm::cbegin(reservedTargets), cm::cend(reservedTargets),
                    name) != cm::cend(reservedTargets);

Source/cmGlobalGenerator.h

@@ -568,6 +568,9 @@ private:
 
   void ClearGeneratorMembers();
 
+  bool CheckCMP0037(std::string const& targetName,
+                    std::string const& reason) const;
+
   void IndexMakefile(cmMakefile* mf);
 
   virtual const char* GetBuildIgnoreErrorsFlag() const { return nullptr; }

Source/cmPolicies.h

@@ -225,6 +225,7 @@ class cmMakefile;
   F(CMP0021)                                                                  \
   F(CMP0022)                                                                  \
   F(CMP0027)                                                                  \
+  F(CMP0037)                                                                  \
   F(CMP0038)                                                                  \
   F(CMP0041)                                                                  \
   F(CMP0042)                                                                  \