Autogen: Pass explicit predefines header to moc if possible

Qt is relying on whoever calls moc to include a file with the predefined
values that will be used by the compiler, otherwise moc takes wrong
paths and weird things happen.
Instead, generate an include file and feed it to all mocs to make sure
it's generating correct code.

Co-Author: Sebastian Holtermann <sebholt@xwmw.org>
Fixes: #16640

6 files changed, 111 insertions, 5 deletions

diff --git a/Modules/AutogenInfo.cmake.in b/Modules/AutogenInfo.cmake.in
index fcecb6c..5e945bc 100644
--- a/Modules/AutogenInfo.cmake.in
+++ b/Modules/AutogenInfo.cmake.in
@@ -21,6 +21,7 @@ set(AM_MOC_INCLUDES @_moc_incs@)
 set(AM_MOC_OPTIONS @_moc_options@)
 set(AM_MOC_RELAXED_MODE @_moc_relaxed_mode@)
 set(AM_MOC_DEPEND_FILTERS @_moc_depend_filters@)
+set(AM_MOC_PREDEFS_CMD @_moc_predefs_cmd@)
 # UIC settings
 set(AM_UIC_SKIP @_uic_skip@)
 set(AM_UIC_TARGET_OPTIONS @_uic_target_options@)
diff --git a/Modules/Compiler/Intel.cmake b/Modules/Compiler/Intel.cmake
index 02968b4..06d01f1 100644
--- a/Modules/Compiler/Intel.cmake
+++ b/Modules/Compiler/Intel.cmake
@@ -22,5 +22,7 @@ else()
     string(APPEND CMAKE_${lang}_FLAGS_MINSIZEREL_INIT " -Os")
     string(APPEND CMAKE_${lang}_FLAGS_RELEASE_INIT " -O3")
     string(APPEND CMAKE_${lang}_FLAGS_RELWITHDEBINFO_INIT " -O2 -g")
+
+    set(CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "${CMAKE_${lang}_COMPILER}" "-QdM" "-P" "-Za" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
   endmacro()
 endif()
diff --git a/Modules/Platform/Linux-GNU.cmake b/Modules/Platform/Linux-GNU.cmake
index 6878254..ce30a26 100644
--- a/Modules/Platform/Linux-GNU.cmake
+++ b/Modules/Platform/Linux-GNU.cmake
@@ -12,4 +12,5 @@ macro(__linux_compiler_gnu lang)
   # We pass this for historical reasons.  Projects may have
   # executables that use dlopen but do not set ENABLE_EXPORTS.
   set(CMAKE_SHARED_LIBRARY_LINK_${lang}_FLAGS "-rdynamic")
+  set(CMAKE_${lang}_COMPILER_PREDEFINES_COMMAND "${CMAKE_${lang}_COMPILER}" "-dM" "-E" "-c" "${CMAKE_ROOT}/Modules/CMakeCXXCompilerABI.cpp")
 endmacro()
diff --git a/Source/cmQtAutoGeneratorInitializer.cxx b/Source/cmQtAutoGeneratorInitializer.cxx
index d69794c..c7e02e6 100644
--- a/Source/cmQtAutoGeneratorInitializer.cxx
+++ b/Source/cmQtAutoGeneratorInitializer.cxx
@@ -96,6 +96,41 @@ static std::string GetQtMajorVersion(cmGeneratorTarget const* target)
   return qtMajorVersion;
 }
 
+static std::string GetQtMinorVersion(cmGeneratorTarget const* target,
+                                     const std::string& qtMajorVersion)
+{
+  cmMakefile* makefile = target->Target->GetMakefile();
+  std::string qtMinorVersion;
+  if (qtMajorVersion == "5") {
+    qtMinorVersion = makefile->GetSafeDefinition("Qt5Core_VERSION_MINOR");
+  }
+  if (qtMinorVersion.empty()) {
+    qtMinorVersion = makefile->GetSafeDefinition("QT_VERSION_MINOR");
+  }
+
+  const char* targetQtVersion =
+    target->GetLinkInterfaceDependentStringProperty("QT_MINOR_VERSION", "");
+  if (targetQtVersion != CM_NULLPTR) {
+    qtMinorVersion = targetQtVersion;
+  }
+  return qtMinorVersion;
+}
+
+static bool QtVersionGreaterOrEqual(const std::string& major,
+                                    const std::string& minor,
+                                    unsigned long requestMajor,
+                                    unsigned long requestMinor)
+{
+  unsigned long majorUL(0);
+  unsigned long minorUL(0);
+  if (cmSystemTools::StringToULong(major.c_str(), &majorUL) &&
+      cmSystemTools::StringToULong(minor.c_str(), &minorUL)) {
+    return (majorUL > requestMajor) ||
+      (majorUL == requestMajor && minorUL >= requestMinor);
+  }
+  return false;
+}
+
 static void GetCompileDefinitionsAndDirectories(
   cmGeneratorTarget const* target, const std::string& config,
   std::string& incs, std::string& defs)
@@ -258,6 +293,12 @@ static void MocSetupAutoTarget(
   AddDefinitionEscaped(makefile, "_moc_depend_filters",
                        GetSafeProperty(target, "AUTOMOC_DEPEND_FILTERS"));
 
+  if (QtVersionGreaterOrEqual(
+        qtMajorVersion, GetQtMinorVersion(target, qtMajorVersion), 5, 8)) {
+    AddDefinitionEscaped(
+      makefile, "_moc_predefs_cmd",
+      makefile->GetSafeDefinition("CMAKE_CXX_COMPILER_PREDEFINES_COMMAND"));
+  }
   // Moc includes and compile definitions
   {
     std::string _moc_incs;
diff --git a/Source/cmQtAutoGenerators.cxx b/Source/cmQtAutoGenerators.cxx
index 246dd8d..875062c 100644
--- a/Source/cmQtAutoGenerators.cxx
+++ b/Source/cmQtAutoGenerators.cxx
@@ -360,6 +360,8 @@ bool cmQtAutoGenerators::ReadAutogenInfoFile(
   InfoGet(makefile, "AM_QT_MOC_EXECUTABLE", this->MocExecutable);
   InfoGet(makefile, "AM_QT_UIC_EXECUTABLE", this->UicExecutable);
   InfoGet(makefile, "AM_QT_RCC_EXECUTABLE", this->RccExecutable);
+
+  InfoGet(makefile, "AM_MOC_PREDEFS_CMD", this->MocPredefsCmd);
   // Check Qt version
   if ((this->QtMajorVersion != "4") && (this->QtMajorVersion != "5")) {
     this->LogError("AutoGen: Error: Unsupported Qt version: " +
@@ -579,6 +581,12 @@ void cmQtAutoGenerators::Init(cmMakefile* makefile)
 
   this->MocCppFilenameAbs = this->CurrentBinaryDir + this->MocCppFilenameRel;
 
+  // Moc predefs file
+  if (!this->MocPredefsCmd.empty()) {
+    this->MocPredefsFileRel = this->AutogenBuildSubDir + "moc_predefs.h";
+    this->MocPredefsFileAbs = this->CurrentBinaryDir + this->MocPredefsFileRel;
+  }
+
   // Init file path checksum generator
   fpathCheckSum.setupParentDirs(this->CurrentSourceDir, this->CurrentBinaryDir,
                                 this->ProjectSourceDir,
@@ -1142,6 +1150,50 @@ bool cmQtAutoGenerators::MocGenerateAll(
     return true;
   }
 
+  // Generate moc_predefs
+  if (!this->MocPredefsCmd.empty()) {
+    if (!this->MakeParentDirectory(this->MocPredefsFileAbs)) {
+      this->LogError("AutoMoc: Error creating directory for " +
+                     this->MocPredefsFileRel);
+      return false;
+    }
+    this->LogBold("Generating MOC predefs " + this->MocPredefsFileRel);
+
+    std::vector<std::string> cmd = this->MocPredefsCmd;
+    cmd.insert(cmd.end(), this->MocIncludes.begin(), this->MocIncludes.end());
+    for (std::vector<std::string>::const_iterator it =
+           this->MocDefinitions.begin();
+         it != this->MocDefinitions.end(); ++it) {
+      cmd.push_back("-D" + (*it));
+    }
+    cmd.insert(cmd.end(), this->MocOptions.begin(), this->MocOptions.end());
+
+    std::string output;
+    bool moc_predefsGenerated = this->RunCommand(cmd, output, false);
+    if (!moc_predefsGenerated) {
+      return false;
+    }
+
+    // actually write the file
+    cmsys::ofstream outfile;
+    outfile.open(this->MocPredefsFileAbs.c_str(), std::ios::trunc);
+    if (!outfile) {
+      moc_predefsGenerated = false;
+      this->LogError("AutoMoc: Error opening " + this->MocPredefsFileRel);
+    } else {
+      outfile << output;
+      // Check for write errors
+      if (!outfile.good()) {
+        moc_predefsGenerated = false;
+        this->LogError("AutoMoc: Error writing " + this->MocPredefsFileRel);
+      }
+    }
+
+    if (!moc_predefsGenerated) {
+      return false;
+    }
+  }
+
   bool mocCompFileGenerated = false;
   bool mocCompChanged = false;
 
@@ -1305,6 +1357,10 @@ bool cmQtAutoGenerators::MocGenerateFile(
         cmd.push_back("-D" + (*it));
       }
       cmd.insert(cmd.end(), this->MocOptions.begin(), this->MocOptions.end());
+      if (!this->MocPredefsFileAbs.empty()) {
+        cmd.push_back("--include");
+        cmd.push_back(this->MocPredefsFileAbs);
+      }
 #ifdef _WIN32
       cmd.push_back("-DWIN32");
 #endif
@@ -1805,7 +1861,7 @@ bool cmQtAutoGenerators::MakeParentDirectory(const std::string& filename) const
  * @return True on success
  */
 bool cmQtAutoGenerators::RunCommand(const std::vector<std::string>& command,
-                                    std::string& output) const
+                                    std::string& output, bool verbose) const
 {
   // Log command
   if (this->Verbose) {
@@ -1813,8 +1869,9 @@ bool cmQtAutoGenerators::RunCommand(const std::vector<std::string>& command,
   }
   // Execute command
   int retVal = 0;
-  bool res =
-    cmSystemTools::RunSingleCommand(command, &output, &output, &retVal);
+  bool res = cmSystemTools::RunSingleCommand(
+    command, &output, &output, &retVal, CM_NULLPTR,
+    verbose ? cmSystemTools::OUTPUT_MERGE : cmSystemTools::OUTPUT_NONE);
   return (res && (retVal == 0));
 }
 
diff --git a/Source/cmQtAutoGenerators.h b/Source/cmQtAutoGenerators.h
index ee046de..cb6f45a 100644
--- a/Source/cmQtAutoGenerators.h
+++ b/Source/cmQtAutoGenerators.h
@@ -142,8 +142,8 @@ private:
                              const char* basePrefix,
                              const char* baseSuffix) const;
   bool MakeParentDirectory(const std::string& filename) const;
-  bool RunCommand(const std::vector<std::string>& command,
-                  std::string& output) const;
+  bool RunCommand(const std::vector<std::string>& command, std::string& output,
+                  bool verbose = true) const;
 
   bool FindHeader(std::string& header, const std::string& testBasePath) const;
 
@@ -176,6 +176,8 @@ private:
   // - Moc
   std::string MocCppFilenameRel;
   std::string MocCppFilenameAbs;
+  std::string MocPredefsFileRel;
+  std::string MocPredefsFileAbs;
   std::vector<std::string> MocSkipList;
   std::vector<std::string> MocIncludePaths;
   std::vector<std::string> MocIncludes;
@@ -197,6 +199,8 @@ private:
   MacroFilter MacroFilters[2];
   cmsys::RegularExpression RegExpMocInclude;
   cmsys::RegularExpression RegExpUicInclude;
+  // - moc_predefs
+  std::vector<std::string> MocPredefsCmd;
   // - Flags
   bool IncludeProjectDirsBefore;
   bool Verbose;