Precompile headers: Add methods to generate PCH sources

Co-Author: Daniel Pfeifer <daniel@pfeifer-mail.de>

1 files changed, 110 insertions, 0 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 9e20b66..04738d8 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -21,6 +21,7 @@
 #include "cmCustomCommand.h"
 #include "cmCustomCommandGenerator.h"
 #include "cmCustomCommandLines.h"
+#include "cmGeneratedFileStream.h"
 #include "cmGeneratorExpression.h"
 #include "cmGeneratorExpressionContext.h"
 #include "cmGeneratorExpressionDAGChecker.h"
@@ -3355,6 +3356,115 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetPrecompileHeaders(
   return list;
 }
 
+std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
+                                            const std::string& language) const
+{
+  if (language != "C" && language != "CXX") {
+    return std::string();
+  }
+  if (this->GetPropertyAsBool("DISABLE_PRECOMPILE_HEADERS")) {
+    return std::string();
+  }
+  const auto inserted =
+    this->PchHeaders.insert(std::make_pair(language + config, ""));
+  if (inserted.second) {
+    const std::vector<BT<std::string>> headers =
+      this->GetPrecompileHeaders(config, language);
+    if (headers.empty()) {
+      return std::string();
+    }
+    std::string& filename = inserted.first->second;
+
+    if (this->GetGlobalGenerator()->IsMultiConfig()) {
+      filename =
+        cmStrCat(this->LocalGenerator->GetCurrentBinaryDirectory(), "/");
+    } else {
+      // For GCC we need to have the header file .h[xx]
+      // next to the .h[xx].gch file
+      filename = this->ObjectDirectory;
+    }
+
+    filename = cmStrCat(filename, "CMakeFiles/", this->GetName(),
+                        ".dir/cmake_pch", ((language == "C") ? ".h" : ".hxx"));
+
+    const std::string filename_tmp = cmStrCat(filename, ".tmp");
+    {
+      auto pchPrologue = this->Makefile->GetDefinition("CMAKE_PCH_PROLOGUE");
+      auto pchEpilogue = this->Makefile->GetDefinition("CMAKE_PCH_EPILOGUE");
+
+      cmGeneratedFileStream file(
+        filename_tmp, false,
+        this->GetGlobalGenerator()->GetMakefileEncoding());
+      file << "/* generated by CMake */\n\n";
+      if (pchPrologue) {
+        file << pchPrologue << "\n";
+      }
+      if (this->GetGlobalGenerator()->IsXcode()) {
+        file << "#ifndef CMAKE_SKIP_PRECOMPILE_HEADERS\n";
+      }
+      if (language == "CXX") {
+        file << "#ifdef __cplusplus\n";
+      }
+      for (auto const& header_bt : headers) {
+        if (header_bt.Value.empty()) {
+          continue;
+        }
+        if (header_bt.Value[0] == '<' || header_bt.Value[0] == '"') {
+          file << "#include " << header_bt.Value << "\n";
+        } else {
+          file << "#include \"" << header_bt.Value << "\"\n";
+        }
+      }
+      if (language == "CXX") {
+        file << "#endif // __cplusplus\n";
+      }
+      if (this->GetGlobalGenerator()->IsXcode()) {
+        file << "#endif // CMAKE_SKIP_PRECOMPILE_HEADERS\n";
+      }
+      if (pchEpilogue) {
+        file << pchEpilogue << "\n";
+      }
+    }
+    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
+    cmSystemTools::RemoveFile(filename_tmp);
+  }
+  return inserted.first->second;
+}
+
+std::string cmGeneratorTarget::GetPchSource(const std::string& config,
+                                            const std::string& language) const
+{
+  if (language != "C" && language != "CXX") {
+    return std::string();
+  }
+  const auto inserted =
+    this->PchSources.insert(std::make_pair(language + config, ""));
+  if (inserted.second) {
+    const std::string pchHeader = this->GetPchHeader(config, language);
+    if (pchHeader.empty()) {
+      return std::string();
+    }
+    std::string& filename = inserted.first->second;
+    filename = cmStrCat(this->LocalGenerator->GetCurrentBinaryDirectory(),
+                        "/CMakeFiles/", this->GetName(), ".dir/cmake_pch");
+
+    // For GCC the source extension will be tranformed into .h[xx].gch
+    if (!this->Makefile->IsOn("CMAKE_LINK_PCH")) {
+      filename += ((language == "C") ? ".h.c" : ".hxx.cxx");
+    } else {
+      filename += ((language == "C") ? ".c" : ".cxx");
+    }
+    const std::string filename_tmp = cmStrCat(filename, ".tmp");
+    {
+      cmGeneratedFileStream file(filename_tmp);
+      file << "/* generated by CMake */\n";
+    }
+    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
+    cmSystemTools::RemoveFile(filename_tmp);
+  }
+  return inserted.first->second;
+}
+
 void cmGeneratorTarget::GetLinkOptions(std::vector<std::string>& result,
                                        const std::string& config,
                                        const std::string& language) const