Run C preprocessor

driver/cpreprocessor.cpp

@@ -0,0 +1,84 @@
+#include "driver/cpreprocessor.h"
+
+#include "dmd/errors.h"
+#include "driver/cl_options.h"
+#include "driver/tool.h"
+
+namespace {
+const char *getPathToImportc_h(const Loc &loc) {
+  // importc.h should be next to object.d
+  static const char *cached = nullptr;
+  if (!cached) {
+    cached = FileName::searchPath(global.path, "importc.h", false);
+    if (!cached) {
+      error(loc, "cannot find \"importc.h\" along import path");
+      fatal();
+    }
+  }
+  return cached;
+}
+} // anonymous namespace
+
+FileName runCPreprocessor(FileName csrcfile, const Loc &loc, bool &ifile,
+                          OutBuffer &defines) {
+  const char *importc_h = getPathToImportc_h(loc);
+  const char *ifilename = FileName::forceExt(csrcfile.toChars(), i_ext.ptr);
+
+  const auto &triple = *global.params.targetTriple;
+  const bool isMSVC = triple.isWindowsMSVCEnvironment();
+
+#if 0 //ifdef _WIN32
+  // TODO: INCLUDE env var etc.?
+  windows::MsvcEnvironmentScope msvcEnv;
+  if (isMSVC)
+    msvcEnv.setup();
+#endif
+
+  const std::string cc = getGcc(isMSVC ? "cl.exe" : "cc");
+  std::vector<std::string> args;
+
+  if (!isMSVC)
+    appendTargetArgsForGcc(args);
+
+  if (triple.isOSDarwin())
+    args.push_back("-fno-blocks"); // disable blocks extension
+
+  for (const auto &ccSwitch : opts::ccSwitches) {
+    args.push_back(ccSwitch);
+  }
+  // TODO: -Xcpp switches?
+
+  if (isMSVC) {
+    args.push_back("/P");               // run preprocessor
+    args.push_back("/Zc:preprocessor"); // use the new conforming preprocessor
+    args.push_back("/PD"); // undocumented: print all macro definitions
+    args.push_back("/nologo");
+    args.push_back(csrcfile.toChars());
+    args.push_back((llvm::Twine("/FI") + importc_h).str());
+    // preprocessed output file
+    args.push_back((llvm::Twine("/Fi") + ifilename).str());
+  } else { // Posix
+    // merge #define's with output:
+    // https://gcc.gnu.org/onlinedocs/cpp/Invocation.html#index-dD
+    args.push_back("-dD");
+
+    // need to redefine some macros in importc.h
+    args.push_back("-Wno-builtin-macro-redefined");
+
+    args.push_back("-E"); // run preprocessor only
+    args.push_back("-include");
+    args.push_back(importc_h);
+    args.push_back(csrcfile.toChars());
+    args.push_back("-o");
+    args.push_back(ifilename);
+  }
+
+  const int status = executeToolAndWait(loc, cc, args, global.params.verbose);
+  if (status) {
+    errorSupplemental(loc, "C preprocessor failed for file '%s'", csrcfile.toChars());
+    fatal();
+  }
+
+  ifile = true;
+  return FileName::create(ifilename);
+}