If called as *cpp or *cpp-[^-]*, run only the preprocessor. If no
input is specified, use stdin implicitly. Based on a patch from
Roman Divacky.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@127137 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Driver/Driver.h b/include/clang/Driver/Driver.h
index 03fa0ef..dd91ea7 100644
--- a/include/clang/Driver/Driver.h
+++ b/include/clang/Driver/Driver.h
@@ -102,6 +102,9 @@
   /// Whether the driver should follow g++ like behavior.
   unsigned CCCIsCXX : 1;
 
+  /// Whether the driver is just the preprocessor
+  unsigned CCCIsCPP : 1;
+
   /// Echo commands while executing (in -v style).
   unsigned CCCEcho : 1;
 
@@ -221,7 +224,7 @@
   /// \param TC - The default host tool chain.
   /// \param Args - The input arguments.
   /// \param Actions - The list to store the resulting actions onto.
-  void BuildActions(const ToolChain &TC, const ArgList &Args,
+  void BuildActions(const ToolChain &TC, const InputArgList &Args,
                     ActionList &Actions) const;
 
   /// BuildUniversalActions - Construct the list of actions to perform
@@ -230,7 +233,7 @@
   /// \param TC - The default host tool chain.
   /// \param Args - The input arguments.
   /// \param Actions - The list to store the resulting actions onto.
-  void BuildUniversalActions(const ToolChain &TC, const ArgList &Args,
+  void BuildUniversalActions(const ToolChain &TC, const InputArgList &Args,
                              ActionList &Actions) const;
 
   /// BuildJobs - Bind actions to concrete tools and translate
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index ee225f2..c8300d3 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -308,10 +308,10 @@
 
   // Construct the list of abstract actions to perform for this compilation.
   if (Host->useDriverDriver())
-    BuildUniversalActions(C->getDefaultToolChain(), C->getArgs(),
+    BuildUniversalActions(C->getDefaultToolChain(), C->getInputArgs(),
                           C->getActions());
   else
-    BuildActions(C->getDefaultToolChain(), C->getArgs(), C->getActions());
+    BuildActions(C->getDefaultToolChain(), C->getInputArgs(), C->getActions());
 
   if (CCCPrintActions) {
     PrintActions(*C);
@@ -593,7 +593,7 @@
 }
 
 void Driver::BuildUniversalActions(const ToolChain &TC,
-                                   const ArgList &Args,
+                                   const InputArgList &Args,
                                    ActionList &Actions) const {
   llvm::PrettyStackTraceString CrashInfo("Building universal build actions");
   // Collect the list of architectures. Duplicates are allowed, but should only
@@ -688,7 +688,7 @@
   }
 }
 
-void Driver::BuildActions(const ToolChain &TC, const ArgList &Args,
+void Driver::BuildActions(const ToolChain &TC, const InputArgList &Args,
                           ActionList &Actions) const {
   llvm::PrettyStackTraceString CrashInfo("Building compilation actions");
   // Start by constructing the list of inputs and their types.
@@ -721,7 +721,7 @@
           //
           // Otherwise emit an error but still use a valid type to avoid
           // spurious errors (e.g., no inputs).
-          if (!Args.hasArgNoClaim(options::OPT_E))
+          if (!Args.hasArgNoClaim(options::OPT_E) && !CCCIsCPP)
             Diag(clang::diag::err_drv_unknown_stdin_type);
           Ty = types::TY_C;
         } else {
@@ -799,6 +799,15 @@
     }
   }
 
+  if (CCCIsCPP && Inputs.empty()) {
+    // If called as standalone preprocessor, stdin is processed
+    // if no other input is present.
+    unsigned Index = Args.MakeIndex("-");
+    Arg *A = Opts->ParseOneArg(Args, Index);
+    A->claim();
+    Inputs.push_back(std::make_pair(types::TY_C, A));
+  }
+
   if (!SuppressMissingInputWarning && Inputs.empty()) {
     Diag(clang::diag::err_drv_no_input_files);
     return;
@@ -811,7 +820,8 @@
   phases::ID FinalPhase;
 
   // -{E,M,MM} only run the preprocessor.
-  if ((FinalPhaseArg = Args.getLastArg(options::OPT_E)) ||
+  if (CCCIsCPP ||
+      (FinalPhaseArg = Args.getLastArg(options::OPT_E)) ||
       (FinalPhaseArg = Args.getLastArg(options::OPT_M, options::OPT_MM))) {
     FinalPhase = phases::Preprocess;
 
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 2f6a4cc..68439ce 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -41,7 +41,7 @@
 /// arguments that is shared with gcc.
 static void CheckPreprocessingOptions(const Driver &D, const ArgList &Args) {
   if (Arg *A = Args.getLastArg(options::OPT_C, options::OPT_CC))
-    if (!Args.hasArg(options::OPT_E))
+    if (!Args.hasArg(options::OPT_E) && !D.CCCIsCPP)
       D.Diag(clang::diag::err_drv_argument_only_allowed_with)
         << A->getAsString(Args) << "-E";
 }
@@ -2403,7 +2403,7 @@
   OutputArgs.push_back("-o");
   OutputArgs.push_back(Output.getFilename());
 
-  if (Args.hasArg(options::OPT_E)) {
+  if (Args.hasArg(options::OPT_E) || getToolChain().getDriver().CCCIsCPP) {
     AddCPPOptionsArgs(Args, CmdArgs, Inputs, OutputArgs);
   } else {
     AddCPPOptionsArgs(Args, CmdArgs, Inputs, ArgStringList());
diff --git a/tools/driver/driver.cpp b/tools/driver/driver.cpp
index 0b5d2c9..71baf8d 100644
--- a/tools/driver/driver.cpp
+++ b/tools/driver/driver.cpp
@@ -342,6 +342,11 @@
     TheDriver.CCCIsCXX = true;
   }
 
+  if (llvm::StringRef(ProgName).endswith("cpp") ||
+      llvm::StringRef(ProgName).rsplit('-').first.endswith("cpp")) {
+    TheDriver.CCCIsCPP = true;
+  }
+
   // Handle CC_PRINT_OPTIONS and CC_PRINT_OPTIONS_FILE.
   TheDriver.CCPrintOptions = !!::getenv("CC_PRINT_OPTIONS");
   if (TheDriver.CCPrintOptions)