clang-cl: Allow /Fo without an argument (PR21589)

When it's used without an argument, the default file name is
used. The same goes for /Fe.

Also, allow using /Fo, /Fa and /Fe with multiple inputs if they
don't have an argument.

llvm-svn: 222164

1 files changed, 4 insertions, 15 deletions

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 1794e8e7070..5d25ed77b98 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1165,11 +1165,8 @@ void Driver::BuildActions(const ToolChain &TC, DerivedArgList &Args,
   // Diagnose misuse of /Fo.
   if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fo)) {
     StringRef V = A->getValue();
-    if (V.empty()) {
-      // It has to have a value.
-      Diag(clang::diag::err_drv_missing_argument) << A->getSpelling() << 1;
-      Args.eraseArg(options::OPT__SLASH_Fo);
-    } else if (Inputs.size() > 1 && !llvm::sys::path::is_separator(V.back())) {
+    if (Inputs.size() > 1 && !V.empty() &&
+        !llvm::sys::path::is_separator(V.back())) {
       // Check whether /Fo tries to name an output file for multiple inputs.
       Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
         << A->getSpelling() << V;
@@ -1180,7 +1177,8 @@ void Driver::BuildActions(const ToolChain &TC, DerivedArgList &Args,
   // Diagnose misuse of /Fa.
   if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fa)) {
     StringRef V = A->getValue();
-    if (Inputs.size() > 1 && !llvm::sys::path::is_separator(V.back())) {
+    if (Inputs.size() > 1 && !V.empty() &&
+        !llvm::sys::path::is_separator(V.back())) {
       // Check whether /Fa tries to name an asm file for multiple inputs.
       Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
         << A->getSpelling() << V;
@@ -1188,15 +1186,6 @@ void Driver::BuildActions(const ToolChain &TC, DerivedArgList &Args,
     }
   }
 
-  // Diagnose misuse of /Fe.
-  if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fe)) {
-    if (A->getValue()[0] == '\0') {
-      // It has to have a value.
-      Diag(clang::diag::err_drv_missing_argument) << A->getSpelling() << 1;
-      Args.eraseArg(options::OPT__SLASH_Fe);
-    }
-  }
-
   // Diagnose misuse of /o.
   if (Arg *A = Args.getLastArg(options::OPT__SLASH_o)) {
     if (A->getValue()[0] == '\0') {