clang-cl: Warn about /U flags that look like filenames (PR31662)

Both on Mac and Windows, it's common to have a 'Users' directory in the
root of the filesystem, so one might specify a filename as
'/Users/me/myfile.c'. clang-cl (as well as MSVC's cl.exe) will interpret
that as invoking the '/U' option, which is probably not what the user
wanted. Add a warning about this.

Differential Revision: https://reviews.llvm.org/D29198

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@293305 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 2fcd3a5a2fbaa9e706096b22823728ca39de6b29..596ef273a262b609e59b695ba57050e9305e0c67 100644 (file)
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -247,6 +247,10 @@ def err_test_module_file_extension_format : Error<
 def warn_drv_invoking_fallback : Warning<"falling back to %0">,
   InGroup<Fallback>;
 
+def warn_slash_u_filename : Warning<"'/U%0' treated as the '/U' option">,
+  InGroup<DiagGroup<"slash-u-filename">>;
+def note_use_dashdash : Note<"Use '--' to treat subsequent arguments as filenames">;
+
 def err_drv_ropi_rwpi_incompatible_with_pic : Error<
   "embedded and GOT-based position independence are incompatible">;
 def err_drv_ropi_incompatible_with_cxx : Error<

diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index f16acbb42e94da5fc8e8ce94b36a3d8d69399c17..0dcab7c0c6c4889cf72c1454e1ef810999dfc2cd 100644 (file)
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -1583,6 +1583,14 @@ void Driver::BuildInputs(const ToolChain &TC, DerivedArgList &Args,
         Diag(clang::diag::err_drv_unknown_language) << A->getValue();
         InputType = types::TY_Object;
       }
+    } else if (A->getOption().getID() == options::OPT__SLASH_U) {
+      assert(A->getNumValues() == 1 && "The /U option has one value.");
+      StringRef Val = A->getValue(0);
+      if (Val.find_first_of("/\\") != StringRef::npos) {
+        // Warn about e.g. "/Users/me/myfile.c".
+        Diag(diag::warn_slash_u_filename) << Val;
+        Diag(diag::note_use_dashdash);
+      }
     }
   }
   if (CCCIsCPP() && Inputs.empty()) {

diff --git a/test/Driver/cl-options.c b/test/Driver/cl-options.c
index 69238227c542f5eb436b215bc94f0ac1a9f68a76..232cdce1078e02cf9e2be85cd041fd0de2492947 100644 (file)
--- a/test/Driver/cl-options.c
+++ b/test/Driver/cl-options.c
@@ -442,6 +442,12 @@
 // Xclang: "-cc1"
 // Xclang: "hellocc1"
 
+// Files under /Users are often confused with the /U flag. (This could happen
+// for other flags too, but this is the one people run into.)
+// RUN: %clang_cl /c /Users/me/myfile.c -### 2>&1 | FileCheck -check-prefix=SlashU %s
+// SlashU: warning: '/Users/me/myfile.c' treated as the '/U' option
+// SlashU: note: Use '--' to treat subsequent arguments as filenames
+
 // RTTI is on by default. /GR- controls -fno-rtti-data.
 // RUN: %clang_cl /c /GR- -### -- %s 2>&1 | FileCheck -check-prefix=NoRTTI %s
 // NoRTTI: "-fno-rtti-data"