clang-cl: Better error message when trying to compile stdin (PR18640)

We should suggest using /Tc or /Tp to set the input type, instead of
erroneously suggesting -x, which isn't a clang-cl flag.

llvm-svn: 200362

3 files changed, 12 insertions, 1 deletions

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 59805b59ba2..dbc5ce994c6 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -17,6 +17,8 @@ def err_drv_unsupported_option_argument : Error<
   "unsupported argument '%1' to option '%0'">;
 def err_drv_unknown_stdin_type : Error<
   "-E or -x required when input is from standard input">;
+def err_drv_unknown_stdin_type_clang_cl : Error<
+  "use /Tc or /Tp to set input type for standard input">;
 def err_drv_unknown_language : Error<"language not recognized: '%0'">;
 def err_drv_invalid_arch_name : Error<
   "invalid arch name '%0'">;
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index ca3e50fd535..bd43fbeec19 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1030,7 +1030,8 @@ void Driver::BuildInputs(const ToolChain &TC, const DerivedArgList &Args,
           // Otherwise emit an error but still use a valid type to avoid
           // spurious errors (e.g., no inputs).
           if (!Args.hasArgNoClaim(options::OPT_E) && !CCCIsCPP())
-            Diag(clang::diag::err_drv_unknown_stdin_type);
+            Diag(IsCLMode() ? clang::diag::err_drv_unknown_stdin_type_clang_cl
+                            : clang::diag::err_drv_unknown_stdin_type);
           Ty = types::TY_C;
         } else {
           // Otherwise lookup by extension.
diff --git a/clang/test/Driver/cl-inputs.c b/clang/test/Driver/cl-inputs.c
index d6ee520257d..066e0e32d9f 100644
--- a/clang/test/Driver/cl-inputs.c
+++ b/clang/test/Driver/cl-inputs.c
@@ -33,3 +33,11 @@
 // WARN: warning: overriding '/TC' option with '/TP'
 // WARN: note: The last /TC or /TP option takes precedence over earlier instances
 // WARN-NOT: note
+
+// RUN: not %clang_cl - 2>&1 | FileCheck -check-prefix=STDIN %s
+// STDIN: error: use /Tc or /Tp
+
+// RUN: %clang_cl -### /Tc - 2>&1 | FileCheck -check-prefix=STDINTc %s
+// STDINTc: "-x" "c"
+
+void f();