[PATCH] D135389: [Clang] Emit a warning for ambiguous joined '-o' arguments

[Joseph Huber via Phabricator via cfe-commits]

jhuber6 created this revision.
jhuber6 added reviewers: jdoerfert, JonChesterfield, tra, jyknight, MaskRay, yaxunl, aaron.ballman, ronlieb.
Herald added a subscriber: StephenFan.
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The offloading toolchain makes heavy use of options beginning with
`--o`. This is problematic when combined with the joined `-o` flag. In
the following situation, the user will not get the expected output and
will not notice as the expected output will still be written.

  clang++ -x cuda foo.cu -offload-arch=sm_80 -o foo

This patch introduces a warning that checks for joined `-o` arguments
that would also be a valid driver argument if an additional `-` were
added. I believe this situation is uncommon enough to warrant a warning,
and can be trivially fixed by the end user by using the more common
separate form instead.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D135389

Files:
  clang/include/clang/Basic/DiagnosticDriverKinds.td
  clang/lib/Driver/Driver.cpp
  clang/test/Driver/unknown-arg.c


Index: clang/test/Driver/unknown-arg.c
===================================================================
--- clang/test/Driver/unknown-arg.c
+++ clang/test/Driver/unknown-arg.c
@@ -64,3 +64,9 @@
 // RUN: %clang -S %s -o %t.s  -Wunknown-to-clang-option 2>&1 | FileCheck --check-prefix=IGNORED %s
 
 // IGNORED: warning: unknown warning option '-Wunknown-to-clang-option'
+
+// RUN: %clang -### -offload-arch=sm_70 --offload-arch=sm_70 -offload-device-only -output -o foo \
+// RUN:   %s 2>&1 | FileCheck --check-prefix=O-WARN %s
+//      O-WARN: warning: joined argument treated as '-o ffload-arch=sm_70'; did you mean '--offload-arch=sm_70'?
+// O-WARN-NEXT: warning: joined argument treated as '-o ffload-device-only'; did you mean '--offload-device-only'?
+// O-WARN-NEXT: warning: joined argument treated as '-o utput'; did you mean '--output'?
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -327,6 +327,19 @@
                      DiagnosticsEngine::Warning;
   }
 
+  for (const Arg *A : Args.filtered(options::OPT_o)) {
+    if (ArgStrings[A->getIndex()] == A->getSpelling())
+      continue;
+
+    // Warn on joined arguments that are similar to a long argument.
+    auto ArgString = A->getAsString(Args);
+    std::string Nearest;
+    if (getOpts().findNearest("-" + ArgString, Nearest, IncludedFlagsBitmask,
+                              ExcludedFlagsBitmask) == 1)
+      Diags.Report(diag::warn_drv_potentially_misspelled_joined_argument)
+          << ArgString << Nearest;
+  }
+
   return Args;
 }
 
Index: clang/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -253,6 +253,9 @@
   "support for '/Yc' with more than one source file not implemented yet; flag ignored">,
   InGroup<ClangClPch>;
 
+def warn_drv_potentially_misspelled_joined_argument : Warning<
+  "joined argument treated as '%0'; did you mean '%1'?">, InGroup<UnknownArgument>;
+
 def err_drv_invalid_value : Error<"invalid value '%1' in '%0'">;
 def err_drv_invalid_int_value : Error<"invalid integral value '%1' in '%0'">;
 def err_drv_invalid_value_with_suggestion : Error<


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