[Driver] Add -fno-digraphs

Summary: Add a flag `-fno-digraphs` to disable digraphs in the lexer, similar to `-fno-operator-names` which disables alternative names for C++ operators.

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: rsmith, cfe-commits

Differential Revision: https://reviews.llvm.org/D48266

llvm-svn: 337232

4 files changed, 28 insertions, 2 deletions

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 5a7e5c9e4e5..9035a91ce21 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1335,6 +1335,10 @@ def fno_diagnostics_show_hotness : Flag<["-"], "fno-diagnostics-show-hotness">,
 def fno_diagnostics_show_option : Flag<["-"], "fno-diagnostics-show-option">, Group<f_Group>;
 def fno_diagnostics_show_note_include_stack : Flag<["-"], "fno-diagnostics-show-note-include-stack">,
     Flags<[CC1Option]>, Group<f_Group>;
+def fdigraphs : Flag<["-"], "fdigraphs">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Enable alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:' (default)">;
+def fno_digraphs : Flag<["-"], "fno-digraphs">, Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Disallow alternative token representations '<:', ':>', '<%', '%>', '%:', '%:%:'">;
 def fno_declspec : Flag<["-"], "fno-declspec">, Group<f_clang_Group>,
   HelpText<"Disallow __declspec as a keyword">, Flags<[CC1Option]>;
 def fno_dollars_in_identifiers : Flag<["-"], "fno-dollars-in-identifiers">, Group<f_Group>,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 472a4163e55..853f9a422f1 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3925,6 +3925,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // Forward -f (flag) options which we can pass directly.
   Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
   Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);
+  Args.AddLastArg(CmdArgs, options::OPT_fdigraphs, options::OPT_fno_digraphs);
   Args.AddLastArg(CmdArgs, options::OPT_fno_operator_names);
   Args.AddLastArg(CmdArgs, options::OPT_femulated_tls,
                   options::OPT_fno_emulated_tls);
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index f57f23a0d4c..d62429dc788 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2173,6 +2173,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.GNUKeywords = Args.hasFlag(OPT_fgnu_keywords, OPT_fno_gnu_keywords,
                                   Opts.GNUKeywords);
 
+  Opts.Digraphs = Args.hasFlag(OPT_fdigraphs, OPT_fno_digraphs, Opts.Digraphs);
+
   if (Args.hasArg(OPT_fno_operator_names))
     Opts.CXXOperatorNames = 0;
 
diff --git a/clang/test/Lexer/digraph.c b/clang/test/Lexer/digraph.c
index e940caf44f4..5d8a77d5395 100644
--- a/clang/test/Lexer/digraph.c
+++ b/clang/test/Lexer/digraph.c
@@ -1,6 +1,13 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -ffreestanding %s
-// expected-no-diagnostics
+// RUN: %clang_cc1 -DDIGRAPHS=1 -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -DDIGRAPHS=1 -fno-digraphs -fdigraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -fdigraphs -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -std=c89 -DDIGRAPHS=1 -fdigraphs -fsyntax-only -verify -ffreestanding %s
+// RUN: %clang_cc1 -std=c89 -fno-digraphs -fsyntax-only -verify -ffreestanding %s
+
+#if DIGRAPHS
 
+// expected-no-diagnostics
 %:include <stdint.h>
 
     %:ifndef BUFSIZE
@@ -14,3 +21,15 @@
             d<:len:> = s<:len:>;
         %>
     %>
+#else
+
+// expected-error@+1 {{expected identifier or '('}}
+%:include <stdint.h>
+;
+// expected-error@+1 {{expected ')'}} expected-note@+1{{to match this '('}}
+void copy(char d<::>);
+
+// expected-error@+1 {{expected function body}}
+void copy() <% %>
+
+#endif