1 files changed, 74 insertions, 8 deletions

diff --git a/contrib/llvm/tools/clang/lib/Frontend/DependencyFile.cpp b/contrib/llvm/tools/clang/lib/Frontend/DependencyFile.cpp
index 6ea8f51..0995ab4 100644
--- a/contrib/llvm/tools/clang/lib/Frontend/DependencyFile.cpp
+++ b/contrib/llvm/tools/clang/lib/Frontend/DependencyFile.cpp
@@ -150,6 +150,8 @@ class DFGImpl : public PPCallbacks {
   bool AddMissingHeaderDeps;
   bool SeenMissingHeader;
   bool IncludeModuleFiles;
+  DependencyOutputFormat OutputFormat;
+
 private:
   bool FileMatchesDepCriteria(const char *Filename,
                               SrcMgr::CharacteristicKind FileType);
@@ -162,7 +164,8 @@ public:
       PhonyTarget(Opts.UsePhonyTargets),
       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps),
       SeenMissingHeader(false),
-      IncludeModuleFiles(Opts.IncludeModuleFiles) {}
+      IncludeModuleFiles(Opts.IncludeModuleFiles),
+      OutputFormat(Opts.OutputFormat) {}
 
   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
                    SrcMgr::CharacteristicKind FileType,
@@ -289,13 +292,76 @@ void DFGImpl::AddFilename(StringRef Filename) {
     Files.push_back(Filename);
 }
 
-/// PrintFilename - GCC escapes spaces, # and $, but apparently not ' or " or
-/// other scary characters.
-static void PrintFilename(raw_ostream &OS, StringRef Filename) {
+/// Print the filename, with escaping or quoting that accommodates the three
+/// most likely tools that use dependency files: GNU Make, BSD Make, and
+/// NMake/Jom.
+///
+/// BSD Make is the simplest case: It does no escaping at all.  This means
+/// characters that are normally delimiters, i.e. space and # (the comment
+/// character) simply aren't supported in filenames.
+///
+/// GNU Make does allow space and # in filenames, but to avoid being treated
+/// as a delimiter or comment, these must be escaped with a backslash. Because
+/// backslash is itself the escape character, if a backslash appears in a
+/// filename, it should be escaped as well.  (As a special case, $ is escaped
+/// as $$, which is the normal Make way to handle the $ character.)
+/// For compatibility with BSD Make and historical practice, if GNU Make
+/// un-escapes characters in a filename but doesn't find a match, it will
+/// retry with the unmodified original string.
+///
+/// GCC tries to accommodate both Make formats by escaping any space or #
+/// characters in the original filename, but not escaping backslashes.  The
+/// apparent intent is so that filenames with backslashes will be handled
+/// correctly by BSD Make, and by GNU Make in its fallback mode of using the
+/// unmodified original string; filenames with # or space characters aren't
+/// supported by BSD Make at all, but will be handled correctly by GNU Make
+/// due to the escaping.
+///
+/// A corner case that GCC gets only partly right is when the original filename
+/// has a backslash immediately followed by space or #.  GNU Make would expect
+/// this backslash to be escaped; however GCC escapes the original backslash
+/// only when followed by space, not #.  It will therefore take a dependency
+/// from a directive such as
+///     #include "a\ b\#c.h"
+/// and emit it as
+///     a\\\ b\\#c.h
+/// which GNU Make will interpret as
+///     a\ b\
+/// followed by a comment. Failing to find this file, it will fall back to the
+/// original string, which probably doesn't exist either; in any case it won't
+/// find
+///     a\ b\#c.h
+/// which is the actual filename specified by the include directive.
+///
+/// Clang does what GCC does, rather than what GNU Make expects.
+///
+/// NMake/Jom has a different set of scary characters, but wraps filespecs in
+/// double-quotes to avoid misinterpreting them; see
+/// https://msdn.microsoft.com/en-us/library/dd9y37ha.aspx for NMake info,
+/// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
+/// for Windows file-naming info.
+static void PrintFilename(raw_ostream &OS, StringRef Filename,
+                          DependencyOutputFormat OutputFormat) {
+  if (OutputFormat == DependencyOutputFormat::NMake) {
+    // Add quotes if needed. These are the characters listed as "special" to
+    // NMake, that are legal in a Windows filespec, and that could cause
+    // misinterpretation of the dependency string.
+    if (Filename.find_first_of(" #${}^!") != StringRef::npos)
+      OS << '\"' << Filename << '\"';
+    else
+      OS << Filename;
+    return;
+  }
+  assert(OutputFormat == DependencyOutputFormat::Make);
   for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
-    if (Filename[i] == ' ' || Filename[i] == '#')
+    if (Filename[i] == '#') // Handle '#' the broken gcc way.
+      OS << '\\';
+    else if (Filename[i] == ' ') { // Handle space correctly.
       OS << '\\';
-    else if (Filename[i] == '$') // $ is escaped by $$.
+      unsigned j = i;
+      while (j > 0 && Filename[--j] == '\\')
+        OS << '\\';
+    } else if (Filename[i] == '$') // $ is escaped by $$.
       OS << '$';
     OS << Filename[i];
   }
@@ -354,7 +420,7 @@ void DFGImpl::OutputDependencyFile() {
       Columns = 2;
     }
     OS << ' ';
-    PrintFilename(OS, *I);
+    PrintFilename(OS, *I, OutputFormat);
     Columns += N + 1;
   }
   OS << '\n';
@@ -365,7 +431,7 @@ void DFGImpl::OutputDependencyFile() {
     for (std::vector<std::string>::iterator I = Files.begin() + 1,
            E = Files.end(); I != E; ++I) {
       OS << '\n';
-      PrintFilename(OS, *I);
+      PrintFilename(OS, *I, OutputFormat);
       OS << ":\n";
     }
   }