[llvm-cov] Use relative paths to file reports in -output-dir mode

This makes it possible to e.g copy a report to another filesystem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@274173 91177308-0d34-0410-b5e6-96231b3b80d8

Author: vedantk

test/tools/llvm-cov/double_dots.c

@@ -9,3 +9,9 @@
 // CHECK-NOT: coverage{{.*}}dots{{.*}}..{{.*}}dots
 
 int main() {}
+
+// Re-purpose this file to test that we use relative paths when creating
+// report indices:
+
+// RUN: FileCheck -check-prefix=REL-INDEX -input-file %t.dir/index.txt %s
+// REL-INDEX-NOT: %t.dir

tools/llvm-cov/SourceCoverageView.cpp

@@ -28,10 +28,14 @@ void CoveragePrinter::StreamDestructor::operator()(raw_ostream *OS) const {
 }
 
 std::string CoveragePrinter::getOutputPath(StringRef Path, StringRef Extension,
-                                           bool InToplevel) {
+                                           bool InToplevel, bool Relative) {
   assert(Extension.size() && "The file extension may not be empty");
 
-  SmallString<256> FullPath(Opts.ShowOutputDirectory);
+  SmallString<256> FullPath;
+
+  if (!Relative)
+    FullPath.append(Opts.ShowOutputDirectory);
+
   if (!InToplevel)
     sys::path::append(FullPath, getCoverageDir());
 
@@ -51,7 +55,7 @@ CoveragePrinter::createOutputStream(StringRef Path, StringRef Extension,
   if (!Opts.hasOutputDirectory())
     return OwnedStream(&outs());
 
-  std::string FullPath = getOutputPath(Path, Extension, InToplevel);
+  std::string FullPath = getOutputPath(Path, Extension, InToplevel, false);
 
   auto ParentDir = sys::path::parent_path(FullPath);
   if (auto E = sys::fs::create_directories(ParentDir))

tools/llvm-cov/SourceCoverageView.h

@@ -111,9 +111,11 @@ class CoveragePrinter {
 protected:
   CoveragePrinter(const CoverageViewOptions &Opts) : Opts(Opts) {}
 
-  /// \brief Return `OutputDir/ToplevelDir/Path.Extension`.
+  /// \brief Return `OutputDir/ToplevelDir/Path.Extension`. If \p InToplevel is
+  /// false, skip the ToplevelDir component. If \p Relative is false, skip the
+  /// OutputDir component.
   std::string getOutputPath(StringRef Path, StringRef Extension,
-                            bool InToplevel);
+                            bool InToplevel, bool Relative = true);
 
   /// \brief If directory output is enabled, create a file in that directory
   /// at the path given by getOutputPath(). Otherwise, return stdout.