[llvm-cov] Warn if -show-functions is used without query files

llvm-cov's report mode does not print any output when -show-functions is
specified and no source files are specified. This can be surprising, so
the tool should at least print out an error message when this happens.

rdar://problem/34636859

llvm-svn: 314175

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/tools/llvm-cov/CodeCoverage.cpp b/llvm/tools/llvm-cov/CodeCoverage.cpp
index ed87e9e8e61..1ea54a8cffd 100644
--- a/llvm/tools/llvm-cov/CodeCoverage.cpp
+++ b/llvm/tools/llvm-cov/CodeCoverage.cpp
@@ -931,10 +931,17 @@ int CodeCoverageTool::report(int argc, const char **argv,
     return 1;
 
   CoverageReport Report(ViewOpts, *Coverage.get());
-  if (!ShowFunctionSummaries)
+  if (!ShowFunctionSummaries) {
     Report.renderFileReports(llvm::outs());
-  else
+  } else {
+    if (SourceFiles.empty()) {
+      error("Source files must be specified when -show-functions=true is "
+            "specified");
+      return 1;
+    }
+
     Report.renderFunctionReports(SourceFiles, DC, llvm::outs());
+  }
   return 0;
 }