Add optional coverage flags to build

This CL allows generating coverage information for the source files. By adding
use_coverage=true to the GN build settings clang will generate .gcno files for
each source file and executing the binary will generate a .gcda file for
each source file.

Those files can then be processed by llvm-cov to generate .gcov reports for each
source file.

i.e. (assuming use_coverage=true is set for out/coverage)
  * ninja -C out/coverage pdfium_unittests
  * cd out/coverage
  * find obj -name "*.o" -exec llvm-cov -af -stats {} > d.out \;

There should now be .gcov files for each source file in the out/coverage
directory.

Note, llvm-gcov may have a different name or syntax on your machine.

Change-Id: I7379579f5f20a5b8b2f3a3b409b868bba4b4d74d
Reviewed-on: https://pdfium-review.googlesource.com/2216
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

2 files changed, 12 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index fbede10eb0..fccc6d7900 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -42,6 +42,7 @@ config("pdfium_common_config") {
 
 config("pdfium_core_config") {
   cflags = []
+  ldflags = []
   configs = [ ":pdfium_common_config" ]
   defines = [ "V8_DEPRECATION_WARNINGS" ]
   if (is_linux) {
@@ -55,6 +56,14 @@ config("pdfium_core_config") {
   if (is_win) {
     cflags += [ "/wd4267" ]
   }
+  if (use_coverage && is_clang) {
+    cflags += [
+      "--coverage",
+      "-g",
+      "-O0",
+    ]
+    ldflags += [ "--coverage" ]
+  }
 }
 
 config("xfa_warnings") {
diff --git a/pdfium.gni b/pdfium.gni
index df051eca81..5737224f70 100644
--- a/pdfium.gni
+++ b/pdfium.gni
@@ -28,4 +28,7 @@ declare_args() {
 
   # Build PDFium standalone
   pdf_is_standalone = false
+
+  # Enable coverage information
+  use_coverage = false
 }