build: Remove sanitizer_keep_symbols and sanitizer_no_symbols flags.

As far as I can tell, both of these flags just mean "respect
symbol_level when sanitizers are enabled". This change makes it so
that we always do that, removing the need for both flags. Because
the default symbol level is 1 in sanitizer builds, we still get -g1
(which is equivalent to -gline-tables-only) by default. Users can
now adjust the symbol level simply by setting symbol_level.

Change-Id: Ied9f589c268e7e5c625b4cce46d76e51452e473b
Reviewed-on: https://chromium-review.googlesource.com/1156125Reviewed-by: Oliver Chang <ochang@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Peter Collingbourne <pcc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579330}

build/config/compiler/compiler.gni

@@ -209,7 +209,9 @@ if (symbol_level == -1) {
     # them off, but keep them on for Official builds and Chromecast builds.
     symbol_level = 2
   } else if (using_sanitizer) {
-    # Sanitizers require symbols for filename suppressions to work.
+    # Sanitizers need line table info for stack traces. They don't need type
+    # info or variable info, so we can leave that out to speed up the build.
+    # Sanitizers also require symbols for filename suppressions to work.
     symbol_level = 1
   } else {
     symbol_level = 0

build/config/sanitizers/BUILD.gn

@@ -249,25 +249,16 @@ config("default_sanitizer_ldflags") {
 config("common_sanitizer_flags") {
   cflags = []
 
-  # Sanitizers need line table info for stack traces. They don't need type info
-  # or variable info, so we can leave that out to speed up the build (unless
-  # it's explicitly asked for by setting |sanitizer_keep_symbols| to true).
   if (using_sanitizer) {
     assert(is_clang, "sanitizers only supported with clang")
     assert(!is_official_build, "sanitizers not supported in official builds")
 
-    if (!sanitizer_no_symbols) {
-      if (!sanitizer_keep_symbols) {
-        cflags += [ "-gline-tables-only" ]
-      }
-
-      cflags += [
-        # Column info in debug data confuses Visual Studio's debugger, so don't
-        # use this by default.  However, clusterfuzz needs it for good
-        # attribution of reports to CLs, so turn it on there.
-        "-gcolumn-info",
-      ]
-    }
+    cflags += [
+      # Column info in debug data confuses Visual Studio's debugger, so don't
+      # use this by default.  However, clusterfuzz needs it for good
+      # attribution of reports to CLs, so turn it on there.
+      "-gcolumn-info",
+    ]
 
     # Frame pointers are controlled in //build/config/compiler:default_stack_frames
   }

build/config/sanitizers/sanitizers.gni

@@ -102,16 +102,6 @@ declare_args() {
   # Default value when unset and use_sanitizer_coverage=true:
   #     trace-pc-guard,indirect-calls
   sanitizer_coverage_flags = ""
-
-  # Keep symbol level when building with sanitizers. When sanitizers are
-  # enabled, the default is to compile with the minimum debug info level
-  # necessary, overriding any other symbol level arguments that may be set.
-  # Setting this to true prevents this.
-  sanitizer_keep_symbols = false
-
-  # Builds fuzzer/sanitizers without symbols.  Use with symbol_level=0.
-  # Useful for reducing binary size when building with use_clang_coverage=true.
-  sanitizer_no_symbols = false
 }
 
 # Disable sanitizers for non-default toolchains.

testing/libfuzzer/getting_started.md

@@ -33,9 +33,8 @@ Supported sanitizer configurations are:
 | `is_ubsan_security=true` | enables [Undefined Behavior Sanitizer] to catch<sup>\[[*](reference.md#UBSan)\]</sup> undefined behavior like integer overflow. |
 | | it is possible to run libfuzzer without any sanitizers; *probably not what you want*.|
 
-Fuzz targets are built with minimal symbols by default, regardless of the value
-of `is_debug` and `symbol_level`. However if you want to run fuzz target under a
-debugger you can re-enable them by setting `sanitizer_keep_symbols=true`.
+Fuzz targets are built with minimal symbols by default. The symbol level
+can be adjusted in the usual way by setting `symbol_level`.
 
 To get the exact GN configuration that are used on our builders, see
 [Build Config].