Expose sysroot as a build variable

This cl removes hardcoded --sysroot flag generation from bazel when constructing
command line for C++ actions. The hardcoded flag is still exposed to Skylark (to
stay backwards compatible).

RELNOTES: None.
PiperOrigin-RevId: 168346711

2 files changed, 46 insertions, 0 deletions

diff --git a/tools/cpp/CROSSTOOL b/tools/cpp/CROSSTOOL
index b9b78f5c0b..0a96846be1 100644
--- a/tools/cpp/CROSSTOOL
+++ b/tools/cpp/CROSSTOOL
@@ -711,6 +711,7 @@ toolchain {
     }
     implies: 'legacy_compile_flags'
     implies: 'user_compile_flags'
+    implies: 'sysroot'
     implies: 'unfiltered_compile_flags'
   }
 
@@ -747,6 +748,7 @@ toolchain {
     }
     implies: 'legacy_compile_flags'
     implies: 'user_compile_flags'
+    implies: 'sysroot'
     implies: 'unfiltered_compile_flags'
   }
 
@@ -833,6 +835,27 @@ toolchain {
   }
 
   feature {
+    name: 'sysroot'
+    flag_set {
+      expand_if_all_available: 'sysroot'
+      action: 'assemble'
+      action: 'preprocess-assemble'
+      action: 'c-compile'
+      action: 'c++-compile'
+      action: 'c++-header-parsing'
+      action: 'c++-header-preprocessing'
+      action: 'c++-module-compile'
+      action: 'c++-module-codegen'
+      action: 'c++-link-executable'
+      action: 'c++-link-dynamic-library'
+      flag_group {
+        iterate_over: 'sysroot'
+        flag: '--sysroot=%{sysroot}'
+      }
+    }
+  }
+
+  feature {
     name: 'unfiltered_compile_flags'
     flag_set {
       expand_if_all_available: 'unfiltered_compile_flags'
diff --git a/tools/cpp/CROSSTOOL.tpl b/tools/cpp/CROSSTOOL.tpl
index 7b7630bd0b..f2dff43c63 100644
--- a/tools/cpp/CROSSTOOL.tpl
+++ b/tools/cpp/CROSSTOOL.tpl
@@ -284,6 +284,7 @@ toolchain {
     implies: 'msvc_env'
     implies: 'parse_showincludes'
     implies: 'user_compile_flags'
+    implies: 'sysroot'
     implies: 'unfiltered_compile_flags'
   }
 
@@ -323,6 +324,7 @@ toolchain {
     implies: 'msvc_env'
     implies: 'parse_showincludes'
     implies: 'user_compile_flags'
+    implies: 'sysroot'
     implies: 'unfiltered_compile_flags'
   }
 
@@ -897,6 +899,27 @@ toolchain {
   }
 
   feature {
+    name: 'sysroot'
+    flag_set {
+      expand_if_all_available: 'sysroot'
+      action: 'assemble'
+      action: 'preprocess-assemble'
+      action: 'c-compile'
+      action: 'c++-compile'
+      action: 'c++-header-parsing'
+      action: 'c++-header-preprocessing'
+      action: 'c++-module-compile'
+      action: 'c++-module-codegen'
+      action: 'c++-link-executable'
+      action: 'c++-link-dynamic-library'
+      flag_group {
+        iterate_over: 'sysroot'
+        flag: '--sysroot=%{sysroot}'
+      }
+    }
+  }
+
+  feature {
     name: 'unfiltered_compile_flags'
     flag_set {
       expand_if_all_available: 'unfiltered_compile_flags'