Add support for Assembler with C Preprocessor (.S) compilation

Specifically, the c module now provides the c.as-cpp submodules which can be
loaded in order to register the S{} target type and enable Assembler with C
Preprocessor compilation in the c compile rule. For details, refer to
"Assembler with C Preprocessor Compilation" in the manual.

1 files changed, 3 insertions, 1 deletions

diff --git a/libbuild2/c/init.hxx b/libbuild2/c/init.hxx
index f324c31..c3126ea 100644
--- a/libbuild2/c/init.hxx
+++ b/libbuild2/c/init.hxx
@@ -23,7 +23,9 @@ namespace build2
     // `c.config` -- loads c.guess and sets more variables.
     // `c`        -- loads c.config and registers target types and rules.
     // `c.objc`   -- registers m{} target type and enables Objective-C
-    //               compilation.
+    //               compilation. Must be loaded after c.
+    // `c.as-cpp` -- registers S{} target type and enables Assembler with
+    //               C preprocessor compilation. Must be loaded after c.
     //
     extern "C" LIBBUILD2_C_SYMEXPORT const module_functions*
     build2_c_load ();