gccrs: Add #[track_caller] as known attribute

gcc/rust/ChangeLog:

	* expand/rust-macro-builtins.cc (MacroBuiltin::builtin_transcribers):
	Add entry for track_caller.
	* util/rust-attribute-values.h: add `TRACK_CALLER` attribute.
	* util/rust-attributes.cc: add `track_caller` attribute definition.

gcc/testsuite/ChangeLog:

	* rust/compile/track_caller.rs: New test.

Signed-off-by: Bhavesh Mandalapu <mandalapubhavesh@gmail.com>

gcc/rust/expand/rust-macro-builtins.cc

@@ -137,6 +137,7 @@ std::unordered_map<std::string, AST::MacroTranscriberFunc>
     {"cfg_accessible", MacroBuiltin::sorry},
     {"rustc_const_stable", MacroBuiltin::sorry},
     {"rustc_const_unstable", MacroBuiltin::sorry},
+    {"track_caller", MacroBuiltin::sorry},
     /* Derive builtins do not need a real transcriber, but still need one. It
        should however never be called since builtin derive macros get expanded
        differently, and benefit from knowing on what kind of items they are

gcc/rust/util/rust-attribute-values.h

@@ -58,6 +58,7 @@ public:
   static constexpr auto &RUSTC_CONST_UNSTABLE = "rustc_const_unstable";
   static constexpr auto &MAY_DANGLE = "may_dangle";
   static constexpr auto &PRELUDE_IMPORT = "prelude_import";
+  static constexpr auto &TRACK_CALLER = "track_caller";
 };
 } // namespace Values
 } // namespace Rust

gcc/rust/util/rust-attributes.cc

@@ -75,7 +75,8 @@ static const BuiltinAttrDefinition __definitions[]
      // assuming we keep these for static analysis
      {Attrs::RUSTC_CONST_STABLE, STATIC_ANALYSIS},
      {Attrs::RUSTC_CONST_UNSTABLE, STATIC_ANALYSIS},
-     {Attrs::PRELUDE_IMPORT, NAME_RESOLUTION}};
+     {Attrs::PRELUDE_IMPORT, NAME_RESOLUTION},
+     {Attrs::TRACK_CALLER, CODE_GENERATION}};
 
 BuiltinAttributeMappings *
 BuiltinAttributeMappings::get ()

gcc/testsuite/rust/compile/track_caller.rs

@@ -0,0 +1,6 @@
+#[track_caller]
+fn foo() {}
+
+fn main() {
+    foo();
+}