gccrs: diagnostic: Refactor Error class

The class now allows for more variants including a `Hint` one which
then gets emitted by calling `rust_inform`. This allows us to display
hints/tips/notes in backtracking contexts such as the parser.

gcc/rust/ChangeLog:

	* rust-diagnostics.h (struct Error): Add new Kind enum and various new
	static constructors to allow for hints as well.
	* rust-diagnostics.cc (Error::Error): Use new `kind` field properly.
	* checks/errors/privacy/rust-visibility-resolver.cc
	(VisibilityResolver::resolve_module_path): Use new Error API.
	* expand/rust-macro-builtins.cc (MacroBuiltin::include_handler): Likewise.
	* expand/rust-macro-expand.cc (parse_many): Likewise.
	(transcribe_type): Likewise.
	* parse/rust-parse-impl.h (Parser::parse_crate): Likewise.
	* rust-session-manager.cc (Session::handle_crate_name): Likewise.
	* ast/rust-ast.cc (Module::load_items): Likewise.

1 files changed, 39 insertions, 4 deletions

diff --git a/gcc/rust/rust-diagnostics.cc b/gcc/rust/rust-diagnostics.cc
index c0f02c2..4e5c2ec 100644
--- a/gcc/rust/rust-diagnostics.cc
+++ b/gcc/rust/rust-diagnostics.cc
@@ -231,14 +231,49 @@ rust_debug_loc (const Location location, const char *fmt, ...)
 }
 
 namespace Rust {
-Error::Error (const Location location, const char *fmt, ...) : locus (location)
+
+/**
+ * This function takes ownership of `args` and calls `va_end` on it
+ */
+static Error
+va_constructor (Error::Kind kind, Location locus, const char *fmt, va_list args)
+  RUST_ATTRIBUTE_GCC_DIAG (3, 0);
+
+static Error
+va_constructor (Error::Kind kind, Location locus, const char *fmt, va_list args)
+{
+  std::string message = expand_message (fmt, args);
+  message.shrink_to_fit ();
+  va_end (args);
+
+  return Error (kind, locus, message);
+}
+
+Error::Error (const Location location, const char *fmt, ...)
+  : kind (Kind::Err), locus (location)
 {
   va_list ap;
+  va_start (ap, fmt);
 
+  *this = va_constructor (Kind::Err, location, fmt, ap);
+}
+
+Error
+Error::Hint (const Location location, const char *fmt, ...)
+{
+  va_list ap;
   va_start (ap, fmt);
-  message = expand_message (fmt, ap);
-  va_end (ap);
 
-  message.shrink_to_fit ();
+  return va_constructor (Kind::Hint, location, fmt, ap);
+}
+
+Error
+Error::Fatal (const Location location, const char *fmt, ...)
+{
+  va_list ap;
+  va_start (ap, fmt);
+
+  return va_constructor (Kind::FatalErr, location, fmt, ap);
 }
+
 } // namespace Rust