Re: [PATCH 2/2] Experiment with adding an error code to an error

[David Malcolm via Gcc-patches]

On Wed, 2023-09-06 at 15:53 +0200, Arthur Cohen wrote:
> From: David Malcolm 

This is probably something for the gcc-rust maintainers to review
(rather than me self-reviewing with my "diagnostics maintainer" hat
on).

Doesn't have a ChangeLog entry, FWIW.
Doesn't have a signed-off-by, so here's one:

Signed-off-by: David Malcolm 

[...snip...]

> diff --git a/gcc/rust/rust-gcc-diagnostics.cc b/gcc/rust/rust-gcc-
> diagnostics.cc
> index 72d2c068541..58c0a5654ea 100644
> --- a/gcc/rust/rust-gcc-diagnostics.cc
> +++ b/gcc/rust/rust-gcc-diagnostics.cc

[...snip...]

> +void
> +rust_be_error_at (const RichLocation , const ErrorCode
> code,
> + const std::string )
> +{
> +  /* TODO: 'error_at' would like a non-'const' 'rich_location *'. 

The above comment should refer to "error_meta", rather than
"error_at"...

> */
> +  rich_location _loc = const_cast (location.get
> ());
> +  diagnostic_metadata m;
> +  rust_error_code_rule rule (code);
> +  m.add_rule (rule);
> +  error_meta (_loc, m, "%s", errmsg.c_str ());

... to match this call.

[...snip...]

Otherwise, LGTM, but as I said, this is more in the gcc-rust
maintainers' area.

Dave

[PATCH 2/2] Experiment with adding an error code to an error

[Arthur Cohen]

From: David Malcolm 

---
 gcc/rust/rust-diagnostics.cc  | 11 +++
 gcc/rust/rust-diagnostics.h   | 18 ++
 gcc/rust/rust-gcc-diagnostics.cc  | 33 +++
 gcc/rust/typecheck/rust-casts.cc  |  2 +-
 .../rust/compile/bad_as_bool_char.rs  |  4 +--
 5 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/gcc/rust/rust-diagnostics.cc b/gcc/rust/rust-diagnostics.cc
index 4e5c2ececd4..f29aec67652 100644
--- a/gcc/rust/rust-diagnostics.cc
+++ b/gcc/rust/rust-diagnostics.cc
@@ -166,6 +166,17 @@ rust_error_at (const Location location, const char *fmt, 
...)
   va_end (ap);
 }
 
+void
+rust_error_at (const RichLocation , const ErrorCode code,
+  const char *fmt, ...)
+{
+  va_list ap;
+
+  va_start (ap, fmt);
+  rust_be_error_at (location, code, expand_message (fmt, ap));
+  va_end (ap);
+}
+
 void
 rust_warning_at (const Location location, int opt, const char *fmt, ...)
 {
diff --git a/gcc/rust/rust-diagnostics.h b/gcc/rust/rust-diagnostics.h
index 43fee8baf4f..d198bd5736f 100644
--- a/gcc/rust/rust-diagnostics.h
+++ b/gcc/rust/rust-diagnostics.h
@@ -50,6 +50,18 @@
 
 // clang-format off
 // simple location
+
+struct ErrorCode
+{
+  explicit ErrorCode (const char *str) : m_str (str)
+  {
+gcc_assert (str);
+gcc_assert (str[0] == 'E');
+  }
+
+  const char *m_str;
+};
+
 extern void
 rust_internal_error_at (const Location, const char *fmt, ...)
   RUST_ATTRIBUTE_GCC_DIAG (2, 3)
@@ -72,6 +84,9 @@ rust_inform (const Location, const char *fmt, ...)
 extern void
 rust_error_at (const RichLocation &, const char *fmt, ...)
   RUST_ATTRIBUTE_GCC_DIAG (2, 3);
+extern void
+rust_error_at (const RichLocation &, const ErrorCode, const char *fmt, ...)
+  RUST_ATTRIBUTE_GCC_DIAG (3, 4);
 // clang-format on
 
 // These interfaces provide a way for the front end to ask for
@@ -97,6 +112,9 @@ rust_be_error_at (const Location, const std::string );
 extern void
 rust_be_error_at (const RichLocation &, const std::string );
 extern void
+rust_be_error_at (const RichLocation &, const ErrorCode,
+ const std::string );
+extern void
 rust_be_warning_at (const Location, int opt, const std::string );
 extern void
 rust_be_fatal_error (const Location, const std::string )
diff --git a/gcc/rust/rust-gcc-diagnostics.cc b/gcc/rust/rust-gcc-diagnostics.cc
index 72d2c068541..58c0a5654ea 100644
--- a/gcc/rust/rust-gcc-diagnostics.cc
+++ b/gcc/rust/rust-gcc-diagnostics.cc
@@ -22,6 +22,7 @@
 #include "rust-diagnostics.h"
 
 #include "options.h"
+#include "diagnostic-metadata.h"
 
 void
 rust_be_internal_error_at (const Location location, const std::string )
@@ -70,6 +71,38 @@ rust_be_error_at (const RichLocation , const 
std::string )
   error_at (_loc, "%s", errmsg.c_str ());
 }
 
+class rust_error_code_rule : public diagnostic_metadata::rule
+{
+public:
+  rust_error_code_rule (const ErrorCode code) : m_code (code) {}
+
+  char *make_description () const final override
+  {
+return xstrdup (m_code.m_str);
+  }
+
+  char *make_url () const final override
+  {
+return concat ("https://doc.rust-lang.org/error-index.html#;, m_code.m_str,
+  NULL);
+  }
+
+private:
+  const ErrorCode m_code;
+};
+
+void
+rust_be_error_at (const RichLocation , const ErrorCode code,
+ const std::string )
+{
+  /* TODO: 'error_at' would like a non-'const' 'rich_location *'.  */
+  rich_location _loc = const_cast (location.get ());
+  diagnostic_metadata m;
+  rust_error_code_rule rule (code);
+  m.add_rule (rule);
+  error_meta (_loc, m, "%s", errmsg.c_str ());
+}
+
 void
 rust_be_get_quotechars (const char **open_qu, const char **close_qu)
 {
diff --git a/gcc/rust/typecheck/rust-casts.cc b/gcc/rust/typecheck/rust-casts.cc
index e379216b948..987542e59c4 100644
--- a/gcc/rust/typecheck/rust-casts.cc
+++ b/gcc/rust/typecheck/rust-casts.cc
@@ -283,7 +283,7 @@ TypeCastRules::emit_cast_error () const
   RichLocation r (locus);
   r.add_range (from.get_locus ());
   r.add_range (to.get_locus ());
-  rust_error_at (r, "invalid cast %<%s%> to %<%s%>",
+  rust_error_at (r, ErrorCode ("E0054"), "invalid cast %<%s%> to %<%s%>",
 from.get_ty ()->get_name ().c_str (),
 to.get_ty ()->get_name ().c_str ());
 }
diff --git a/gcc/testsuite/rust/compile/bad_as_bool_char.rs 
b/gcc/testsuite/rust/compile/bad_as_bool_char.rs
index 91a28eebe00..9652915fe11 100644
--- a/gcc/testsuite/rust/compile/bad_as_bool_char.rs
+++ b/gcc/testsuite/rust/compile/bad_as_bool_char.rs
@@ -5,13 +5,13 @@ pub fn main ()
   let fone = t as f32;   // { dg-error "invalid cast" }
   let fzero = f as f64;  // { dg-error "invalid cast" }
 
-  let nb = 0u8 as bool;  // { dg-error "invalid cast" }
+  let nb = 0u8 as bool;  // { dg-error "invalid cast .u8. to .bool. 
\\\[E0054\\\]" }
   let nc = true as char; // { dg-error "invalid cast" }
 
   let a = 'a';
   let b = 'b';
   let fa = a as f32; // { dg-error "invalid cast"