[RFC PATCH 08/11] rust: build: establish a baseline of lints across all crates

[Paolo Bonzini <pbonzini@redhat.com>]

Many lints that default to allow can be helpful in detecting bugs or
keeping the code style homogeneous.  Add them liberally, though perhaps
not as liberally as in hw/char/pl011/src/lib.rs.  In particular, enabling
entire groups can be problematic because of bitrot when new links are
added in the future.

For Clippy, this is actually a feature that is only present in Cargo
1.74.0 but, since we are not using Cargo to *build* QEMU, only developers
will need a new-enough cargo and only to run tools such as clippy.
The requirement does not apply to distros that are building QEMU.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/Cargo.toml               | 66 +++++++++++++++++++++++++++++++++++
 rust/hw/char/pl011/src/lib.rs | 18 ++--------
 rust/qemu-api/src/bindings.rs |  6 ++--
 3 files changed, 71 insertions(+), 19 deletions(-)

diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 1ff8f5c2781..43cca33a8d8 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -19,3 +19,69 @@ unknown_lints = "allow"
 
 # Prohibit code that is forbidden in Rust 2024
 unsafe_op_in_unsafe_fn = "deny"
+
+[workspace.lints.rustdoc]
+broken_intra_doc_links = "deny"
+invalid_html_tags = "deny"
+invalid_rust_codeblocks = "deny"
+bare_urls = "deny"
+unescaped_backticks = "deny"
+redundant_explicit_links = "deny"
+
+[workspace.lints.clippy]
+# default-warn lints
+result_unit_err = "allow"
+too_many_arguments = "allow"
+upper_case_acronyms = "allow"
+
+# default-allow lints
+as_ptr_cast_mut = "deny"
+as_underscore = "deny"
+assertions_on_result_states = "deny"
+bool_to_int_with_if = "deny"
+borrow_as_ptr = "deny"
+cast_lossless = "deny"
+dbg_macro = "deny"
+debug_assert_with_mut_call = "deny"
+derive_partial_eq_without_eq = "deny"
+doc_markdown = "deny"
+empty_structs_with_brackets = "deny"
+ignored_unit_patterns = "deny"
+implicit_clone = "deny"
+macro_use_imports = "deny"
+missing_const_for_fn = "deny"
+missing_safety_doc = "deny"
+multiple_crate_versions = "deny"
+mut_mut = "deny"
+needless_bitwise_bool = "deny"
+needless_pass_by_ref_mut = "deny"
+no_effect_underscore_binding = "deny"
+option_option = "deny"
+or_fun_call = "deny"
+ptr_as_ptr = "deny"
+ptr_cast_constness = "deny"
+pub_underscore_fields = "deny"
+redundant_clone = "deny"
+redundant_closure_for_method_calls = "deny"
+redundant_else = "deny"
+redundant_pub_crate = "deny"
+ref_binding_to_reference = "deny"
+ref_option_ref = "deny"
+return_self_not_must_use = "deny"
+same_name_method = "deny"
+semicolon_inside_block = "deny"
+significant_drop_in_scrutinee = "deny"
+significant_drop_tightening = "deny"
+suspicious_operation_groupings = "deny"
+transmute_ptr_to_ptr = "deny"
+transmute_undefined_repr = "deny"
+type_repetition_in_bounds = "deny"
+unused_self = "deny"
+used_underscore_binding = "deny"
+
+# nice to have, but cannot be enabled yet
+#wildcard_imports = "deny"
+
+# these may have false positives
+#option_if_let_else = "deny"
+cognitive_complexity = "deny"
diff --git a/rust/hw/char/pl011/src/lib.rs b/rust/hw/char/pl011/src/lib.rs
index cd0a49acb91..3fa178cded0 100644
--- a/rust/hw/char/pl011/src/lib.rs
+++ b/rust/hw/char/pl011/src/lib.rs
@@ -14,28 +14,14 @@
 //! the [`registers`] module for register types.
 
 #![deny(
-    rustdoc::broken_intra_doc_links,
-    rustdoc::redundant_explicit_links,
     clippy::correctness,
     clippy::suspicious,
     clippy::complexity,
     clippy::perf,
     clippy::cargo,
     clippy::nursery,
-    clippy::style,
-    // restriction group
-    clippy::dbg_macro,
-    clippy::as_underscore,
-    clippy::assertions_on_result_states,
-    // pedantic group
-    clippy::doc_markdown,
-    clippy::borrow_as_ptr,
-    clippy::cast_lossless,
-    clippy::option_if_let_else,
-    clippy::missing_const_for_fn,
-    clippy::cognitive_complexity,
-    clippy::missing_safety_doc,
-    )]
+    clippy::style
+)]
 #![allow(clippy::result_unit_err)]
 
 extern crate bilge;
diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs
index 1dac310594d..972b1f1ee90 100644
--- a/rust/qemu-api/src/bindings.rs
+++ b/rust/qemu-api/src/bindings.rs
@@ -7,10 +7,10 @@
     non_snake_case,
     non_upper_case_globals,
     unsafe_op_in_unsafe_fn,
+    clippy::pedantic,
+    clippy::restriction,
+    clippy::style,
     clippy::missing_const_for_fn,
-    clippy::too_many_arguments,
-    clippy::approx_constant,
-    clippy::use_self,
     clippy::useless_transmute,
     clippy::missing_safety_doc
 )]
-- 
2.47.0