resolve: Rename "name bindings" to "name declarations" #150521

petrochenkov · 2025-12-30T21:00:34Z

This was discussed previously in some name resolution specification threads on zulip.
Link: #t-compiler/help > understanding early name resolution of imports @ 💬

The main change is that NameBinding is renamed to Decl.
The Name part is skipped because almost everything in rustc_resolve is about names.
So in general the naming looks more compact now (binding: NameBinding -> decl: Decl).

I didn't rename everything including all the local variables, but did rename most of significant interfaces.
Late resolution in particular uses "bindings" in slightly different meanings, I didn't touch that.

Also, some interface comments are added/improved.

Renaming list:

fn define_binding_local -> plant_decl_into_local_module
fn add_macro_use_binding -> add_macro_use_decl
fn binding_description -> decl_description
enum PendingBinding -> PendingDecl
field ImportKind::Single::bindings -> ImportKind::Single::decls
field NameResolution::non_glob_binding -> NameResolution::non_glob_decl
field NameResolution::glob_binding -> NameResolution::glob_decl
fn best_binding -> best_decl
fn import -> new_import_decl
fn try_define_local -> try_plant_decl_into_local_module
fn new_ambiguity_binding -> new_decl_with_ambiguity
fn new_warn_ambiguity_binding -> new_decl_with_warn_ambiguity
field UnnecessaryQualification::binding -> UnnecessaryQualification::decl
struct MacroRulesBinding -> MacroRulesDef
field MacroRulesBinding::binding -> MacroRulesDef::decl
variant MacroRulesScope::Binding -> MacroRulesScope::Def
enum LexicalScopeBinding -> LateDecl
variant LexicalScopeBinding::Item -> LateDecl::Decl
variant LexicalScopeBinding::Res -> LateDecl::RibDef
field ModuleData::self_binding -> ModuleData::self_decl
struct NameBindingData -> DeclData
type NameBinding -> Decl
enum NameBindingKind -> DeclKind
variant NameBindingKind::Res -> DeclKind::Def
field NameBindingKind::Import::binding -> DeclKind::Import::source_decl
field PrivacyError::binding -> PrivacyError::decl
field ExternPreludeEntry::item_binding -> ExternPreludeEntry::item_decl
field ExternPreludeEntry::flag_binding -> ExternPreludeEntry::flag_decl
field Resolver::binding_parent_modules -> Resolver::decl_parent_modules
field Resolver::dummy_binding -> Resolver::dummy_decl
field Resolver::builtin_types_bindings -> Resolver::builtin_type_decls
field Resolver::builtin_attrs_bindings -> Resolver::builtin_attr_decls
field Resolver::registered_tool_bindings -> Resolver::registered_tool_decls
fn ResolverArenas::new_res_binding -> ResolverArenas::new_def_decl
fn ResolverArenas::new_pub_res_binding -> ResolverArenas::new_pub_def_decl
fn ResolverArenas::alloc_name_binding -> ResolverArenas::alloc_decl
fn ResolverArenas::alloc_macro_rules_binding -> ResolverArenas::alloc_macro_rules_def
fn set_binding_parent_module -> set_decl_parent_module

rustbot · 2025-12-30T21:00:39Z

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petrochenkov · 2026-01-01T13:53:56Z

There are some cases in which I'm not sure in the naming.

E.g. what if something contains a name declaration that is known to always be a definition, should we call it "decl" or "def".
There's no consistency now, e.g. MacroRulesDef uses "def", and builtin_type_decls uses "decl".

Maybe if it contains the Decl type, then we should still use "decl" even if it's always a definition.
And it it contains something else, like Res, then we can use "def".
By that logic Rib::bindings (not touched in this PR) needs to be renamed to Rib::defs, which is a bit weird, but probably ok.

nnethercote · 2026-01-01T23:52:37Z

There are some cases in which I'm not sure in the naming.

I read over the commits and they seem fine to me, but I don't have any specific knowledge/opinions about all of this stuff.

@yaahc: you have been looking closely at this stuff lately. Any thoughts?

yaahc · 2026-01-05T22:42:26Z

There are some cases in which I'm not sure in the naming.

E.g. what if something contains a name declaration that is known to always be a definition, should we call it "decl" or "def". There's no consistency now, e.g. MacroRulesDef uses "def", and builtin_type_decls uses "decl".

Maybe if it contains the Decl type, then we should still use "decl" even if it's always a definition. And it it contains something else, like Res, then we can use "def". By that logic Rib::bindings (not touched in this PR) needs to be renamed to Rib::defs, which is a bit weird, but probably ok.

@yaahc: you have been looking closely at this stuff lately. Any thoughts?

I don't necessarily object to using the underlying types as a guide for which names to use in which case but that isn't how I'd think about it by default. Noting that I haven't spent a ton of time thinking about this and this response is off the cuff fresh out of vacation, my default would be to try to define what exactly a decl vs a def is in terms of the language, e.g. approximately how these would fit into the reference, then apply the names as appropriate in the compiler.

Looking at the reference we don't seem to have any consistency and seem to use all of these terms interchangeably and untangling them may be infeasible at this point:

I guess my current inclination is to just decide that "decl" is sort of a superset that includes defs and bindings, accept this change as a nice clarification where decl is more intuitive, and not worry about trying to eliminate all usages of binding at the moment, if we want to try to standardize that language we can but I think that's a bigger conversation and not necessarily high priority.

nnethercote · 2026-01-05T22:47:49Z

Ok, this seems like an improvement overall. r=me once the conflicts are fixed.

@rustbot author

rustbot · 2026-01-05T22:47:52Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Also, rename `DeclKind::Res` to `DeclKind::Def`.

…,RibDef)`

`MacroRulesBinding` -> `MacroRulesDef`

rustbot · 2026-01-06T15:24:42Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

petrochenkov · 2026-01-06T15:26:27Z

Rebased and MacroRulesDef renamed to MacroRulesDecl (#150521 (comment)).
@bors r=nnethercote

bors · 2026-01-06T15:26:29Z

📌 Commit db26d01 has been approved by nnethercote

It is now in the queue for this repository.

resolve: Rename "name bindings" to "name declarations" This was discussed previously in some name resolution specification threads on zulip. Link: [#t-compiler/help > understanding early name resolution of imports @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/understanding.20early.20name.20resolution.20of.20imports/near/545306658) The main change is that `NameBinding` is renamed to `Decl`. The `Name` part is skipped because almost everything in `rustc_resolve` is about names. So in general the naming looks more compact now (`binding: NameBinding` -> `decl: Decl`). I didn't rename *everything* including all the local variables, but did rename most of significant interfaces. Late resolution in particular uses "bindings" in slightly different meanings, I didn't touch that. Also, some interface comments are added/improved. Renaming list: - fn `define_binding_local` -> `plant_decl_into_local_module` - fn `add_macro_use_binding` -> `add_macro_use_decl` - fn `binding_description` -> `decl_description` - enum `PendingBinding` -> `PendingDecl` - field `ImportKind::Single::bindings` -> `ImportKind::Single::decls` - field `NameResolution::non_glob_binding` -> `NameResolution::non_glob_decl` - field `NameResolution::glob_binding` -> `NameResolution::glob_decl` - fn `best_binding` -> `best_decl` - fn `import` -> `new_import_decl` - fn `try_define_local` -> `try_plant_decl_into_local_module` - fn `new_ambiguity_binding` -> `new_decl_with_ambiguity` - fn `new_warn_ambiguity_binding` -> `new_decl_with_warn_ambiguity` - field `UnnecessaryQualification::binding` -> `UnnecessaryQualification::decl` - struct `MacroRulesBinding` -> `MacroRulesDef` - field `MacroRulesBinding::binding` -> `MacroRulesDef::decl` - variant `MacroRulesScope::Binding` -> `MacroRulesScope::Def` - enum `LexicalScopeBinding` -> `LateDecl` - variant `LexicalScopeBinding::Item` -> `LateDecl::Decl` - variant `LexicalScopeBinding::Res` -> `LateDecl::RibDef` - field `ModuleData::self_binding` -> `ModuleData::self_decl` - struct `NameBindingData` -> `DeclData` - type `NameBinding` -> `Decl` - enum `NameBindingKind` -> `DeclKind` - variant `NameBindingKind::Res` -> `DeclKind::Def` - field `NameBindingKind::Import::binding` -> `DeclKind::Import::source_decl` - field `PrivacyError::binding` -> `PrivacyError::decl` - field `ExternPreludeEntry::item_binding` -> `ExternPreludeEntry::item_decl` - field `ExternPreludeEntry::flag_binding` -> `ExternPreludeEntry::flag_decl` - field `Resolver::binding_parent_modules` -> `Resolver::decl_parent_modules` - field `Resolver::dummy_binding` -> `Resolver::dummy_decl` - field `Resolver::builtin_types_bindings` -> `Resolver::builtin_type_decls` - field `Resolver::builtin_attrs_bindings` -> `Resolver::builtin_attr_decls` - field `Resolver::registered_tool_bindings` -> `Resolver::registered_tool_decls` - fn `ResolverArenas::new_res_binding` -> `ResolverArenas::new_def_decl` - fn `ResolverArenas::new_pub_res_binding` -> `ResolverArenas::new_pub_def_decl` - fn `ResolverArenas::alloc_name_binding` -> `ResolverArenas::alloc_decl` - fn `ResolverArenas::alloc_macro_rules_binding` -> `ResolverArenas::alloc_macro_rules_def` - fn `set_binding_parent_module` -> `set_decl_parent_module`

Rollup of 4 pull requests Successful merges: - #150026 (Fix macro_metavar_expr_concat behavior with nested repetitions) - #150521 (resolve: Rename "name bindings" to "name declarations") - #150704 (MGCA: Const constructors support) - #150728 (Cleanup some ui tests for const-traits) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #150521 - petrochenkov:decl, r=nnethercote resolve: Rename "name bindings" to "name declarations" This was discussed previously in some name resolution specification threads on zulip. Link: [#t-compiler/help > understanding early name resolution of imports @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/understanding.20early.20name.20resolution.20of.20imports/near/545306658) The main change is that `NameBinding` is renamed to `Decl`. The `Name` part is skipped because almost everything in `rustc_resolve` is about names. So in general the naming looks more compact now (`binding: NameBinding` -> `decl: Decl`). I didn't rename *everything* including all the local variables, but did rename most of significant interfaces. Late resolution in particular uses "bindings" in slightly different meanings, I didn't touch that. Also, some interface comments are added/improved. Renaming list: - fn `define_binding_local` -> `plant_decl_into_local_module` - fn `add_macro_use_binding` -> `add_macro_use_decl` - fn `binding_description` -> `decl_description` - enum `PendingBinding` -> `PendingDecl` - field `ImportKind::Single::bindings` -> `ImportKind::Single::decls` - field `NameResolution::non_glob_binding` -> `NameResolution::non_glob_decl` - field `NameResolution::glob_binding` -> `NameResolution::glob_decl` - fn `best_binding` -> `best_decl` - fn `import` -> `new_import_decl` - fn `try_define_local` -> `try_plant_decl_into_local_module` - fn `new_ambiguity_binding` -> `new_decl_with_ambiguity` - fn `new_warn_ambiguity_binding` -> `new_decl_with_warn_ambiguity` - field `UnnecessaryQualification::binding` -> `UnnecessaryQualification::decl` - struct `MacroRulesBinding` -> `MacroRulesDef` - field `MacroRulesBinding::binding` -> `MacroRulesDef::decl` - variant `MacroRulesScope::Binding` -> `MacroRulesScope::Def` - enum `LexicalScopeBinding` -> `LateDecl` - variant `LexicalScopeBinding::Item` -> `LateDecl::Decl` - variant `LexicalScopeBinding::Res` -> `LateDecl::RibDef` - field `ModuleData::self_binding` -> `ModuleData::self_decl` - struct `NameBindingData` -> `DeclData` - type `NameBinding` -> `Decl` - enum `NameBindingKind` -> `DeclKind` - variant `NameBindingKind::Res` -> `DeclKind::Def` - field `NameBindingKind::Import::binding` -> `DeclKind::Import::source_decl` - field `PrivacyError::binding` -> `PrivacyError::decl` - field `ExternPreludeEntry::item_binding` -> `ExternPreludeEntry::item_decl` - field `ExternPreludeEntry::flag_binding` -> `ExternPreludeEntry::flag_decl` - field `Resolver::binding_parent_modules` -> `Resolver::decl_parent_modules` - field `Resolver::dummy_binding` -> `Resolver::dummy_decl` - field `Resolver::builtin_types_bindings` -> `Resolver::builtin_type_decls` - field `Resolver::builtin_attrs_bindings` -> `Resolver::builtin_attr_decls` - field `Resolver::registered_tool_bindings` -> `Resolver::registered_tool_decls` - fn `ResolverArenas::new_res_binding` -> `ResolverArenas::new_def_decl` - fn `ResolverArenas::new_pub_res_binding` -> `ResolverArenas::new_pub_def_decl` - fn `ResolverArenas::alloc_name_binding` -> `ResolverArenas::alloc_decl` - fn `ResolverArenas::alloc_macro_rules_binding` -> `ResolverArenas::alloc_macro_rules_def` - fn `set_binding_parent_module` -> `set_decl_parent_module`

rustbot assigned nnethercote Dec 30, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Dec 30, 2025

petrochenkov assigned yaahc Dec 30, 2025

nnethercote approved these changes Jan 1, 2026

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 5, 2026

petrochenkov added 6 commits January 6, 2026 18:21

resolve: Rename NameBinding(Data,Kind) to Decl(Data,Kind)

460f22c

Also, rename `DeclKind::Res` to `DeclKind::Def`.

resolve: Rename LexicalScopeBinding::(Item,Res) to `LateDecl::(Decl…

7a34af2

…,RibDef)`

resolve: MacroRulesScope::Binding -> MacroRulesScope::Def

844e085

`MacroRulesBinding` -> `MacroRulesDef`

Update some function names and fields from bindings to declarations

a67e289

Update more function names and fields from bindings to declarations

a0ea3b0

resolve: DeclKind::Import::binding -> DeclKind::Import::source_decl

db26d01

petrochenkov force-pushed the decl branch from fffe01f to db26d01 Compare January 6, 2026 15:24

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 6, 2026

matthiaskrgr mentioned this pull request Jan 6, 2026

Rollup of 4 pull requests #150729

Merged

JonathanBrouwer mentioned this pull request Jan 6, 2026

Rollup of 5 pull requests #150731

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bors merged commit e5a2b25 into rust-lang:main Jan 6, 2026
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