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Diffstat (limited to 'crates/hir-expand/src/builtin/fn_macro.rs')
| -rw-r--r-- | crates/hir-expand/src/builtin/fn_macro.rs | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/crates/hir-expand/src/builtin/fn_macro.rs b/crates/hir-expand/src/builtin/fn_macro.rs index 60fbc66065..4a9af01091 100644 --- a/crates/hir-expand/src/builtin/fn_macro.rs +++ b/crates/hir-expand/src/builtin/fn_macro.rs @@ -127,6 +127,7 @@ register_builtin! { (asm, Asm) => asm_expand, (global_asm, GlobalAsm) => global_asm_expand, (naked_asm, NakedAsm) => naked_asm_expand, + (cfg_select, CfgSelect) => cfg_select_expand, (cfg, Cfg) => cfg_expand, (core_panic, CorePanic) => panic_expand, (std_panic, StdPanic) => panic_expand, @@ -355,6 +356,71 @@ fn naked_asm_expand( ExpandResult::ok(expanded) } +fn cfg_select_expand( + db: &dyn ExpandDatabase, + id: MacroCallId, + tt: &tt::TopSubtree, + span: Span, +) -> ExpandResult<tt::TopSubtree> { + let loc = db.lookup_intern_macro_call(id); + let cfg_options = loc.krate.cfg_options(db); + + let mut iter = tt.iter(); + let mut expand_to = None; + while let Some(next) = iter.peek() { + let active = if let tt::TtElement::Leaf(tt::Leaf::Ident(ident)) = next + && ident.sym == sym::underscore + { + iter.next(); + true + } else { + cfg_options.check(&CfgExpr::parse_from_iter(&mut iter)) != Some(false) + }; + match iter.expect_glued_punct() { + Ok(it) if it.len() == 2 && it[0].char == '=' && it[1].char == '>' => {} + _ => { + let err_span = iter.peek().map(|it| it.first_span()).unwrap_or(span); + return ExpandResult::new( + tt::TopSubtree::empty(tt::DelimSpan::from_single(span)), + ExpandError::other(err_span, "expected `=>` after cfg expression"), + ); + } + } + let expand_to_if_active = match iter.next() { + Some(tt::TtElement::Subtree(_, tt)) => tt.remaining(), + _ => { + let err_span = iter.peek().map(|it| it.first_span()).unwrap_or(span); + return ExpandResult::new( + tt::TopSubtree::empty(tt::DelimSpan::from_single(span)), + ExpandError::other(err_span, "expected a token tree after `=>`"), + ); + } + }; + + if expand_to.is_none() && active { + expand_to = Some(expand_to_if_active); + } + } + match expand_to { + Some(expand_to) => { + let mut builder = tt::TopSubtreeBuilder::new(tt::Delimiter { + kind: tt::DelimiterKind::Invisible, + open: span, + close: span, + }); + builder.extend_with_tt(expand_to); + ExpandResult::ok(builder.build()) + } + None => ExpandResult::new( + tt::TopSubtree::empty(tt::DelimSpan::from_single(span)), + ExpandError::other( + span, + "none of the predicates in this `cfg_select` evaluated to true", + ), + ), + } +} + fn cfg_expand( db: &dyn ExpandDatabase, id: MacroCallId, |