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expand: It's always possible to create a dummy AST fragment
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Remove a bunch of `Option`s that assumed that dummy fragment creation could fail.

The test output changed due to not performing the expansion in `fn expand_invoc` in case of the recursion limit hit.
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@petrochenkov
petrochenkov committed Jul 10, 2019
1 parent eac900a commit 374a80a
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Showing 2 changed files with 39 additions and 46 deletions.
83 changes: 39 additions & 44 deletions src/libsyntax/ext/expand.rs
View file
Expand Up @@ -158,8 +158,8 @@ ast_fragments! {
}

impl AstFragmentKind {
fn dummy(self, span: Span) -> Option<AstFragment> {
self.make_from(DummyResult::any(span))
fn dummy(self, span: Span) -> AstFragment {
self.make_from(DummyResult::any(span)).expect("couldn't create a dummy AST fragment")
}

fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
Expand Down Expand Up @@ -327,10 +327,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {

// FIXME(jseyfried): Refactor out the following logic
let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
let (invoc_fragment_kind, invoc_span) = (invoc.fragment_kind, invoc.span());
let fragment = self.expand_invoc(invoc, &ext).unwrap_or_else(|| {
invoc_fragment_kind.dummy(invoc_span).unwrap()
});
let fragment = self.expand_invoc(invoc, &ext);
self.collect_invocations(fragment, &[])
} else if let InvocationKind::Attr { attr: None, traits, item, .. } = invoc.kind {
if !item.derive_allowed() {
Expand Down Expand Up @@ -477,7 +474,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
}
}

fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> AstFragment {
if invoc.fragment_kind == AstFragmentKind::ForeignItems &&
!self.cx.ecfg.macros_in_extern() {
if let SyntaxExtensionKind::NonMacroAttr { .. } = ext.kind {} else {
Expand All @@ -487,12 +484,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
}
}

let result = match invoc.kind {
InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext)?,
InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext)?,
InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext)?,
};

if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
let info = self.cx.current_expansion.mark.expn_info().unwrap();
let suggested_limit = self.cx.ecfg.recursion_limit * 2;
Expand All @@ -507,15 +498,19 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
FatalError.raise();
}

Some(result)
match invoc.kind {
InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext),
}
}

fn expand_attr_invoc(&mut self,
invoc: Invocation,
ext: &SyntaxExtension)
-> Option<AstFragment> {
-> AstFragment {
let (attr, mut item) = match invoc.kind {
InvocationKind::Attr { attr, item, .. } => (attr?, item),
InvocationKind::Attr { attr: Some(attr), item, .. } => (attr, item),
_ => unreachable!(),
};

Expand All @@ -526,13 +521,19 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
attr::mark_used(&attr);
}
item.visit_attrs(|attrs| attrs.push(attr));
Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
invoc.fragment_kind.expect_from_annotatables(iter::once(item))
}
SyntaxExtensionKind::LegacyAttr(expander) => {
let meta = attr.parse_meta(self.cx.parse_sess)
.map_err(|mut e| { e.emit(); }).ok()?;
let item = expander.expand(self.cx, attr.span, &meta, item);
Some(invoc.fragment_kind.expect_from_annotatables(item))
match attr.parse_meta(self.cx.parse_sess) {
Ok(meta) => {
let item = expander.expand(self.cx, attr.span, &meta, item);
invoc.fragment_kind.expect_from_annotatables(item)
}
Err(mut err) => {
err.emit();
invoc.fragment_kind.dummy(attr.span)
}
}
}
SyntaxExtensionKind::Attr(expander) => {
self.gate_proc_macro_attr_item(attr.span, &item);
Expand Down Expand Up @@ -598,14 +599,10 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
);
}

fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>) {
fn gate_proc_macro_expansion(&self, span: Span, fragment: &AstFragment) {
if self.cx.ecfg.proc_macro_hygiene() {
return
}
let fragment = match fragment {
Some(fragment) => fragment,
None => return,
};

fragment.visit_with(&mut DisallowMacros {
span,
Expand Down Expand Up @@ -641,15 +638,15 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
fn expand_bang_invoc(&mut self,
invoc: Invocation,
ext: &SyntaxExtension)
-> Option<AstFragment> {
-> AstFragment {
let kind = invoc.fragment_kind;
let (mac, span) = match invoc.kind {
InvocationKind::Bang { mac, span } => (mac, span),
_ => unreachable!(),
};
let path = &mac.node.path;

let opt_expanded = match &ext.kind {
match &ext.kind {
SyntaxExtensionKind::Bang(expander) => {
self.gate_proc_macro_expansion_kind(span, kind);
let tok_result = expander.expand(self.cx, span, mac.node.stream());
Expand All @@ -659,19 +656,17 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
}
SyntaxExtensionKind::LegacyBang(expander) => {
let tok_result = expander.expand(self.cx, span, mac.node.stream());
kind.make_from(tok_result)
if let Some(result) = kind.make_from(tok_result) {
result
} else {
let msg = format!("non-{kind} macro in {kind} position: {name}",
name = path.segments[0].ident.name, kind = kind.name());
self.cx.span_err(path.span, &msg);
self.cx.trace_macros_diag();
kind.dummy(span)
}
}
_ => unreachable!()
};

if opt_expanded.is_some() {
opt_expanded
} else {
let msg = format!("non-{kind} macro in {kind} position: {name}",
name = path.segments[0].ident.name, kind = kind.name());
self.cx.span_err(path.span, &msg);
self.cx.trace_macros_diag();
kind.dummy(span)
}
}

Expand Down Expand Up @@ -703,7 +698,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
fn expand_derive_invoc(&mut self,
invoc: Invocation,
ext: &SyntaxExtension)
-> Option<AstFragment> {
-> AstFragment {
let (path, item) = match invoc.kind {
InvocationKind::Derive { path, item, item_with_markers } => match ext.kind {
SyntaxExtensionKind::LegacyDerive(..) => (path, item_with_markers),
Expand All @@ -712,7 +707,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
_ => unreachable!(),
};
if !item.derive_allowed() {
return None;
return invoc.fragment_kind.dummy(path.span);
}

match &ext.kind {
Expand All @@ -721,7 +716,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
let meta = ast::MetaItem { node: ast::MetaItemKind::Word, span: path.span, path };
let span = meta.span.with_ctxt(self.cx.backtrace());
let items = expander.expand(self.cx, span, &meta, item);
Some(invoc.fragment_kind.expect_from_annotatables(items))
invoc.fragment_kind.expect_from_annotatables(items)
}
_ => unreachable!()
}
Expand All @@ -732,12 +727,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
kind: AstFragmentKind,
path: &Path,
span: Span)
-> Option<AstFragment> {
-> AstFragment {
let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
match parser.parse_ast_fragment(kind, false) {
Ok(fragment) => {
parser.ensure_complete_parse(path, kind.name(), span);
Some(fragment)
fragment
}
Err(mut err) => {
err.set_span(span);
Expand Down
2 changes: 0 additions & 2 deletions src/test/ui/macros/trace_faulty_macros.stderr
View file
Expand Up @@ -45,8 +45,6 @@ LL | my_recursive_macro!();
= note: to `my_recursive_macro ! ( ) ;`
= note: expanding `my_recursive_macro! { }`
= note: to `my_recursive_macro ! ( ) ;`
= note: expanding `my_recursive_macro! { }`
= note: to `my_recursive_macro ! ( ) ;`

error: aborting due to 2 previous errors

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