.markdown-body {
    font-size: 14px;
    line-height: 1.6;
    overflow: hidden;
    color: #CCCAC2;
}
.markdown-body>*:first-child {
    margin-top: 0 !important;
}
.markdown-body>*:last-child {
    margin-bottom: 0 !important;
}
.markdown-body a.absent {
    color: #FF6666;
}
.markdown-body a.anchor {
    display: block;
    padding-left: 30px;
    margin-left: -30px;
    cursor: pointer;
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
}
.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4, .markdown-body h5, .markdown-body h6 {
    margin: 20px 0 10px;
    padding: 0;
    font-weight: bold;
    -webkit-font-smoothing: antialiased;
    cursor: text;
    position: relative;
    color: #CCCAC2;
}
.markdown-body h1 .mini-icon-link, .markdown-body h2 .mini-icon-link, .markdown-body h3 .mini-icon-link, .markdown-body h4 .mini-icon-link, .markdown-body h5 .mini-icon-link, .markdown-body h6 .mini-icon-link {
    display: none;
    color: #CCCAC2;
}
.markdown-body h1:hover a.anchor, .markdown-body h2:hover a.anchor, .markdown-body h3:hover a.anchor, .markdown-body h4:hover a.anchor, .markdown-body h5:hover a.anchor, .markdown-body h6:hover a.anchor {
    text-decoration: none;
    line-height: 1;
    padding-left: 0;
    margin-left: -22px;
    top: 15%;
}
.markdown-body h1:hover a.anchor .mini-icon-link, .markdown-body h2:hover a.anchor .mini-icon-link, .markdown-body h3:hover a.anchor .mini-icon-link, .markdown-body h4:hover a.anchor .mini-icon-link, .markdown-body h5:hover a.anchor .mini-icon-link, .markdown-body h6:hover a.anchor .mini-icon-link {
    display: inline-block;
}
div#cgit .markdown-body h1 a.toclink, div#cgit .markdown-body h2 a.toclink, div#cgit .markdown-body h3 a.toclink, div#cgit .markdown-body h4 a.toclink, div#cgit .markdown-body h5 a.toclink, div#cgit .markdown-body h6 a.toclink {
    color: #CCCAC2;
}
.markdown-body h1 tt, .markdown-body h1 code, .markdown-body h2 tt, .markdown-body h2 code, .markdown-body h3 tt, .markdown-body h3 code, .markdown-body h4 tt, .markdown-body h4 code, .markdown-body h5 tt, .markdown-body h5 code, .markdown-body h6 tt, .markdown-body h6 code {
    font-size: inherit;
}
.markdown-body h1 {
    font-size: 28px;
    color: #CCCAC2;
}
.markdown-body h2 {
    font-size: 24px;
    border-bottom: 1px solid #8A9199;
    color: #CCCAC2;
}
.markdown-body h3 {
    font-size: 18px;
    color: #CCCAC2;
}
.markdown-body h4 {
    font-size: 16px;
    color: #CCCAC2;
}
.markdown-body h5 {
    font-size: 14px;
    color: #CCCAC2;
}
.markdown-body h6 {
    color: #CCCAC2;
    font-size: 14px;
}
.markdown-body p, .markdown-body blockquote, .markdown-body ul, .markdown-body ol, .markdown-body dl, .markdown-body table, .markdown-body pre {
    margin: 15px 0;
}
.markdown-body hr {
    border: 2px solid #8A9199;
}
.markdown-body>h2:first-child, .markdown-body>h1:first-child, .markdown-body>h1:first-child+h2, .markdown-body>h3:first-child, .markdown-body>h4:first-child, .markdown-body>h5:first-child, .markdown-body>h6:first-child {
    margin-top: 0;
    padding-top: 0;
}
.markdown-body a:first-child h1, .markdown-body a:first-child h2, .markdown-body a:first-child h3, .markdown-body a:first-child h4, .markdown-body a:first-child h5, .markdown-body a:first-child h6 {
    margin-top: 0;
    padding-top: 0;
}
.markdown-body h1+p, .markdown-body h2+p, .markdown-body h3+p, .markdown-body h4+p, .markdown-body h5+p, .markdown-body h6+p {
    margin-top: 0;
}
.markdown-body li p.first {
    display: inline-block;
}
.markdown-body ul, .markdown-body ol {
    padding-left: 30px;
}
.markdown-body ul.no-list, .markdown-body ol.no-list {
    list-style-type: none;
    padding: 0;
}
.markdown-body ul li>:first-child, .markdown-body ul li ul:first-of-type, .markdown-body ul li ol:first-of-type, .markdown-body ol li>:first-child, .markdown-body ol li ul:first-of-type, .markdown-body ol li ol:first-of-type {
    margin-top: 0px;
}
.markdown-body ul li p:last-of-type, .markdown-body ol li p:last-of-type {
    margin-bottom: 0;
}
.markdown-body ul ul, .markdown-body ul ol, .markdown-body ol ol, .markdown-body ol ul {
    margin-bottom: 0;
}
.markdown-body dl {
    padding: 0;
}
.markdown-body dl dt {
    font-size: 14px;
    font-weight: bold;
    font-style: italic;
    padding: 0;
    margin: 15px 0 5px;
}
.markdown-body dl dt:first-child {
    padding: 0;
}
.markdown-body dl dt>:first-child {
    margin-top: 0px;
}
.markdown-body dl dt>:last-child {
    margin-bottom: 0px;
}
.markdown-body dl dd {
    margin: 0 0 15px;
    padding: 0 15px;
}
.markdown-body dl dd>:first-child {
    margin-top: 0px;
}
.markdown-body dl dd>:last-child {
    margin-bottom: 0px;
}
.markdown-body blockquote {
    border-left: 4px solid #FFAD66;
    padding: 0 15px;
    color: #B8CFE6;
}
.markdown-body blockquote>:first-child {
    margin-top: 0px;
}
.markdown-body blockquote>:last-child {
    margin-bottom: 0px;
}
.markdown-body table th {
    font-weight: bold;
}
.markdown-body table th, .markdown-body table td {
    border: 1px solid #8A9199;
    padding: 6px 13px;
}
.markdown-body table tr {
    border-top: 1px solid #8A9199;
    background-color: #242936;
}
.markdown-body table tr:nth-child(2n) {
    background-color: #1A1F29;
}
.markdown-body img {
    max-width: 100%;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
.markdown-body span.frame {
    display: block;
    overflow: hidden;
}
.markdown-body span.frame>span {
    border: 1px solid #8A9199;
    display: block;
    float: left;
    overflow: hidden;
    margin: 13px 0 0;
    padding: 7px;
    width: auto;
}
.markdown-body span.frame span img {
    display: block;
    float: left;
}
.markdown-body span.frame span span {
    clear: both;
    color: #CCCAC2;
    display: block;
    padding: 5px 0 0;
}
.markdown-body span.align-center {
    display: block;
    overflow: hidden;
    clear: both;
}
.markdown-body span.align-center>span {
    display: block;
    overflow: hidden;
    margin: 13px auto 0;
    text-align: center;
}
.markdown-body span.align-center span img {
    margin: 0 auto;
    text-align: center;
}
.markdown-body span.align-right {
    display: block;
    overflow: hidden;
    clear: both;
}
.markdown-body span.align-right>span {
    display: block;
    overflow: hidden;
    margin: 13px 0 0;
    text-align: right;
}
.markdown-body span.align-right span img {
    margin: 0;
    text-align: right;
}
.markdown-body span.float-left {
    display: block;
    margin-right: 13px;
    overflow: hidden;
    float: left;
}
.markdown-body span.float-left span {
    margin: 13px 0 0;
}
.markdown-body span.float-right {
    display: block;
    margin-left: 13px;
    overflow: hidden;
    float: right;
}
.markdown-body span.float-right>span {
    display: block;
    overflow: hidden;
    margin: 13px auto 0;
    text-align: right;
}
.markdown-body code, .markdown-body tt {
    margin: 0 2px;
    padding: 0px 5px;
    border: 1px solid #8A9199;
    background-color: #282E3B;
    border-radius: 3px;
    color: #CCCAC2;
}
.markdown-body code {
    white-space: nowrap;
}
.markdown-body pre>code {
    margin: 0;
    padding: 0;
    white-space: pre;
    border: none;
    background: transparent;
}
.markdown-body .highlight pre, .markdown-body pre {
    background-color: #282E3B;
    border: 1px solid #8A9199;
    font-size: 13px;
    line-height: 19px;
    overflow: auto;
    padding: 6px 10px;
    border-radius: 3px;
}
.markdown-body pre code, .markdown-body pre tt {
    margin: 0;
    padding: 0;
    background-color: transparent;
    border: none;
}
pre { line-height: 125%; }
td.linenos .normal { color: #8a919966; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: #8a919966; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #363C48 }
.highlight .c { color: #6E7C8E } /* Comment */
.highlight .err { color: #FF6666 } /* Error */
.highlight .g { color: #CCCAC2 } /* Generic */
.highlight .k { color: #FFAD66 } /* Keyword */
.highlight .o { color: #F29E74 } /* Operator */
.highlight .ch { color: #6E7C8E } /* Comment.Hashbang */
.highlight .cm { color: #6E7C8E; font-style: italic } /* Comment.Multiline */
.highlight .cp { color: #FFAD66 } /* Comment.Preproc */
.highlight .cpf { color: #D5FF80 } /* Comment.PreprocFile */
.highlight .c1 { color: #6E7C8E; font-style: italic } /* Comment.Single */
.highlight .cs { color: #6E7C8E } /* Comment.Special */
.highlight .gd { color: #F27983 } /* Generic.Deleted */
.highlight .ge { color: #FFD173; font-style: italic } /* Generic.Emph */
.highlight .gr { color: #FF6666 } /* Generic.Error */
.highlight .gh { color: #FFD173; font-weight: bold } /* Generic.Heading */
.highlight .gi { color: #87D96C } /* Generic.Inserted */
.highlight .go { color: #D5FF80 } /* Generic.Output */
.highlight .gp { color: #F29E74 } /* Generic.Prompt */
.highlight .gs { color: #FFD173; font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #CCCAC2 } /* Generic.Subheading */
.highlight .gt { color: #FF6666 } /* Generic.Traceback */
.highlight .kc { color: #DFBFFF } /* Keyword.Constant */
.highlight .kd { color: #FFCC66 } /* Keyword.Declaration */
.highlight .kn { color: #FFAD66 } /* Keyword.Namespace */
.highlight .kp { color: #FFAD66 } /* Keyword.Pseudo */
.highlight .kr { color: #FFAD66 } /* Keyword.Reserved */
.highlight .kt { color: #73D0FF } /* Keyword.Type */
.highlight .m { color: #DFBFFF } /* Literal.Number */
.highlight .s { color: #D5FF80 } /* Literal.String */
.highlight .na { color: #FFD173 } /* Name.Attribute */
.highlight .nb { color: #F28779 } /* Name.Builtin */
.highlight .nc { color: #5CCFE6 } /* Name.Class */
.highlight .no { color: #DFBFFF } /* Name.Constant */
.highlight .nd { color: #FFDFB3 } /* Name.Decorator */
.highlight .nf { color: #FFD173 } /* Name.Function */
.highlight .nt { color: #5CCFE6 } /* Name.Tag */
.highlight .ow { color: #F29E74 } /* Operator.Word */
.highlight .w { color: #CCCAC2 } /* Text.Whitespace */
.highlight .mb { color: #DFBFFF } /* Literal.Number.Bin */
.highlight .mf { color: #DFBFFF } /* Literal.Number.Float */
.highlight .mh { color: #DFBFFF } /* Literal.Number.Hex */
.highlight .mi { color: #DFBFFF } /* Literal.Number.Integer */
.highlight .mo { color: #DFBFFF } /* Literal.Number.Oct */
.highlight .sa { color: #D5FF80 } /* Literal.String.Affix */
.highlight .sb { color: #F29E74 } /* Literal.String.Backtick */
.highlight .sc { color: #D5FF80 } /* Literal.String.Char */
.highlight .dl { color: #D5FF80 } /* Literal.String.Delimiter */
.highlight .sd { color: #95E6CB; font-style: italic } /* Literal.String.Doc */
.highlight .s2 { color: #D5FF80 } /* Literal.String.Double */
.highlight .se { color: #D5FF80 } /* Literal.String.Escape */
.highlight .sh { color: #D5FF80 } /* Literal.String.Heredoc */
.highlight .si { color: #D5FF80 } /* Literal.String.Interpol */
.highlight .sx { color: #D5FF80 } /* Literal.String.Other */
.highlight .sr { color: #95E6CB } /* Literal.String.Regex */
.highlight .s1 { color: #D5FF80 } /* Literal.String.Single */
.highlight .ss { color: #D5FF80 } /* Literal.String.Symbol */
.highlight .bp { color: #F28779 } /* Name.Builtin.Pseudo */
.highlight .fm { color: #FFD173 } /* Name.Function.Magic */
.highlight .vi { color: #FFCC66 } /* Name.Variable.Instance */
.highlight .vm { color: #5CCFE6; font-style: italic } /* Name.Variable.Magic */
.highlight .il { color: #DFBFFF } /* Literal.Number.Integer.Long */
   

name: Feature request
about: Suggest a new feature or improvement
title: ''
labels: C-enhancement
assignees: ''



Describe your feature request
			

		
		
	

<-- other_range
        //         3-5 5-6 6-7                     <-- ranges we replace (len = 7-3 = 4)
        //         ^^^^^^^^^^^ ^^^^^^^^^^
        //           remove       shift
        //   2   3   5   9                         <-- offsets we insert
        // 0-2 2-3 3-5 5-9                         <-- ranges we insert (other_size = 9-0 = 9)
        // ------------------------------------
        //   1   3
        // 0-1 1-3                                 <-- these remain intact
        //           5   6   8   12
        //         3-5 5-6 6-8 8-12                <-- we shift these by other_range.start() and insert them
        //                             15    16
        //                          12-15 15-16    <-- we shift these by other_size-other_range.len() = 9-4 = 5
        // ------------------------------------
        //   1   3   5   6   8   12    15    16    <-- final offsets we store
        // 0-1 1-3 3-5 5-6 6-8 8-12 12-15 15-16    <-- final ranges

        self.spans.retain_mut(|(offset, _)| {
            if other_range.start() < *offset && *offset <= other_range.end() {
                false
            } else {
                if *offset > other_range.end() {
                    *offset += other_size;
                    *offset -= other_range.len();
                }
                true
            }
        });

        self.spans
            .extend(other.spans.iter().map(|&(offset, span)| (offset + other_range.start(), span)));

        self.spans.sort_unstable_by_key(|&(offset, _)| offset);

        // Matched arm info is no longer correct once we have multiple macros.
        self.matched_arm = None;
    }
}

#[cfg(not(no_salsa_async_drops))]
impl Drop for SpanMap {
    fn drop(&mut self) {
        let spans = std::mem::take(&mut self.spans);
        static SPAN_MAP_DROP_THREAD: std::sync::OnceLock<
            std::sync::mpsc::Sender<Vec<(TextSize, Span)>>,
        > = std::sync::OnceLock::new();

        SPAN_MAP_DROP_THREAD
            .get_or_init(|| {
                let (sender, receiver) = std::sync::mpsc::channel::<Vec<(TextSize, Span)>>();
                std::thread::Builder::new()
                    .name("SpanMapDropper".to_owned())
                    .spawn(move || {
                        loop {
                            // block on a receive
                            _ = receiver.recv();
                            // then drain the entire channel
                            while receiver.try_recv().is_ok() {}
                            // and sleep for a bit
                            std::thread::sleep(std::time::Duration::from_millis(100));
                        }
                        // why do this over just a `receiver.iter().for_each(drop)`? To reduce contention on the channel lock.
                        // otherwise this thread will constantly wake up and sleep again.
                    })
                    .unwrap();
                sender
            })
            .send(spans)
            .unwrap();
    }
}

#[derive(PartialEq, Eq, Hash, Debug)]
pub struct RealSpanMap {
    file_id: EditionedFileId,
    /// Invariant: Sorted vec over TextSize
    // FIXME: SortedVec<(TextSize, ErasedFileAstId)>?
    pairs: Box<[(TextSize, ErasedFileAstId)]>,
    end: TextSize,
}

impl fmt::Display for RealSpanMap {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "RealSpanMap({:?}):", self.file_id)?;
        for span in self.pairs.iter() {
            writeln!(f, "{}: {:#?}", u32::from(span.0), span.1)?;
        }
        Ok(())
    }
}

impl RealSpanMap {
    /// Creates a real file span map that returns absolute ranges (relative ranges to the root ast id).
    pub fn absolute(file_id: EditionedFileId) -> Self {
        RealSpanMap {
            file_id,
            pairs: Box::from([(TextSize::new(0), ROOT_ERASED_FILE_AST_ID)]),
            end: TextSize::new(!0),
        }
    }

    pub fn from_file(
        file_id: EditionedFileId,
        pairs: Box<[(TextSize, ErasedFileAstId)]>,
        end: TextSize,
    ) -> Self {
        Self { file_id, pairs, end }
    }

    pub fn span_for_range(&self, range: TextRange) -> Span {
        assert!(
            range.end() <= self.end,
            "range {range:?} goes beyond the end of the file {:?}",
            self.end
        );
        let start = range.start();
        let idx = self
            .pairs
            .binary_search_by(|&(it, _)| it.cmp(&start).then(std::cmp::Ordering::Less))
            .unwrap_err();
        let (offset, ast_id) = self.pairs[idx - 1];
        Span {
            range: range - offset,
            anchor: SpanAnchor { file_id: self.file_id, ast_id },
            ctx: SyntaxContext::root(self.file_id.edition()),
        }
    }
}