Implement Pandoc Markdown concise link extension

This implements nim-lang#20127.
Besides reference to headings we also support doing references
to Nim symbols inside Nim modules.

Markdown:
```
Some heading
------------

Ref. [Some heading].
```

Nim:
```
proc someFunction*() ...

... ## Ref. [someFunction]
```

This is substitution for RST syntax like `` `target`_ ``.
All 3 syntax variants of extension from Pandoc Markdown are supported:
`[target]`, `[target][]`, `[description][target]`.

This PR also fixes clashes in existing files, particularly
conflicts with RST footnote feature, which does not work with
this PR (but there is a plan to adopt a popular [Markdown footnote
extension](https://pandoc.org/MANUAL.html#footnotes) to make footnotes work).

Also the PR fixes a bug that Markdown links did not work when `[...]`
section had a line break.

The implementation is straightforward since link resolution did not
change w.r.t. RST implementation, it's almost only about new syntax
addition. The only essential difference is a possibility to add a custom
link description: form `[description][target]` which does not have an
RST equivalent.

doc/basicopt.txt

@@ -4,7 +4,7 @@
 
 Command:
   //compile, c              compile project with default code generator (C)
-  //r                       compile to $nimcache/projname, run with [arguments]
+  //r                       compile to $nimcache/projname, run with `arguments`
                             using backend specified by `--backend` (default: c)
   //doc                     generate the documentation for inputfile for
                             backend specified by `--backend` (default: c)

doc/contributing.md

@@ -336,7 +336,7 @@ To avoid accidental highlighting follow this rule in ``*.nim`` files:
 
 .. Note:: ``*.rst`` files have ``:literal:`` as their default role.
           So for them the rule above is only applicable if the ``:nim:`` role
-          is set up manually as the default [*]_::
+          is set up manually as the default \[*]::
 
             .. role:: nim(code)
                :language: nim
@@ -345,7 +345,7 @@ To avoid accidental highlighting follow this rule in ``*.nim`` files:
           The first 2 lines are for other RST implementations,
           including Github one.
 
-          .. [*] this is fulfilled when ``doc/rstcommon.rst`` is included.
+          \[*] this is fulfilled when ``doc/rstcommon.rst`` is included.
 
 Best practices
 ==============
@@ -431,7 +431,7 @@ including prepending location info, writing to log files, etc.).
   ```
 
 .. _use_Option:
-[Ongoing debate] Consider using Option instead of return bool + var argument,
+(Ongoing debate) Consider using Option instead of return bool + var argument,
 unless stack allocation is needed (e.g. for efficiency).
 
   ```nim

doc/docgen.md

@@ -245,9 +245,9 @@ underscore `_` to a *link text*.
 Link text is either one word or a group of words enclosed by backticks `\``
 (for a one word case backticks are usually omitted).
 Link text will be displayed *as is* while *link target* will be set to
-the anchor [*]_ of Nim symbol that corresponds to link text.
+the anchor \[*] of Nim symbol that corresponds to link text.
 
-.. [*] anchors' format is described in `HTML anchor generation`_ section below.
+[*] anchors' format is described in `HTML anchor generation`_ section below.
 
 If you have a constant:
 

doc/idetools.md

@@ -239,7 +239,7 @@ symbol for which idetools returns valid output.
 skConst
 -------
 
-| **Third column**: module + [n scope nesting] + const name.
+| **Third column**: module + \[n scope nesting] + const name.
 | **Fourth column**: the type of the const value.
 | **Docstring**: always the empty string.
 
@@ -254,7 +254,7 @@ skConst
 skEnumField
 -----------
 
-| **Third column**: module + [n scope nesting] + enum type + enum field name.
+| **Third column**: module + \[n scope nesting] + enum type + enum field name.
 | **Fourth column**: enum type grouping other enum fields.
 | **Docstring**: always the empty string.
 
@@ -269,7 +269,7 @@ skEnumField
 skForVar
 --------
 
-| **Third column**: module + [n scope nesting] + var name.
+| **Third column**: module + \[n scope nesting] + var name.
 | **Fourth column**: type of the var.
 | **Docstring**: always the empty string.
 
@@ -291,7 +291,7 @@ defined, since at that point in the file the parser hasn't processed
 the full line yet. The signature will be returned complete in
 posterior instances of the iterator.
 
-| **Third column**: module + [n scope nesting] + iterator name.
+| **Third column**: module + \[n scope nesting] + iterator name.
 | **Fourth column**: signature of the iterator including return type.
 | **Docstring**: docstring if available.
 
@@ -308,7 +308,7 @@ posterior instances of the iterator.
 skLabel
 -------
 
-| **Third column**: module + [n scope nesting] + name.
+| **Third column**: module + \[n scope nesting] + name.
 | **Fourth column**: always the empty string.
 | **Docstring**: always the empty string.
 
@@ -325,7 +325,7 @@ skLabel
 skLet
 -----
 
-| **Third column**: module + [n scope nesting] + let name.
+| **Third column**: module + \[n scope nesting] + let name.
 | **Fourth column**: the type of the let variable.
 | **Docstring**: always the empty string.
 
@@ -346,7 +346,7 @@ defined, since at that point in the file the parser hasn't processed
 the full line yet. The signature will be returned complete in
 posterior instances of the macro.
 
-| **Third column**: module + [n scope nesting] + macro name.
+| **Third column**: module + \[n scope nesting] + macro name.
 | **Fourth column**: signature of the macro including return type.
 | **Docstring**: docstring if available.
 
@@ -384,7 +384,7 @@ Note that at the moment the word `proc` is returned for the
 signature of the found method instead of the expected `method`.
 This may change in the future.
 
-| **Third column**: module + [n scope nesting] + method name.
+| **Third column**: module + \[n scope nesting] + method name.
 | **Fourth column**: signature of the method including return type.
 | **Docstring**: docstring if available.
 
@@ -402,7 +402,7 @@ This may change in the future.
 skParam
 -------
 
-| **Third column**: module + [n scope nesting] + param name.
+| **Third column**: module + \[n scope nesting] + param name.
 | **Fourth column**: the type of the parameter.
 | **Docstring**: always the empty string.
 
@@ -427,7 +427,7 @@ While at the language level a proc is differentiated from others
 by the parameters and return value, the signature of the proc
 returned by idetools returns also the pragmas for the proc.
 
-| **Third column**: module + [n scope nesting] + proc name.
+| **Third column**: module + \[n scope nesting] + proc name.
 | **Fourth column**: signature of the proc including return type.
 | **Docstring**: docstring if available.
 
@@ -446,7 +446,7 @@ returned by idetools returns also the pragmas for the proc.
 skResult
 --------
 
-| **Third column**: module + [n scope nesting] + result.
+| **Third column**: module + \[n scope nesting] + result.
 | **Fourth column**: the type of the result.
 | **Docstring**: always the empty string.
 
@@ -467,7 +467,7 @@ defined, since at that point in the file the parser hasn't processed
 the full line yet. The signature will be returned complete in
 posterior instances of the template.
 
-| **Third column**: module + [n scope nesting] + template name.
+| **Third column**: module + \[n scope nesting] + template name.
 | **Fourth column**: signature of the template including return type.
 | **Docstring**: docstring if available.
 
@@ -496,7 +496,7 @@ posterior instances of the template.
 skType
 ------
 
-| **Third column**: module + [n scope nesting] + type name.
+| **Third column**: module + \[n scope nesting] + type name.
 | **Fourth column**: the type.
 | **Docstring**: always the empty string.
 
@@ -512,7 +512,7 @@ skType
 skVar
 -----
 
-| **Third column**: module + [n scope nesting] + var name.
+| **Third column**: module + \[n scope nesting] + var name.
 | **Fourth column**: the type of the var.
 | **Docstring**: always the empty string.
 

doc/intern.md

@@ -328,7 +328,7 @@ Coding Guidelines
 * Max line length is 100 characters.
 * Provide spaces around binary operators if that enhances readability.
 * Use a space after a colon, but not before it.
-* [deprecated] Start types with a capital `T`, unless they are
+* (deprecated) Start types with a capital `T`, unless they are
   pointers/references which start with `P`.
 * Prefer `import package`:nim: over `from package import symbol`:nim:.
 

doc/manual.md

@@ -2862,11 +2862,11 @@ ref or pointer type             nil
 procedural type                 nil
 sequence                        `@[]`
 string                          `""`
-tuple[x: A, y: B, ...]          (default(A), default(B), ...)
+`tuple[x: A, y: B, ...]`        (default(A), default(B), ...)
                                 (analogous for objects)
-array[0..., T]                  [default(T), ...]
-range[T]                        default(T); this may be out of the valid range
-T = enum                        cast[T]\(0); this may be an invalid value
+`array[0..., T]`                `[default(T), ...]`
+`range[T]`                      default(T); this may be out of the valid range
+T = enum                        `cast[T](0)`; this may be an invalid value
 ============================    ==============================================
 
 

lib/core/macros.nim

@@ -182,7 +182,7 @@ template `^^`(n: NimNode, i: untyped): untyped =
 
 proc `[]`*[T, U: Ordinal](n: NimNode, x: HSlice[T, U]): seq[NimNode] =
   ## Slice operation for NimNode.
-  ## Returns a seq of child of `n` who inclusive range [n[x.a], n[x.b]].
+  ## Returns a seq of child of `n` who inclusive range `[n[x.a], n[x.b]]`.
   let xa = n ^^ x.a
   let L = (n ^^ x.b) - xa + 1
   result = newSeq[NimNode](L)

lib/impure/db_mysql.nim

@@ -180,7 +180,7 @@ iterator fastRows*(db: DbConn, query: SqlQuery,
   ## if you require **ALL** the rows.
   ##
   ## Breaking the fastRows() iterator during a loop will cause the next
-  ## database query to raise an [EDb] exception `Commands out of sync`.
+  ## database query to raise an `EDb` exception `Commands out of sync`.
   rawExec(db, query, args)
   var sqlres = mysql.useResult(PMySQL db)
   if sqlres != nil:
@@ -203,7 +203,7 @@ iterator instantRows*(db: DbConn, query: SqlQuery,
                       args: varargs[string, `$`]): InstantRow
                       {.tags: [ReadDbEffect].} =
   ## Same as fastRows but returns a handle that can be used to get column text
-  ## on demand using []. Returned handle is valid only within the iterator body.
+  ## on demand using `[]`. Returned handle is valid only within the iterator body.
   rawExec(db, query, args)
   var sqlres = mysql.useResult(PMySQL db)
   if sqlres != nil:
@@ -283,7 +283,7 @@ proc setColumnInfo(columns: var DbColumns; res: PRES; L: int) =
 iterator instantRows*(db: DbConn; columns: var DbColumns; query: SqlQuery;
                       args: varargs[string, `$`]): InstantRow =
   ## Same as fastRows but returns a handle that can be used to get column text
-  ## on demand using []. Returned handle is valid only within the iterator body.
+  ## on demand using `[]`. Returned handle is valid only within the iterator body.
   rawExec(db, query, args)
   var sqlres = mysql.useResult(PMySQL db)
   if sqlres != nil:

lib/impure/db_odbc.nim

@@ -168,7 +168,7 @@ proc dbError*(db: var DbConn) {.
     raise e
 
 proc sqlCheck(db: var DbConn, resVal: TSqlSmallInt) {.raises: [DbError]} =
-  ## Wrapper that raises [EDb] if `resVal` is neither SQL_SUCCESS or SQL_NO_DATA
+  ## Wrapper that raises `EDb` if `resVal` is neither SQL_SUCCESS or SQL_NO_DATA
   if resVal notIn [SQL_SUCCESS, SQL_NO_DATA]: dbError(db)
 
 proc sqlGetDBMS(db: var DbConn): string {.
@@ -304,7 +304,7 @@ iterator instantRows*(db: var DbConn, query: SqlQuery,
                       args: varargs[string, `$`]): InstantRow
                 {.tags: [ReadDbEffect, WriteDbEffect].} =
   ## Same as fastRows but returns a handle that can be used to get column text
-  ## on demand using []. Returned handle is valid only within the iterator body.
+  ## on demand using `[]`. Returned handle is valid only within the iterator body.
   var
     rowRes: Row = @[]
     sz: TSqlLen = 0

lib/impure/db_postgres.nim

@@ -271,15 +271,15 @@ iterator instantRows*(db: DbConn, query: SqlQuery,
                       args: varargs[string, `$`]): InstantRow
                       {.tags: [ReadDbEffect].} =
   ## same as fastRows but returns a handle that can be used to get column text
-  ## on demand using []. Returned handle is valid only within iterator body.
+  ## on demand using `[]`. Returned handle is valid only within iterator body.
   setupSingeRowQuery(db, query, args)
   fetchinstantRows(db)
 
 iterator instantRows*(db: DbConn, stmtName: SqlPrepared,
                       args: varargs[string, `$`]): InstantRow
                       {.tags: [ReadDbEffect].} =
   ## same as fastRows but returns a handle that can be used to get column text
-  ## on demand using []. Returned handle is valid only within iterator body.
+  ## on demand using `[]`. Returned handle is valid only within iterator body.
   setupSingeRowQuery(db, stmtName, args)
   fetchinstantRows(db)
 

lib/packages/docutils/dochelpers.nim

@@ -82,7 +82,7 @@ proc toLangSymbol*(linkText: PRstNode): LangSymbol =
   ##
   ## This proc should be kept in sync with the `renderTypes` proc from
   ## ``compiler/typesrenderer.nim``.
-  assert linkText.kind in {rnRef, rnInner}
+  assert linkText.kind in {rnRstRef, rnInner}
 
   const NimDefs = ["proc", "func", "macro", "method", "iterator",
                    "template", "converter", "const", "type", "var",