Add F# code snippets (Ctrl+K,Ctrl+X / Ctrl+K,Ctrl+S) - #20521
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Insert Snippet and Surround With have had nothing to offer in an F# file: the Code Snippets Manager has no F# entry and this repository contains no `.snippet` file at all. Adds 40 snippets covering the part of the C# set that has an F# analogue - declarations, members, control flow, computation expressions - together with the registration and packaging that lets Visual Studio find them. `Languages\CodeExpansions\FSharp` is written into the pkgdef rather than produced by `ProvideLanguageCodeExpansionAttribute`, which does not expose the `Package` value that `DisplayName` resolves against; C#, VB, XAML, XML and TypeScript all register by hand for the same reason. Only 1033 is registered, and outright rather than as `%LCID%`: registering both would enumerate every snippet twice on an English VS. The shipped directory is `Snippets\1033\FSharp`, not `Visual F#`, because a '#' in a VSIX part URI reads as a URI fragment and the packaging step refuses it. `SnippetsIndex.xml` supplies the folder name the Code Snippets Manager shows. Bodies are authored at column 0 with 4-space relative indentation - absolute indentation is applied at insertion time - and every snippet carries an explicit `$end$`, which is what lets the expansion client avoid reading the snippet XML back out of the live session. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Insert Snippet (Ctrl+K,Ctrl+X), Surround With (Ctrl+K,Ctrl+S), Tab expansion of a snippet shortcut, and the keys that drive a live expansion session. Nothing here reuses Roslyn: its snippet stack is `internal` under `LanguageServices.Implementation.Snippets` with no ExternalAccess surface, so F# writes its own `IVsExpansionClient` the way it already writes its own brace completion. The commands come in through one MEF `ICommandHandler<_>` part, ordered after the completion handler so that Tab still commits an open completion list first. Indentation is the F#-specific part. The expansion engine inserts snippet text verbatim, and C# gets away with that because Roslyn's formatter reflows the result afterwards; F# has no formatter, so `FormatSpan` computes the columns. That arithmetic lives in `SnippetIndentation`, free of editor types so that it can be tested on its own - the policy is where the mistakes live, not the buffer edit that applies it. A directive wrapper is its own line kind: `#if`/`#else`/`#endif` and the scoped `#nowarn`/`#warnon` pair read at the left margin whatever they wrap, so the code they cover keeps the column it had. Two things worth knowing for anyone reading `IVsExpansionClient` next to Roslyn's: `tsInsertPos` is the range `InsertNamedExpansion` replaces, so handing it the selection deletes the code a SurroundsWith snippet was meant to wrap; and `GetFieldSpan "selected"` does not answer for that special literal, so the substituted range is derived from the template's own `$selected$` line plus the line count the command handler took before the insertion. `ClassName()` and `GenerateMatchCases()` back the `ctor`, `equals` and `match` snippets. Both are synchronous COM callbacks, so they block; `ClassName()` blocks on a parse and `GenerateMatchCases()` on the stale-tolerant check-results path, falling back to a visible `| _ -> ()` rather than waiting unbounded. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A RequireQualifiedAccess union rejects a bare case pattern (`A`, not `U.A`) - the
generated pattern binds a fresh variable instead of testing the case, so it takes the
first arm regardless of the actual value. matchRulesFor now qualifies with the
entity's DisplayName when the union carries the attribute, the same way it already
does for enums.
ClassName() used the navigation item's LogicalName, which is qualified by every
enclosing module ("Outer.C") - it does not resolve from a constructor sitting inside
C's own scope. Strips to the name after the last '.'.
GenerateMatchCases() resolved the lexer symbol nearest the field's end position,
which is whatever identifier happens to sit there - for `f x`, that is `x`, not the
call `f x`. Reads the type the checker captured for the field's whole span instead
(TryGetCapturedType), so it matches the expression's own result type regardless of
its shape.
Surround With reindented every non-first selected line uniformly, including a line
that is itself inside a multi-line string continued from an earlier selected line -
inserting indentation there changes the string's value, not just its position.
classifyLines now threads the lexer's color state across the span and classifies
such a line as InsideString, left untouched like a blank line.
lock.snippet closed the lambda on the same line as $selected$$end$, so a selection
whose last line ends in a trailing // comment swallowed the closing paren into the
comment, leaving the call unclosed. Moved onto its own line, matching how the other
wrapping snippets already close.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
A match on a union or enum now spells its cases with the shortest qualifier that resolves at the insertion point, asked of the checked file the way the simplify-names analyzer asks it, instead of assuming `DisplayName.` is reachable: a `[<RequireQualifiedAccess>]` union in an unopened module produced `U.A`, which does not resolve. The expression's captured type is used as it stands, so matching a function value no longer generates the arms of its result type. Indentation is measured in visual columns. A snippet expanded after a tab took the character count as its column and came out one space in, and Surround With over tab-indented code wrapped it at the wrong column. A cancelled Surround With never reports back, so its pending selection was still set when the next shortcut expanded; the shortcut path now clears it. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Expands and surrounds like `task`, for code that has to run off the caller's context. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Fixes #1498
Adds Visual Studio code-snippet support for F#:
Ctrl+K,Ctrl+Xinserts a snippet,Ctrl+K,Ctrl+Ssurrounds a selection, and a snippet shortcut expands on Tab. Ships a built-in catalog matching C#'s (declarations, members, control flow, computation expressions);ctor/equalsfill in the enclosing type name andmatchgenerates the cases of the union or enum it is given.Verified by hand in the experimental hive in addition to the added tests.
Not in scope: snippet shortcuts as an IntelliSense completion item (as C# offers), localized snippet folders,
<Imports>/<References>support, and snippets for test methods.Checklist
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