Breakpoints on pipeline stages by dsyme · Pull Request #11957 · dotnet/fsharp ·...

This adds breakpoints and stepping on stages in F# forward piping in debug code.

Spec (debug codegen only)

Breakpoint validity

For expr |> f1 |> f2 ... |> fLast , a breakpoint is valid on the expression that is an input to a pipeline, and any "stage" of a pipeline.

Similarly, for (expr1, expr2) ||> f1 |> f2 ... |> fLast and (expr1, expr2, expr3) |||> f1 |> f2 ... |> fLast` , a breakpoint is valid on each of the input expressions, and any "stage" of a pipeline.

Sequence point emit

A corresponding sequence point is emitted in .NET IL before the evaluation of expr and before applying each of f1, f2 etc.

Locals

• A local value Pipe #m input #n @ line is shown within f1, f2, f3, ...for the corresponding value of expr. The pipe number is the occurrence of piping within the method. The n it the input number (elided if only one input). The line is the line number where the input expression occurs.

• A local value Pipe #m stage 1 @ line is shown within f2, f3, ... for the corresponding value of expr |> f1

• A local value Pipe #m stage 2 @ line is shown within f3, ... for the corresponding value of expr |> f1 |> f2

The names of the locals are emitted in IL code and are not localized (as that would make compiler output dependent on localization).

Sample screen capture below (stepping) - the local values names differ slightly from the above spec

a.Debugging.-.Microsoft.Visual.Studio.Administrator.2021-08-12.15-17-03.mp4

And with breakpoints:

a.-.Microsoft.Visual.Studio.Administrator.2021-08-12.15-54-23.mp4