Kirill Osenkov
LightNews LightNews
banner
kirillosenkov.com
Kirill Osenkov
@kirillosenkov.com
1.4K followers 250 following 530 posts
(Unofficial) VP of Developer Productivity at Microsoft. Developer tools, engineering systems, .NET, C#, Roslyn, Visual Studio, Editor, WPF, Avalonia, MSBuild.
Posts Replies Media Videos
kirillosenkov.com
New in MSBuild Structured Log Viewer:

property trail showing reads and writes during evaluation, in order:

github.com/KirillOsenko...

If you've ever had ordering issues where someone reads your property before you wrote to it, this is the tool for you.
Screenshot showing a search box on top with $property and three property names such as DebugType, and lower the search results in the form of a tree, showing reads and writes of those MSBuild properties.
November 7, 2025 at 3:04 AM
kirillosenkov.com
Fun fun fun
car dashboard screen saying in red Stop vehicle and check power supply
October 11, 2025 at 7:17 AM
kirillosenkov.com
I even see which repository it was (it has been deleted or made private), but there's no way to clear or delete it:
screenshot of GitHub UI showing one repo in the Repositories list, called paradigm-notify/paradigm
September 29, 2025 at 2:34 AM
kirillosenkov.com
I just wrote a Roslyn refactoring! I have to say the Roslyn API is beautiful and I loved the experience.

gist.github.com/KirillOsenko...
VS editor with a lightbulb on params keyword, offering a Convert call sites to use arrays refactoring with a preview diff that shows square brackets added around an argument to a method
September 26, 2025 at 1:02 AM
kirillosenkov.com
Phantom notifications bother me way more than they should
screenshot of GitHub showing me that I have notifications, but I have no notifications
September 18, 2025 at 3:09 AM
kirillosenkov.com
I just learned that Directory.GetFiles with pattern 1.txt.* matches 1.txt, and it's the OS behavior:
dir 1.txt.* matches 1.txt
September 5, 2025 at 6:07 PM
kirillosenkov.com
OK I really don't like what's going on here:
comparison results of AB and ab, BA and Ba for CurrentCulture in various casings. It's either 1 or -1. "Ab", "ab" 1 "aB", "ab" 1 "ab", "Ab" -1 "ab", "aB" -1 "AB", "ab" 1 "Ab", "aB" 1 "Ba", "ba" 1 "bA", "ba" 1 "ba", "Ba" -1 "ba", "bA" -1 "BA", "ba" 1 "Ba", "bA" 1
August 25, 2025 at 5:37 AM
kirillosenkov.com
Hmm, I have to confess, this is unexpected for me. Lowercase letters come before uppercase? Intuitively it feels that uppercase should come first?
six different ways to sort a string array with InvariantCultureIgnoreCase, CurrentCultureIgnoreCase, OrdinalIgnoreCase, etc. Lowercase letters appear before uppercase letters except for Ordinal
August 25, 2025 at 5:09 AM
kirillosenkov.com
Just saw an Ioniq 5 N on the road for the first time, looks great
dark gray car from the back, in a sunlit road
August 21, 2025 at 4:49 PM
kirillosenkov.com
sign: no cash? exit this way
August 9, 2025 at 4:50 PM
kirillosenkov.com
I was always annoyed by the StringBuilder API Append/AppendLine and that it returns a StringBuilder, so not convertible to an Action<string>.

I have recently started using StringWriter instead (it's a very thin wrapper around StringBuilder), but now it's a proper TextWriter, and I'm very happy.
Drake meme: disapproval: StringBuilder approval: StringWriter
August 2, 2025 at 10:34 PM
kirillosenkov.com
added MSBuild target graph visualizer too:
Screenshot of MSBuild binlog viewer. At the center is the new Targets tab which displays a graph of rectangles, each rectangle has the target name. Selected target has outgoing dependencies on other targets above it, and targets below it have incoming references to the selected target. On the right the graph is displayed as text in Dot format. On the left the search for the current target displays all DependsOnTargets, BeforeTargets and AfterTargets for the current target.
July 30, 2025 at 9:01 PM
kirillosenkov.com
yes, your problem is Kahua.generators.dll

not sure what that is, clearly some third-party thing
call stack screenshot with Kahua.Generators.dll calling into Roslyn
July 29, 2025 at 5:46 PM
kirillosenkov.com
Happy "Unicode calendar emoji shows the actual current date" day to all those who celebrate:

quickinfo.io?calendar
Unicode character U+1F4C5 is a calendar showing July 17
July 17, 2025 at 6:55 PM
kirillosenkov.com
New in MSBuild Structured Log Viewer:

Project Reference Graph

New tab that shows the project graph layered by project "height". Each project only references projects above it.

Clicking a project highlights all directly referenced projects above, and all projects below it that reference this one.
many rows of multiple rectangles per row, each rectangle is the project name, some rectangles are bigger and bluer (they are referenced more). One rectangle is selected and green, it has outgoing arrows above it that point to other rectangles, with purple border. Those are the referenced projects. Arrows also go down, to rectangles with green borders. Those are projects that reference the selected one.
June 21, 2025 at 2:33 AM
kirillosenkov.com
Ran into the situation again where updating VS broke incremental builds, because a different compiler version is now being stamped into the embedded PDB, invalidating all caches and resulting in different PE file bytes from identical sources.

Glad I invested in the fancy PE parser and differ!
Screenshot of a fancy diff tool with a tree on the left which shows the PE file structure all the way down into the embedded PDB stream, showing different compiler version and runtime version between left and right. Some bytes in the hex editor on the right.
May 31, 2025 at 8:39 PM
kirillosenkov.com
I wrote a simple tokenizer and translator from Mandarin to English, that translates per-word, as opposed to whole sentences. Turns out both the tokenizer and the dictionary are freely available and open-source, so I just added them to quickinfo.io:

quickinfo.io?%E6%88%91%E7...
screenshot of quickinfo.io showing a sentence in Chinese consisting of six characters, and each word has the Pinyin pronunciation and the English translations under it
May 27, 2025 at 1:23 AM
kirillosenkov.com
screenshot of an 8x8 game square where each square is a different color and a power of two, no three same numbers are in a row, high score is 9948
May 21, 2025 at 3:59 PM
kirillosenkov.com
I don't tweet enough about how amazing the Ultra profiler is:

github.com/xoofx/ultra
Screenshot of a .NET application (MSBuild) profile open in Firefox profiler flame graph. You can see managed frames, native frames, GC, allocations and even time in Kernel.
May 20, 2025 at 6:25 PM
kirillosenkov.com
New feature in MSBuild Structured Log Viewer: Target Graph!

It parses the preprocessed XML and constructs the target graph where edges are BeforeTargets, DependsOnTargets and AfterTargets.
Screenshot of binlog viewer search query $target CoreCompile project, the result tree includes folders: Graph, DependsOnTargets, Targets that run before CoreCompile, targets that run after CoreCompile and targets that depend on CoreCompile
May 12, 2025 at 4:21 AM
kirillosenkov.com
MSBuild target graph. Hope it helps!
unreadable fuzzy blob of black text on white background with lines so entangled as to be completely useless
April 25, 2025 at 2:36 AM
kirillosenkov.com
Protest against Trump and Musk in downtown Bellevue 🇺🇦
people on the street protesting with Ukrainian flags
March 1, 2025 at 7:33 PM
kirillosenkov.com
there's also this:
github.com/KirillOsenko...
screenshot of MSBuild structured log viewer showing a tree of NuGet package dependencies with yellow highlighted search terms
February 3, 2025 at 7:58 AM
kirillosenkov.com
Turns out when Roslyn ships a new compiler it invalidates all deterministic assemblies compiled with the previous compiler that embed the pdb, because the pdb contains the SHA of the compiler:
Screenshot of an assembly diff tool that shows a treeview where two nodes are different (red and green): compiler-version and runtime-version, showing slightly incremented Roslyn compiler versions
January 20, 2025 at 7:30 AM
kirillosenkov.com
I just needed a cross product for the first time ever so I wrote a Linq-like one:
public static IEnumerable<R> CrossProduct<T, U, R>(this IEnumerable<T> left, IEnumerable<U> right, Func<T, U, R> func) { // avoid multiple enumeration of the right enumerable var rightArray = right.ToArray(); foreach (var leftItem in left) { foreach (var rightItem in rightArray) { var result = func(leftItem, rightItem); yield return result; } } }
January 12, 2025 at 5:24 AM