for loop with multiple uninitialized variables no longer compiles #77160
Description
Version Used: .NET SDK 9.0.200
Steps to Reproduce:
- Clone https://github.com/jonsagara/ForLoopCompileTest
- Open the solution
- Build -> Rebuild Solution
In a nutshell, a for loop with two or more uninitialized variables breaks compilation:
for (int offset = 0, c1, c2; offset < length;)
{
// snipped
}But a single uninitialized loop variable compiles:
for (int offset = 0, c1; offset < length;)
{
// snipped
}Expected Behavior:
This loop is extracted from a file that has been part of our solution since 2016. The for loop itself has never changed. I expect it to still compile.
Actual Behavior:
You get compilation errors. From the solution listed above, you get compiler errors like these:
; expected
The name 'c1' does not exist in the current context
; expected
The name 'c2' does not exist in the current context
Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
Syntax error, ',' expected
Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
Syntax error, ',' expected
Invalid expression term ')'
; expected
The name 'c1' does not exist in the current context
; expected
The name 'c2' does not exist in the current context
Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
The name 'c3' does not exist in the current context
Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
Syntax error, ',' expected
Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement
Syntax error, ',' expected
Invalid expression term ')'
Environment
- Visual Studio 2022 17.13
- Visual Studio 2022 17.14.0 Preview 1.0
- .NET SDK 9.0.200
- Windows 11 Version 24H2 (OS Build 26100.3194)
JetBrains Rider
The solution also fails to compile in JetBrains Rider 2024.3.5.
Previous reports
I reported this to VS Feedback when I first encountered it.