Update pattern matching error message.

[isaacabraham]

This is a small change that (IMO) improves the error message displayed when different branches of a pattern match return values of different types.

Before

All branches of a pattern match expression must have the same type. This expression was expected to have type 'string', but here has type 'int'.

After

All branches of a pattern match expression must return values of the same type. The first branch returned a value of type 'string', but this branch returned a value of type 'int'."

[vasily-kirichenko]

Excellent, the message has always been tricky to understand.

[cartermp]

I like this change a lot.

[forki]

We have no tests?

[KevinRansom]

@isaacabraham I'll take care of the errors.

[cloudRoutine]

shouldn't it still be return expressions and returned an expression ?

[isaacabraham]

Hmmmm. I'm not sure :-)

[isaacabraham]

@KevinRansom I'm not sure what the error is anyway - can you explain for future reference? Thanks!

[KevinRansom]

The error is:

  D:\j\w\release_ci_pa---3f142ccc\packages\XliffTasks.0.2.0-beta-000081\build\XliffTasks.targets(90,5): error : '..\xlf\FSComp.txt.en.xlf' is out-of-date with 'obj\release\net40\FSComp.resx'. 
Run `msbuild /t:UpdateXlf` to update .xlf files or set UpdateXlfOnBuild=true to update them on every build, but note that it is strongly discouraged to set UpdateXlfOnBuild=true 
in official/CI build environments as they should not modify source code during the build. [D:\j\w\release_ci_pa---3f142ccc\src\fsharp\FSharp.Compiler.Private\FSharp.Compiler.Private.fsproj]

The fix is to run :

msbuild D:\j\w\release_ci_pa---3f142ccc\src\fsharp\FSharp.Compiler.Private\FSharp.Compiler.Private.fsproj /t:UpdateXlf
then add and commit the updtaed .xlf files.

[KevinRansom]

@isaacabraham
and actual test errors.

The expected text needs updating

Errors and Failures

1) Error : FSharp-Tests-Core+TypecheckTests.type check neg20
System.Exception : neg20.err neg20.bsl differ; "diff between [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg20.bsl] and [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg20.err]
line 115
 - neg20.fs(87,54,87,61): typecheck error FS0001: All branches of a pattern match expression must have the same type. This expression was expected to have type 'B', but here has type 'C'.
 + neg20.fs(87,54,87,61): typecheck error FS0001: All branches of a pattern match expression must return values of the same type. The first branch returned a value of type 'B', but this branch returned a value of type 'C'.
"; neg20.vserr neg20.bsl differ; "diff between [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg20.bsl] and [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg20.vserr]
line 115
 - neg20.fs(87,54,87,61): typecheck error FS0001: All branches of a pattern match expression must have the same type. This expression was expected to have type 'B', but here has type 'C'.
 + neg20.fs(87,54,87,61): typecheck error FS0001: All branches of a pattern match expression must return values of the same type. The first branch returned a value of type 'B', but this branch returned a value of type 'C'.
"
   at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@1645.Invoke(String message) in D:\j\w\release_ci_pa---866fd2c3\src\fsharp\FSharp.Core\printf.fs:line 1645

2) Error : FSharp-Tests-Core+TypecheckTests.type check neg80
System.Exception : neg80.vserr neg80.vsbsl differ; "diff between [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg80.vsbsl] and [D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\typecheck\sigs\neg80.vserr]
line 6
 - neg80.fsx(79,6,79,6): typecheck error FS0001: All branches of a pattern match expression must have the same type. This expression was expected to have type 'string', but here has type 'unit'.
 + neg80.fsx(79,6,79,6): typecheck error FS0001: All branches of a pattern match expression must return values of the same type. The first branch returned a value of type 'string', but this branch returned a value of type 'unit'.
"
   at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@1645.Invoke(String message) in D:\j\w\release_ci_pa---866fd2c3\src\fsharp\FSharp.Core\printf.fs:line 1645
   at SingleTest.singleNegTest(TestConfig cfg, String testname) in D:\j\w\release_ci_pa---866fd2c3\tests\fsharp\single-test.fs:line 235

R

[KevinRansom]

@dotnet-bot test Ubuntu16.04 Release_default Build please

[KevinRansom]

@isaacabraham

Thank you.

[isaacabraham]

Thank you for fixing the tests. Next time I'll check that stuff myself, now that I know what's needed!

[KevinRansom]

Thank for the PR.