Add MemoryExtensions.CommonPrefixLength (#67929)

* Add MemoryExtensions.CommonPrefixLength

* Remove unnecessary constraint (and default argument)

* Address PR feedback

Author: stephentoub

src/libraries/System.Memory/System.Memory.sln

@@ -1,4 +1,8 @@
-Microsoft Visual Studio Solution File, Format Version 12.00
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.3.32412.434
+MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "System.Private.CoreLib", "..\..\coreclr\System.Private.CoreLib\System.Private.CoreLib.csproj", "{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestUtilities", "..\Common\tests\TestUtilities\TestUtilities.csproj", "{6A54FACA-933E-4C1D-92AB-1A5506CFC212}"
@@ -25,17 +29,23 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "gen", "gen", "{2BEB1A89-DD2
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Checked|Any CPU = Checked|Any CPU
+		Checked|x64 = Checked|x64
+		Checked|x86 = Checked|x86
 		Debug|Any CPU = Debug|Any CPU
 		Debug|x64 = Debug|x64
 		Debug|x86 = Debug|x86
 		Release|Any CPU = Release|Any CPU
 		Release|x64 = Release|x64
 		Release|x86 = Release|x86
-		Checked|Any CPU = Checked|Any CPU
-		Checked|x64 = Checked|x64
-		Checked|x86 = Checked|x86
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|Any CPU.ActiveCfg = Checked|x64
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|Any CPU.Build.0 = Checked|x64
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x64.ActiveCfg = Checked|x64
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x64.Build.0 = Checked|x64
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x86.ActiveCfg = Checked|x86
+		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x86.Build.0 = Checked|x86
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Debug|Any CPU.ActiveCfg = Debug|x64
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Debug|Any CPU.Build.0 = Debug|x64
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Debug|x64.ActiveCfg = Debug|x64
@@ -48,12 +58,12 @@ Global
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Release|x64.Build.0 = Release|x64
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Release|x86.ActiveCfg = Release|x86
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Release|x86.Build.0 = Release|x86
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|Any CPU.ActiveCfg = Checked|x64
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|Any CPU.Build.0 = Checked|x64
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x64.ActiveCfg = Checked|x64
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x64.Build.0 = Checked|x64
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x86.ActiveCfg = Checked|x86
-		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22}.Checked|x86.Build.0 = Checked|x86
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x64.Build.0 = Debug|Any CPU
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x86.Build.0 = Debug|Any CPU
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -66,12 +76,12 @@ Global
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Release|x64.Build.0 = Release|Any CPU
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Release|x86.ActiveCfg = Release|Any CPU
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Release|x86.Build.0 = Release|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x64.Build.0 = Debug|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{6A54FACA-933E-4C1D-92AB-1A5506CFC212}.Checked|x86.Build.0 = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x64.Build.0 = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x86.Build.0 = Debug|Any CPU
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -84,12 +94,12 @@ Global
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Release|x64.Build.0 = Release|Any CPU
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Release|x86.ActiveCfg = Release|Any CPU
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Release|x86.Build.0 = Release|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x64.Build.0 = Debug|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{9112BAE3-344D-4DD0-ADC9-478D82B84584}.Checked|x86.Build.0 = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x64.Build.0 = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x86.Build.0 = Debug|Any CPU
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -102,12 +112,12 @@ Global
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Release|x64.Build.0 = Release|Any CPU
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Release|x86.ActiveCfg = Release|Any CPU
 		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Release|x86.Build.0 = Release|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x64.Build.0 = Debug|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92}.Checked|x86.Build.0 = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x64.Build.0 = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x86.Build.0 = Debug|Any CPU
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -120,12 +130,12 @@ Global
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Release|x64.Build.0 = Release|Any CPU
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Release|x86.ActiveCfg = Release|Any CPU
 		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Release|x86.Build.0 = Release|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x64.Build.0 = Debug|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297}.Checked|x86.Build.0 = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x64.Build.0 = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x86.Build.0 = Debug|Any CPU
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -138,12 +148,12 @@ Global
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Release|x64.Build.0 = Release|Any CPU
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Release|x86.ActiveCfg = Release|Any CPU
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Release|x86.Build.0 = Release|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x64.Build.0 = Debug|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{EFF00253-633C-4D2F-86EE-F40C721F6A68}.Checked|x86.Build.0 = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x64.Build.0 = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x86.Build.0 = Debug|Any CPU
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -156,12 +166,12 @@ Global
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Release|x64.Build.0 = Release|Any CPU
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Release|x86.ActiveCfg = Release|Any CPU
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Release|x86.Build.0 = Release|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x64.Build.0 = Debug|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7}.Checked|x86.Build.0 = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|Any CPU.Build.0 = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x64.ActiveCfg = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x64.Build.0 = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x86.ActiveCfg = Debug|Any CPU
+		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x86.Build.0 = Debug|Any CPU
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -174,27 +184,24 @@ Global
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Release|x64.Build.0 = Release|Any CPU
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Release|x86.ActiveCfg = Release|Any CPU
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Release|x86.Build.0 = Release|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|Any CPU.ActiveCfg = Debug|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|Any CPU.Build.0 = Debug|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x64.ActiveCfg = Debug|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x64.Build.0 = Debug|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x86.ActiveCfg = Debug|Any CPU
-		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F}.Checked|x86.Build.0 = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{7746BFD6-E6D6-4703-AA2D-43380B5DEA22} = {C352AC7D-959D-431F-AF83-2CA506B70D59}
-		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92} = {C352AC7D-959D-431F-AF83-2CA506B70D59}
 		{6A54FACA-933E-4C1D-92AB-1A5506CFC212} = {FA259C32-B79B-4DE2-9677-055D5D25FA33}
-		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297} = {FA259C32-B79B-4DE2-9677-055D5D25FA33}
 		{9112BAE3-344D-4DD0-ADC9-478D82B84584} = {7212FBCF-E89D-4065-9DCE-D5F7E5D3EF1D}
+		{C9417154-D8DB-4FF9-9DD8-6B2ED351FC92} = {C352AC7D-959D-431F-AF83-2CA506B70D59}
+		{C2BC6AE7-7E8B-4AA2-8E9F-5D4B9127B297} = {FA259C32-B79B-4DE2-9677-055D5D25FA33}
 		{EFF00253-633C-4D2F-86EE-F40C721F6A68} = {2BEB1A89-DD2D-42BD-95DD-89860A0C9663}
 		{84AD7BF6-D76C-4BEE-9879-5A23150DD3F7} = {2BEB1A89-DD2D-42BD-95DD-89860A0C9663}
 		{DA7CEED7-1A86-4221-B4AD-4307AB83A31F} = {2BEB1A89-DD2D-42BD-95DD-89860A0C9663}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {65DB6A6B-0AAC-4BC2-A61A-641679771DC7}
 	EndGlobalSection
+	GlobalSection(SharedMSBuildProjectFiles) = preSolution
+		..\System.Private.CoreLib\src\System.Private.CoreLib.Shared.projitems*{7746bfd6-e6d6-4703-aa2d-43380b5dea22}*SharedItemsImports = 5
+	EndGlobalSection
 EndGlobal

src/libraries/System.Memory/ref/System.Memory.cs

@@ -40,6 +40,10 @@ public static partial class MemoryExtensions
         public static int BinarySearch<T, TComparable>(this System.ReadOnlySpan<T> span, TComparable comparable) where TComparable : System.IComparable<T> { throw null; }
         public static int BinarySearch<T, TComparer>(this System.Span<T> span, T value, TComparer comparer) where TComparer : System.Collections.Generic.IComparer<T> { throw null; }
         public static int BinarySearch<T, TComparable>(this System.Span<T> span, TComparable comparable) where TComparable : System.IComparable<T> { throw null; }
+        public static int CommonPrefixLength<T>(this System.Span<T> span, System.ReadOnlySpan<T> other) { throw null; }
+        public static int CommonPrefixLength<T>(this System.Span<T> span, System.ReadOnlySpan<T> other, System.Collections.Generic.IEqualityComparer<T>? comparer) { throw null; }
+        public static int CommonPrefixLength<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> other) { throw null; }
+        public static int CommonPrefixLength<T>(this System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> other, System.Collections.Generic.IEqualityComparer<T>? comparer) { throw null; }
         public static int CompareTo(this System.ReadOnlySpan<char> span, System.ReadOnlySpan<char> other, System.StringComparison comparisonType) { throw null; }
         public static bool Contains(this System.ReadOnlySpan<char> span, System.ReadOnlySpan<char> value, System.StringComparison comparisonType) { throw null; }
         public static bool Contains<T>(this System.ReadOnlySpan<T> span, T value) where T : System.IEquatable<T> { throw null; }