Changing the hardcoded g prefix

src/NerdBank.GitVersioning.Tests/VersionFileTests.cs

@@ -146,6 +146,7 @@ public void SetVersion_WritesSimplestFile(string version, string assemblyVersion
     [InlineData(@"{""release"":{""increment"":""minor""}}", @"{}")]
     [InlineData(@"{""release"":{""branchName"":""v{version}""}}", @"{}")]
     [InlineData(@"{""release"":{""firstUnstableTag"":""alpha""}}", @"{}")]
+    [InlineData(@"{""release"":{""gitCommitIdPrefix"":""g""}}", @"{}")]
     [InlineData(@"{""release"":{""firstUnstableTag"":""tag""}}", @"{""release"":{""firstUnstableTag"":""tag""}}")]
     [InlineData(@"{""release"":{""branchName"":""v{version}"",""versionIncrement"":""minor"",""firstUnstableTag"":""alpha""}}", @"{}")]
     [InlineData(@"{""release"":{""versionIncrement"":""major""}}", @"{""release"":{""versionIncrement"":""major""}}")]

src/NerdBank.GitVersioning.Tests/VersionOptionsTests.cs

@@ -202,7 +202,7 @@ public void ReleaseOptions_Equality()
         var ro5 = new VersionOptions.ReleaseOptions()
         {
             BranchName = "branchName",
-            VersionIncrement = VersionOptions.ReleaseVersionIncrement.Minor,            
+            VersionIncrement = VersionOptions.ReleaseVersionIncrement.Minor,
         };
         var ro6 = new VersionOptions.ReleaseOptions()
         {

src/NerdBank.GitVersioning.Tests/VersionOracleTests.cs

@@ -313,6 +313,25 @@ public void CanSetSemVer2ForNuGetPackageVersionNonPublicRelease()
         Assert.Equal($"7.8.9-foo.25.g{this.CommitIdShort}", oracle.NuGetPackageVersion);
     }
 
+    [Fact]
+    public void CanSetGitCommitIdPrefixNonPublicRelease()
+    {
+        VersionOptions workingCopyVersion = new VersionOptions
+        {
+            Version = SemanticVersion.Parse("7.8.9-foo.25"),
+            NuGetPackageVersion = new VersionOptions.NuGetPackageVersionOptions
+            {
+                SemVer = 2,
+            },
+            GitCommitIdPrefix = "git",
+        };
+        this.WriteVersionFile(workingCopyVersion);
+        this.InitializeSourceControl();
+        var oracle = VersionOracle.Create(this.RepoPath);
+        oracle.PublicRelease = false;
+        Assert.Equal($"7.8.9-foo.25.git{this.CommitIdShort}", oracle.NuGetPackageVersion);
+    }
+
     [Fact]
     public void CanUseGitProjectRelativePathWithGitRepoRoot()
     {

src/NerdBank.GitVersioning/VersionOptions.cs

@@ -15,6 +15,9 @@
     [DebuggerDisplay("{DebuggerDisplay,nq}")]
     public class VersionOptions : IEquatable<VersionOptions>
     {
+        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+        private string gitCommitIdPrefix;
+
         /// <summary>
         /// Default value for <see cref="VersionPrecision"/>.
         /// </summary>
@@ -60,6 +63,32 @@ public class VersionOptions : IEquatable<VersionOptions>
         [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
         public AssemblyVersionOptions AssemblyVersion { get; set; }
 
+
+        /// <summary>
+        /// Gets or sets the prefix for git commit id in version.
+        /// Because of semver rules the prefix must lead with a [A-z_] character (not a number) and it cannot be the empty string.
+        /// If <c>null</c> 'g' will be used.
+        /// </summary>
+        /// <value>A prefix for git commit id.</value>
+        [JsonProperty(DefaultValueHandling = DefaultValueHandling.Ignore)]
+        public string GitCommitIdPrefix
+        {
+            get => gitCommitIdPrefix;
+            set
+            {
+                if (string.IsNullOrWhiteSpace(value))
+                {
+                    throw new ArgumentNullException(nameof(value), $"{nameof(this.GitCommitIdPrefix)} can't be empty");
+                }
+                char first = value[0];
+                if (first < 'A' || (first > 'Z' && first < 'a' && first != '_') || first > 'z')
+                {
+                    throw new ArgumentException(nameof(value), $"{nameof(this.GitCommitIdPrefix)} must lead with a [A-z_] character (not a number)");
+                }
+                this.gitCommitIdPrefix = value;
+            }
+        }
+
         /// <summary>
         /// Gets the version to use particularly for the <see cref="AssemblyVersionAttribute"/>
         /// instead of the default <see cref="Version"/>.

src/NerdBank.GitVersioning/VersionOracle.cs

@@ -409,7 +409,7 @@ public IEnumerable<string> BuildMetadataWithCommitId
         /// See <see href="https://github.com/dotnet/Nerdbank.GitVersioning/issues/260#issuecomment-445511898">this discussion</see>.
         /// </remarks>
         private string NuGetSemVer1BuildMetadata =>
-            this.PublicRelease ? string.Empty : $"-g{this.GitCommitIdShort}";
+            this.PublicRelease ? string.Empty : $"-{this.VersionOptions?.GitCommitIdPrefix ?? "g"}{this.GitCommitIdShort}";
 
         /// <summary>
         /// Gets the build metadata, compliant to SemVer 1.0.
@@ -439,12 +439,13 @@ public IEnumerable<string> BuildMetadataWithCommitId
 
         /// <summary>
         /// Gets the -gc0ffee or .gc0ffee suffix for the version.
+        /// The g in the prefix might be changed if <see cref="VersionOptions.GitCommitIdPrefix"/> is set.
         /// </summary>
         /// <remarks>
-        /// The `g` prefix to the commit ID is to remain SemVer2 compliant particularly when the partial commit ID we use is made up entirely of numerals.
-        /// SemVer2 forbids numerals to begin with leading zeros, but a git commit just might, so we begin with `g` always to avoid failures when the commit ID happens to be problematic.
+        /// The prefix to the commit ID is to remain SemVer2 compliant particularly when the partial commit ID we use is made up entirely of numerals.
+        /// SemVer2 forbids numerals to begin with leading zeros, but a git commit just might, so we begin with prefix always to avoid failures when the commit ID happens to be problematic.
         /// </remarks>
-        private string GitCommitIdShortForNonPublicPrereleaseTag => (string.IsNullOrEmpty(this.PrereleaseVersion) ? "-" : ".") + "g" + this.GitCommitIdShort;
+        private string GitCommitIdShortForNonPublicPrereleaseTag => (string.IsNullOrEmpty(this.PrereleaseVersion) ? "-" : ".") + (this.VersionOptions?.GitCommitIdPrefix ?? "g") + this.GitCommitIdShort;
 
         private VersionOptions.CloudBuildNumberOptions CloudBuildNumberOptions { get; }
 

src/NerdBank.GitVersioning/version.schema.json

@@ -79,6 +79,12 @@
           "default": 10,
           "maximum": 40
         },
+        "gitCommitIdPrefix": {
+          "type": "string",
+          "description": "The git commit prefix (e.g. 'g') in non-public release versions.",
+          "pattern": "^[^0-9][\\da-z\\-_\\.]*$",
+          "default": "g"
+        },
         "gitCommitIdShortAutoMinimum": {
           "type": "integer",
           "description": "When greater than 0, the length of the commit ID will be either this value or the shortest unambiguous git-abbreviated commit ID possible, whichever is greater. When 0, the gitCommitIdShortFixedLength property is used instead.",