Expand #error version output to include compiler assembly path and use full commit SHA everywhere

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -5460,7 +5460,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
     <value>Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.</value>
   </data>
   <data name="ERR_CompilerAndLanguageVersion" xml:space="preserve">
-    <value>Compiler version: '{0}'. Language version: {1}.</value>
+    <value>Compiler version: '{0}'. Language version: {1}. Compiler path: '{2}'.</value>
   </data>
   <data name="IDS_FeatureAsyncMain" xml:space="preserve">
     <value>async main</value>

src/Compilers/CSharp/Portable/Parser/DirectiveParser.cs

@@ -333,13 +333,14 @@ private DirectiveTriviaSyntax ParseErrorOrWarningDirective(SyntaxToken hash, Syn
                     if (errorText.Equals("version", StringComparison.Ordinal))
                     {
                         string version = CommonCompiler.GetProductVersion(typeof(CSharpCompiler));
+                        string assemblyPath = CommonCompiler.GetAssemblyLocation(typeof(CSharpCompiler));
                         var specified = this.Options.SpecifiedLanguageVersion;
                         var effective = specified.MapSpecifiedToEffectiveVersion();
 
                         var displayLanguageVersion = specified == effective ? specified.ToDisplayString() : $"{specified.ToDisplayString()} ({effective.ToDisplayString()})";
 
                         eod = this.AddError(eod, triviaOffset, triviaWidth, ErrorCode.ERR_CompilerAndLanguageVersion, version,
-                            displayLanguageVersion);
+                            displayLanguageVersion, assemblyPath);
                     }
                     else
                     {

src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs

@@ -7052,19 +7052,6 @@ private static string ReplaceCommitHash(string s)
             return Regex.Replace(s, "(\\((<developer build>|[a-fA-F0-9]{8})\\))", "(HASH)");
         }
 
-        [Fact]
-        public void ExtractShortCommitHash()
-        {
-            Assert.Null(CommonCompiler.ExtractShortCommitHash(null));
-            Assert.Equal("", CommonCompiler.ExtractShortCommitHash(""));
-            Assert.Equal("<", CommonCompiler.ExtractShortCommitHash("<"));
-            Assert.Equal("<developer build>", CommonCompiler.ExtractShortCommitHash("<developer build>"));
-            Assert.Equal("1", CommonCompiler.ExtractShortCommitHash("1"));
-            Assert.Equal("1234567", CommonCompiler.ExtractShortCommitHash("1234567"));
-            Assert.Equal("12345678", CommonCompiler.ExtractShortCommitHash("12345678"));
-            Assert.Equal("12345678", CommonCompiler.ExtractShortCommitHash("123456789"));
-        }
-
         private void CheckOutputFileName(string source1, string source2, string inputName1, string inputName2, string[] commandLineArguments, string expectedOutputName)
         {
             var dir = Temp.CreateDirectory();

src/Compilers/CSharp/Test/Syntax/LexicalAndXml/PreprocessorTests.cs

@@ -3242,9 +3242,9 @@ public void TestErrorWithVersion(LanguageVersion version, string expectedLanguag
                 // (1,8): error CS1029: #error: 'version'
                 // #error version
                 Diagnostic(ErrorCode.ERR_ErrorDirective, "version").WithArguments("version").WithLocation(1, 8),
-                // (1,8): error CS8304: Compiler version: '42.42.42.42424 (<developer build>)'. Language version: <expectedLanguageVersion>.
+                // (1,8): error CS8304: Compiler version: '42.42.42.42424 (<developer build>)'. Language version: <expectedLanguageVersion>. Compiler path: '<path>'.
                 // #error version
-                Diagnostic(ErrorCode.ERR_CompilerAndLanguageVersion, "version").WithArguments(GetExpectedVersion(), expectedLanguageVersion).WithLocation(1, 8)
+                Diagnostic(ErrorCode.ERR_CompilerAndLanguageVersion, "version").WithArguments(GetExpectedVersion(), expectedLanguageVersion, GetExpectedAssemblyPath()).WithLocation(1, 8)
                 );
         }
 
@@ -4659,5 +4659,10 @@ private static string GetExpectedVersion()
         {
             return CommonCompiler.GetProductVersion(typeof(CSharpCompiler));
         }
+
+        private static string GetExpectedAssemblyPath()
+        {
+            return CommonCompiler.GetAssemblyLocation(typeof(CSharpCompiler));
+        }
     }
 }

src/Compilers/Core/Portable/CommandLine/CommonCompiler.cs

@@ -159,33 +159,21 @@ internal string GetCompilerVersion()
         internal static string GetProductVersion(Type type)
         {
             string? assemblyVersion = GetInformationalVersionWithoutHash(type);
-            string? hash = GetShortCommitHash(type);
+            string? hash = type.Assembly.GetCustomAttribute<CommitHashAttribute>()?.Hash;
             return $"{assemblyVersion} ({hash})";
         }
 
-        [return: NotNullIfNotNull(nameof(hash))]
-        internal static string? ExtractShortCommitHash(string? hash)
-        {
-            // leave "<developer build>" alone, but truncate SHA to 8 characters
-            if (hash != null && hash.Length >= 8 && hash[0] != '<')
-            {
-                return hash.Substring(0, 8);
-            }
-
-            return hash;
-        }
-
         private static string? GetInformationalVersionWithoutHash(Type type)
         {
             // The attribute stores a SemVer2-formatted string: `A.B.C(-...)?(+...)?`
             // We remove the section after the + (if any is present)
             return type.Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion.Split('+')[0];
         }
 
-        private static string? GetShortCommitHash(Type type)
+        internal static string GetAssemblyLocation(Type type)
         {
-            var hash = type.Assembly.GetCustomAttribute<CommitHashAttribute>()?.Hash;
-            return ExtractShortCommitHash(hash);
+            var location = type.Assembly.Location;
+            return string.IsNullOrEmpty(location) ? "<unknown>" : location;
         }
 
         /// <summary>