Add CompositeFormat.MinimumArgumentCount and remove TryParse (#85348)

* Add CompositeFormat.MinimumArgumentCount

* Remove CompositeFormat.TryParse

It encourages bad patterns of consumption.

src/libraries/System.Private.CoreLib/src/System/Text/CompositeFormat.cs

@@ -85,31 +85,13 @@ public static CompositeFormat Parse([StringSyntax(StringSyntaxAttribute.Composit
             return new CompositeFormat(format, segments.ToArray());
         }
 
-        /// <summary>Try to parse the composite format string <paramref name="format"/>.</summary>
-        /// <param name="format">The string to parse.</param>
-        /// <param name="compositeFormat">The parsed <see cref="CompositeFormat"/> if parsing was successful; otherwise, null.</param>
-        /// <returns><see langword="true"/> the <paramref name="format"/> can be parsed successfully; otherwise, <see langword="false"/>.</returns>
-        public static bool TryParse([StringSyntax(StringSyntaxAttribute.CompositeFormat)] string? format, [NotNullWhen(true)] out CompositeFormat? compositeFormat)
-        {
-            if (format is not null)
-            {
-                var segments = new List<(string? Literal, int ArgIndex, int Alignment, string? Format)>();
-                int failureOffset = default;
-                ExceptionResource failureReason = default;
-                if (TryParseLiterals(format, segments, ref failureOffset, ref failureReason))
-                {
-                    compositeFormat = new CompositeFormat(format, segments.ToArray());
-                    return true;
-                }
-            }
-
-            compositeFormat = null;
-            return false;
-        }
-
         /// <summary>Gets the original composite format string used to create this <see cref="CompositeFormat"/> instance.</summary>
         public string Format { get; }
 
+        /// <summary>Gets the minimum number of arguments that must be passed to a formatting operation using this <see cref="CompositeFormat"/>.</summary>
+        /// <remarks>It's permissible to supply more arguments than this value, but it's an error to pass fewer.</remarks>
+        public int MinimumArgumentCount => _argsRequired;
+
         /// <summary>Throws an exception if the specified number of arguments is fewer than the number required.</summary>
         /// <param name="numArgs">The number of arguments provided by the caller.</param>
         /// <exception cref="FormatException">An insufficient number of arguments were provided.</exception>

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -14194,8 +14194,8 @@ public sealed class CompositeFormat
     {
         internal CompositeFormat() { }
         public static System.Text.CompositeFormat Parse([System.Diagnostics.CodeAnalysis.StringSyntaxAttribute("CompositeFormat")] string format) { throw null; }
-        public static bool TryParse([System.Diagnostics.CodeAnalysis.StringSyntaxAttribute("CompositeFormat")] string format, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out System.Text.CompositeFormat? compositeFormat) { throw null; }
         public string Format { get { throw null; } }
+        public int MinimumArgumentCount { get { throw null; } }
     }
     public abstract partial class Decoder
     {

src/libraries/System.Runtime/tests/System/Text/CompositeFormatTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Linq;
 using Xunit;
 
 namespace System.Text.Tests
@@ -13,9 +14,6 @@ public void NullArgument_Throws()
         {
             AssertExtensions.Throws<ArgumentNullException>("format", () => CompositeFormat.Parse(null));
 
-            Assert.False(CompositeFormat.TryParse(null, out CompositeFormat? compositeFormat));
-            Assert.Null(compositeFormat);
-
             AssertExtensions.Throws<ArgumentNullException>("format", () => string.Format(null, (CompositeFormat)null, 0));
             AssertExtensions.Throws<ArgumentNullException>("format", () => string.Format(null, (CompositeFormat)null, 0, 0));
             AssertExtensions.Throws<ArgumentNullException>("format", () => string.Format(null, (CompositeFormat)null, 0, 0, 0));
@@ -55,6 +53,30 @@ public static void DebuggerDisplay_ShowsFormat()
             Assert.Equal($"\"{format}\"", DebuggerAttributes.ValidateDebuggerDisplayReferences(cf));
         }
 
+        [Theory]
+        [InlineData("", 0)]
+        [InlineData("testing 123", 0)]
+        [InlineData("testing {{123}}", 0)]
+        [InlineData("{0}", 1)]
+        [InlineData("{0} {1}", 2)]
+        [InlineData("{2}", 3)]
+        [InlineData("{2} {0}", 3)]
+        [InlineData("{1} {34} {3}", 35)]
+        public static void MinimumArgumentCount_MatchesExpectedValue(string format, int expected)
+        {
+            CompositeFormat cf = CompositeFormat.Parse(format);
+
+            Assert.Equal(expected, cf.MinimumArgumentCount);
+
+            string s = string.Format(null, cf, Enumerable.Repeat((object)"arg", expected).ToArray());
+            Assert.NotNull(s);
+
+            if (expected != 0)
+            {
+                Assert.Throws<FormatException>(() => string.Format(null, cf, Enumerable.Repeat((object)"arg", expected - 1).ToArray()));
+            }
+        }
+
         [Theory]
         [MemberData(nameof(System.Tests.StringTests.Format_Valid_TestData), MemberType = typeof(System.Tests.StringTests))]
         public static void StringFormat_Valid(IFormatProvider provider, string format, object[] values, string expected)
@@ -63,10 +85,6 @@ public static void StringFormat_Valid(IFormatProvider provider, string format, o
             Assert.NotNull(cf);
             Assert.Same(format, cf.Format);
 
-            Assert.True(CompositeFormat.TryParse(format, out CompositeFormat? cf2));
-            Assert.NotNull(cf2);
-            Assert.Same(format, cf2.Format);
-
             Assert.Equal(expected, string.Format(provider, cf, values));
 
             Assert.Equal(expected, string.Format(provider, cf, (ReadOnlySpan<object?>)values));
@@ -95,10 +113,6 @@ public static void StringBuilderAppendFormat_Valid(IFormatProvider provider, str
             Assert.NotNull(cf);
             Assert.Same(format, cf.Format);
 
-            Assert.True(CompositeFormat.TryParse(format, out CompositeFormat? cf2));
-            Assert.NotNull(cf2);
-            Assert.Same(format, cf2.Format);
-
             var sb = new StringBuilder();
 
             Assert.Same(sb, sb.AppendFormat(provider, cf, values));
@@ -135,10 +149,6 @@ public static void MemoryExtensionsTryWrite_Valid(IFormatProvider provider, stri
             Assert.NotNull(cf);
             Assert.Same(format, cf.Format);
 
-            Assert.True(CompositeFormat.TryParse(format, out CompositeFormat? cf2));
-            Assert.NotNull(cf2);
-            Assert.Same(format, cf2.Format);
-
             char[] dest = new char[expected.Length];
             int charsWritten;
 
@@ -189,9 +199,6 @@ public static void Parse_Invalid_FormatExceptionFromFormat(IFormatProvider provi
             _ = args;
 
             Assert.Throws<FormatException>(() => CompositeFormat.Parse(format));
-
-            Assert.False(CompositeFormat.TryParse(format, out CompositeFormat? compositeFormat));
-            Assert.Null(compositeFormat);
         }
 
         [Theory]