Convert integers to char literals in comparisons with char operands.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.cs

@@ -96,6 +96,11 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			return value;
 		}
 
+		public bool IsUpperCaseA(char a)
+		{
+			return a == 'A';
+		}
+		
 		public void Int32_Local_Add(int i)
 		{
 			i++;

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.il

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly '140sffme'
+.assembly rtuqxf3v
 {
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
   .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
@@ -20,15 +20,15 @@
   .hash algorithm 0x00008004
   .ver 0:0:0:0
 }
-.module '140sffme.dll'
+.module rtuqxf3v.dll
-// MVID: {4B912E9D-0D9D-4F78-B2A7-5F041A58B7CC}
+// MVID: {0891498F-C2CF-4474-B2F7-31DC8C6C47C7}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x00850000
+// Image base: 0x00DF0000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -260,6 +260,23 @@
     IL_0006:  ret
   } // end of method CompoundAssignmentTest::GetValue
 
+  .method public hidebysig instance bool 
+          IsUpperCaseA(char a) cil managed
+  {
+    // Code size       11 (0xb)
+    .maxstack  2
+    .locals init (bool V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  ldc.i4.s   65
+    IL_0004:  ceq
+    IL_0006:  stloc.0
+    IL_0007:  br.s       IL_0009
+
+    IL_0009:  ldloc.0
+    IL_000a:  ret
+  } // end of method CompoundAssignmentTest::IsUpperCaseA
+
   .method public hidebysig instance void 
           Int32_Local_Add(int32 i) cil managed
   {
@@ -864,4 +881,4 @@
 // =============================================================
 
 // *********** DISASSEMBLY COMPLETE ***********************
-// WARNING: Created Win32 resource file ../../Tests/TestCases/Pretty\CompoundAssignmentTest.res
+// WARNING: Created Win32 resource file ../../../../ICSharpCode.Decompiler.Tests/TestCases/Pretty\CompoundAssignmentTest.res

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.il

@@ -10,7 +10,7 @@
   .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
   .ver 4:0:0:0
 }
-.assembly a1plok3m
+.assembly mjdn04ya
 {
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
   .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
@@ -20,15 +20,15 @@
   .hash algorithm 0x00008004
   .ver 0:0:0:0
 }
-.module a1plok3m.dll
+.module mjdn04ya.dll
-// MVID: {7BD8D57D-A1D7-460B-8B05-A3F6005A275C}
+// MVID: {D8AF2CB3-EE41-4B93-96CE-1FD07E5E4237}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x01350000
+// Image base: 0x01640000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -212,6 +212,17 @@
     IL_0001:  ret
   } // end of method CompoundAssignmentTest::GetValue
 
+  .method public hidebysig instance bool 
+          IsUpperCaseA(char a) cil managed
+  {
+    // Code size       6 (0x6)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  ldc.i4.s   65
+    IL_0003:  ceq
+    IL_0005:  ret
+  } // end of method CompoundAssignmentTest::IsUpperCaseA
+
   .method public hidebysig instance void 
           Int32_Local_Add(int32 i) cil managed
   {
@@ -723,4 +734,4 @@
 // =============================================================
 
 // *********** DISASSEMBLY COMPLETE ***********************
-// WARNING: Created Win32 resource file ../../Tests/TestCases/Pretty\CompoundAssignmentTest.opt.res
+// WARNING: Created Win32 resource file ../../../../ICSharpCode.Decompiler.Tests/TestCases/Pretty\CompoundAssignmentTest.opt.res

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.opt.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CompoundAssignmentTest.dll
-// MVID: {4291E75E-F92B-4A69-AD59-40A9D8C6DF95}
+// MVID: {0CCA0C51-2F8D-424C-BDE8-57699BE33BC6}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x00F40000
+// Image base: 0x00900000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -216,6 +216,17 @@
     IL_0001:  ret
   } // end of method CompoundAssignmentTest::GetValue
 
+  .method public hidebysig instance bool 
+          IsUpperCaseA(char a) cil managed
+  {
+    // Code size       6 (0x6)
+    .maxstack  8
+    IL_0000:  ldarg.1
+    IL_0001:  ldc.i4.s   65
+    IL_0003:  ceq
+    IL_0005:  ret
+  } // end of method CompoundAssignmentTest::IsUpperCaseA
+
   .method public hidebysig instance void 
           Int32_Local_Add(int32 i) cil managed
   {

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CompoundAssignmentTest.dll
-// MVID: {FF19A157-76FD-4795-BA24-7C956CED48C1}
+// MVID: {572A9208-925A-4E92-9D86-8EC36FE271FC}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x00DA0000
+// Image base: 0x00AF0000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -257,6 +257,23 @@
     IL_0006:  ret
   } // end of method CompoundAssignmentTest::GetValue
 
+  .method public hidebysig instance bool 
+          IsUpperCaseA(char a) cil managed
+  {
+    // Code size       11 (0xb)
+    .maxstack  2
+    .locals init (bool V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.1
+    IL_0002:  ldc.i4.s   65
+    IL_0004:  ceq
+    IL_0006:  stloc.0
+    IL_0007:  br.s       IL_0009
+
+    IL_0009:  ldloc.0
+    IL_000a:  ret
+  } // end of method CompoundAssignmentTest::IsUpperCaseA
+
   .method public hidebysig instance void 
           Int32_Local_Add(int32 i) cil managed
   {

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -466,6 +466,13 @@ namespace ICSharpCode.Decompiler.CSharp
 				}
 			}
 
+			// Special case comparisons with char literals
+			if (left.Type.IsKnownType(KnownTypeCode.Char) && MightBeCharLiteral(right.ResolveResult)) {
+				right = right.ConvertTo(left.Type, this);
+			} else if (right.Type.IsKnownType(KnownTypeCode.Char) && MightBeCharLiteral(left.ResolveResult)) {
+				left = left.ConvertTo(right.Type, this);
+			}
+			
 			var rr = resolver.ResolveBinaryOperator(inst.Kind.ToBinaryOperatorType(), left.ResolveResult, right.ResolveResult)
 				as OperatorResolveResult;
 			if (rr == null || rr.IsError || rr.UserDefinedOperatorMethod != null
@@ -501,6 +508,12 @@ namespace ICSharpCode.Decompiler.CSharp
 				.WithRR(rr);
 		}
 
+		bool MightBeCharLiteral(ResolveResult rr)
+		{
+			return rr.IsCompileTimeConstant && rr.ConstantValue is int val
+				&& val >= char.MinValue && val <= char.MaxValue;
+		}
+		
 		/// <summary>
 		/// Handle Comp instruction, operators other than equality/inequality.
 		/// </summary>