Add more cases of structure initialization (#949)

* Add more cases of structure initialization

Author: kant2002

Cesium.CodeGen.Tests/CodeGenTypeTests.cs

@@ -395,6 +395,24 @@ int main() {
     Foo f = { { 1, 2 }, 32 };
     return f.a + f.b[0] + f.b[1];
 }
+");
+
+    [Fact]
+    public Task StructVariableInitialization() => DoTest(@"typedef struct Foo { int a; int b; } Foo;
+int main() {
+    int c = 1;
+    Foo f = { c, 2 };
+    return f.a + f.b;
+}
+");
+
+    [Fact]
+    public Task StructCastInitialization() => DoTest(@"typedef struct Foo { int a; int b; } Foo;
+int main() {
+    int c = 1;
+    Foo f = { (int)c, 2 };
+    return f.a + f.b;
+}
 ");
 
     [Fact]

Cesium.CodeGen.Tests/verified/CodeGenTypeTests.StructCastInitialization.verified.txt

@@ -0,0 +1,42 @@
+Module: Primary
+  Type: <Module>
+  Methods:
+    System.Int32 <Module>::main()
+      Locals:
+        System.Int32 V_0
+        Foo V_1
+        Foo V_2
+      IL_0000: ldc.i4.1
+      IL_0001: stloc.0
+      IL_0002: ldloca V_2
+      IL_0006: initobj Foo
+      IL_000c: ldloca V_2
+      IL_0010: ldloc.0
+      IL_0011: conv.i4
+      IL_0012: stfld System.Int32 Foo::a
+      IL_0017: ldloca V_2
+      IL_001b: ldc.i4.2
+      IL_001c: stfld System.Int32 Foo::b
+      IL_0021: ldloc V_2
+      IL_0025: stloc.1
+      IL_0026: ldloca.s V_1
+      IL_0028: ldfld System.Int32 Foo::a
+      IL_002d: ldloca.s V_1
+      IL_002f: ldfld System.Int32 Foo::b
+      IL_0034: add
+      IL_0035: ret
+
+    System.Int32 <Module>::<SyntheticEntrypoint>()
+      Locals:
+        System.Int32 V_0
+      IL_0000: call System.Int32 <Module>::main()
+      IL_0005: stloc.s V_0
+      IL_0007: ldloc.s V_0
+      IL_0009: call System.Void Cesium.Runtime.RuntimeHelpers::Exit(System.Int32)
+      IL_000e: ldloc.s V_0
+      IL_0010: ret
+
+  Type: Foo
+  Fields:
+    System.Int32 Foo::a
+    System.Int32 Foo::b

Cesium.CodeGen.Tests/verified/CodeGenTypeTests.StructVariableInitialization.verified.txt

@@ -0,0 +1,41 @@
+Module: Primary
+  Type: <Module>
+  Methods:
+    System.Int32 <Module>::main()
+      Locals:
+        System.Int32 V_0
+        Foo V_1
+        Foo V_2
+      IL_0000: ldc.i4.1
+      IL_0001: stloc.0
+      IL_0002: ldloca V_2
+      IL_0006: initobj Foo
+      IL_000c: ldloca V_2
+      IL_0010: ldloc.0
+      IL_0011: stfld System.Int32 Foo::a
+      IL_0016: ldloca V_2
+      IL_001a: ldc.i4.2
+      IL_001b: stfld System.Int32 Foo::b
+      IL_0020: ldloc V_2
+      IL_0024: stloc.1
+      IL_0025: ldloca.s V_1
+      IL_0027: ldfld System.Int32 Foo::a
+      IL_002c: ldloca.s V_1
+      IL_002e: ldfld System.Int32 Foo::b
+      IL_0033: add
+      IL_0034: ret
+
+    System.Int32 <Module>::<SyntheticEntrypoint>()
+      Locals:
+        System.Int32 V_0
+      IL_0000: call System.Int32 <Module>::main()
+      IL_0005: stloc.s V_0
+      IL_0007: ldloc.s V_0
+      IL_0009: call System.Void Cesium.Runtime.RuntimeHelpers::Exit(System.Int32)
+      IL_000e: ldloc.s V_0
+      IL_0010: ret
+
+  Type: Foo
+  Fields:
+    System.Int32 Foo::a
+    System.Int32 Foo::b

Cesium.CodeGen/Ir/Expressions/CompoundObjectInitializationExpression.cs

@@ -111,7 +111,7 @@ public void EmitTo(IEmitScope scope)
             if (init == null)
                 throw new CompilationException($"Retrieved null initializer!");
 
-            if (init is ConstantLiteralExpression)
+            if (init is ConstantLiteralExpression or GetValueExpression or TypeCastExpression)
             {
                 instructions.Add(Instruction.Create(OpCodes.Ldloca, newobj));
                 init.EmitTo(scope);

Cesium.IntegrationTests/structs/struct_init2.nonportable.c

@@ -0,0 +1,17 @@
+/*
+ * SPDX-FileCopyrightText: 2025 Cesium contributors <https://github.com/ForNeVeR/Cesium>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+#include <stddef.h>
+
+typedef struct Foo
+{
+    int* a;
+    int b;
+} Foo;
+int main() {
+    int c = 33;
+    Foo f = { NULL, c };
+    return (int)f.a + f.b + 9;
+}