Fix a bug in default ctor synthesizing (#6527)

* Fix a bug in default ctor synthesizing

- This is fix for the implementation bug, when a struct has explicit ctor
  we should not synthesize the default ctor anymore.

- When invoke the synthesized ctor converted from initializer list, we should
  check if the struct is a c-style type if it struct has no synthesized ctor. In this
  case we should report error because it's invalid to use initializer list here.

- The only exception is the unsized array, we still have to fall back to use the
  legacy initializer list logic to initialize the unsized array until we formalize a
  proper solution.

- update test.

4 files changed, 63 insertions, 25 deletions

diff --git a/tests/initializer-list/explicit-ctor-diagnostic.slang b/tests/initializer-list/explicit-ctor-diagnostic.slang
index a9d0e9858..6ce65c016 100644
--- a/tests/initializer-list/explicit-ctor-diagnostic.slang
+++ b/tests/initializer-list/explicit-ctor-diagnostic.slang
@@ -16,4 +16,7 @@ void test()
 {
    // CHECK: error 39999: too many arguments to call (got 2, expected 1)
    ExplicitCtor e = {1, 2}; // error, no ctor matches initializer list.
+
+   // CHECK: error 39999: not enough arguments to call (got 0, expected 1)
+   ExplicitCtor e1 = {};
 }
diff --git a/tests/initializer-list/struct-inherit-diagnostics.slang b/tests/initializer-list/struct-inherit-diagnostics.slang
new file mode 100644
index 000000000..247431570
--- /dev/null
+++ b/tests/initializer-list/struct-inherit-diagnostics.slang
@@ -0,0 +1,39 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+struct DefaultStruct_base
+{
+    int data0;
+    __init()
+    {
+        data0 = 2;
+    }
+};
+
+struct DefaultStruct1 : DefaultStruct_base
+{
+    int data1 = 1;
+};
+
+struct DefaultStruct2 : DefaultStruct_base
+{
+
+};
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    //CHECK: error 30504: cannot use initializer list for type 'DefaultStruct1'
+    DefaultStruct1 s1 = {};
+
+    //CHECK: error 30504: cannot use initializer list for type 'DefaultStruct1'
+    DefaultStruct1 s2 = {1};
+
+    //CHECK: error 30504: cannot use initializer list for type 'DefaultStruct1'
+    DefaultStruct1 s3 = {1, 2};
+
+    //CHECK: error 30504: cannot use initializer list for type 'DefaultStruct2'
+    DefaultStruct2 s4 = {};
+
+    //CHECK: error 30504: cannot use initializer list for type 'DefaultStruct2'
+    DefaultStruct2 s5 = {1};
+}
diff --git a/tests/language-feature/struct-field-initializers/struct-field-initializer-inherited.slang b/tests/initializer-list/struct-inherit.slang
index 954a1edbe..71487a74f 100644
--- a/tests/language-feature/struct-field-initializers/struct-field-initializer-inherited.slang
+++ b/tests/initializer-list/struct-inherit.slang
@@ -16,51 +16,42 @@ struct DefaultStruct_base
 
     __init()
     {
-        data1 = 1;
+        data0 = 2;
+        data1 = 3;
     }
 };
+
 struct DefaultStruct1 : DefaultStruct_base
 {
     int data2 = 1;
-};
-struct DefaultStruct2 : DefaultStruct_base
-{
-    int data2 = 1;
     __init()
     {
-        if (data0 != 1)
+        if (data0 == 2)
         {
-            data2 = 0;
+            data2 = 4;
         }
     }
 };
-struct DefaultStruct3 : DefaultStruct_base
+
+struct DefaultStruct2 : DefaultStruct_base
 {
     __init()
     {
     }
 };
-struct DefaultStruct4 : DefaultStruct_base
-{
-};
+
 [numthreads(1, 1, 1)]
 void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
 {
-    DefaultStruct1 s1 = {};
+    DefaultStruct1 s1;
     DefaultStruct2 s2;
-    DefaultStruct3 s3;
-    DefaultStruct4 s4 = {};
+
     // BUF: 1
     outputBuffer[0] = true
-        && s1.data0 == 1
-        && s1.data1 == 1
-        && s1.data2 == 1
-        && s2.data0 == 1
-        && s2.data1 == 1
-        && s2.data2 == 1
-        && s3.data0 == 1
-        && s3.data1 == 1
-        && s4.data0 == 1
-        && s4.data1 == 1
+        && s1.data0 == 2
+        && s1.data1 == 3
+        && s1.data2 == 4
+        && s2.data0 == 2
+        && s2.data1 == 3
         ;
 }
diff --git a/tests/language-feature/interfaces/default-construct-conformance.slang b/tests/language-feature/interfaces/default-construct-conformance.slang
index 4a6aed869..b68dc8a4c 100644
--- a/tests/language-feature/interfaces/default-construct-conformance.slang
+++ b/tests/language-feature/interfaces/default-construct-conformance.slang
@@ -33,6 +33,11 @@ struct TestAny : ITest
         value = v;
     }
 
+    __init()
+    {
+        value = 0;
+    }
+
     uint getValue() { return value; }
 }
 
@@ -183,4 +188,4 @@ void testMain(uint3 threadID: SV_DispatchThreadID)
     }
 
     expected[outputIdx++] = uint(-1);
-}
\ No newline at end of file
+}