Implement default initializer list for C-Style type member (#7079)

* Implement default initializer list for C-Style type member

Close #6189.

Previsouly, for the C-Style member in a struct, if it doesn't have any initialize
expression, when we synthesize the ctor, we will not associate the
default value for the parameter corresponding to that member.

This bring some trouble that existing slang users has to add '= {}' to
every struct fields in order to make all the parameters in the synthesized ctor having
a default value, so people can still use `Struct a = {}` to create a
struct.

To make this use case convenience, we will automatically associated a
'= {}' as the default value for this case.

This PR also add support for empty initializing link-time sized vector/matrix by "= {}".
In addition, this PR also fix a bug in auto diff where we should not report error when proccessing
transpose on an empty struct.

7 files changed, 111 insertions, 25 deletions

diff --git a/tests/initializer-list/c-style-type.slang b/tests/initializer-list/c-style-type.slang
index 500bf37bb..8afa1e282 100644
--- a/tests/initializer-list/c-style-type.slang
+++ b/tests/initializer-list/c-style-type.slang
@@ -6,7 +6,7 @@ struct CLike
   int x;
   int y;
   // compiler synthesizes:
-  // __init(int x, int y);
+  // __init(int x = {}, int y = {});
 }
 
 //TEST_INPUT:ubuffer(data=[0 0 0 0 0 0], stride=4):out,name=outputBuffer
diff --git a/tests/initializer-list/default-init-c-style-member.slang b/tests/initializer-list/default-init-c-style-member.slang
new file mode 100644
index 000000000..41dba5bd0
--- /dev/null
+++ b/tests/initializer-list/default-init-c-style-member.slang
@@ -0,0 +1,62 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUFFER):-shaderobj -vk
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUFFER):-shaderobj
+
+struct NonCStyle
+{
+  int x;
+  __init(int x)
+  {
+    this.x = x;
+  }
+}
+
+struct CLike
+{
+  NonCStyle nonCStyleMember;
+  int x;
+  int y;
+  // compiler synthesizes:
+  // __init(NonCStyle nonCStyleMember, int x = {}, int y = {});
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<int> outputBuffer;
+void test()
+{
+  // case 1: initialized with synthesized ctor call, but CLike::x and CLike::y are default initialized
+  // and `c1` is now `{1, 0, 0}`.
+  CLike c1 = {NonCStyle(1)};
+
+  // case 2: initialized with synthesized ctor call, CLike::y are default initialized
+  CLike c2 = {NonCStyle(1), 2};
+
+  // case 3: initialized with synthesized ctor call
+  CLike c3 = {NonCStyle(1), 2, 3};
+
+  outputBuffer[0] = c1.nonCStyleMember.x;
+  // BUFFER: 1
+  outputBuffer[1] = c1.x;
+  // BUFFER-NEXT: 0
+  outputBuffer[2] = c1.y;
+  // BUFFER-NEXT: 0
+
+  outputBuffer[3] = c2.nonCStyleMember.x;
+  // BUFFER-NEXT: 1
+  outputBuffer[4] = c2.x;
+  // BUFFER-NEXT: 2
+  outputBuffer[5] = c2.y;
+  // BUFFER-NEXT: 0
+
+  outputBuffer[6] = c3.nonCStyleMember.x;
+  // BUFFER-NEXT: 1
+  outputBuffer[7] = c3.x;
+  // BUFFER-NEXT: 2
+  outputBuffer[8] = c3.y;
+  // BUFFER-NEXT: 3
+}
+
+[shader("compute")]
+void computeMain()
+{
+    test();
+}
diff --git a/tests/initializer-list/generic-array-init.slang b/tests/initializer-list/generic-array-init.slang
index 4257e2972..83c14ebd2 100644
--- a/tests/initializer-list/generic-array-init.slang
+++ b/tests/initializer-list/generic-array-init.slang
@@ -2,7 +2,7 @@
 //TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUFFER):-shaderobj -mtl
 //TEST(compute):COMPARE_COMPUTE(filecheck-buffer=BUFFER):-cpu -compute -entry computeMain
 
-//TEST_INPUT:ubuffer(data=[9 9 9 9], stride=4):out,name=outputBuffer
+//TEST_INPUT:ubuffer(data=[9 9 9 9 9 9 9 9 9 9 9 9], stride=4):out,name=outputBuffer
 RWStructuredBuffer<int> outputBuffer;
 
 void test<let TSize : uint>()
@@ -18,6 +18,28 @@ void test<let TSize : uint>()
     outputBuffer[2] = array[2];
     // BUFFER-NEXT: 3
     outputBuffer[3] = array.getCount();
+
+    vector<int, TSize> vec = {};
+
+    // BUFFER-NEXT: 0
+    outputBuffer[4] = vec[0];
+    // BUFFER-NEXT: 0
+    outputBuffer[5] = vec[1];
+    // BUFFER-NEXT: 0
+    outputBuffer[6] = vec[2];
+    // BUFFER-NEXT: 3
+    outputBuffer[7] = vec.getCount();
+
+    matrix<float, TSize, TSize-1> mat = {};
+
+    // BUFFER-NEXT: 0
+    outputBuffer[8] = (int)mat[0][0];
+    // BUFFER-NEXT: 0
+    outputBuffer[9] = (int)mat[1][1];
+    // BUFFER-NEXT: 0
+    outputBuffer[10] = (int)mat[2][1];
+    // BUFFER-NEXT: 3
+    outputBuffer[11] = mat.getCount();  // this is a bad name, getCount() is actually get the number of row.
 }
 
 [shader("compute")]
@@ -25,4 +47,4 @@ void test<let TSize : uint>()
 void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
 {
     test<3>();
-} 
+}
diff --git a/tests/initializer-list/partial-init.slang b/tests/initializer-list/partial-init.slang
index 55f3816fb..a4739f041 100644
--- a/tests/initializer-list/partial-init.slang
+++ b/tests/initializer-list/partial-init.slang
@@ -8,15 +8,15 @@ struct PartialInit {
   int x;
   int y = 1;
   // compiler synthesizes:
-  // __init(int x, int y = 1);
+  // __init(int x = {}, int y = 1);
 }
 
 struct PartialInit2 {
   int x = 1;
   int y;
-  // __init(int x, int y);
+  // __init(int x, int y = {});
 }
-//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0], stride=4):out,name=outputBuffer
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
 RWStructuredBuffer<int> outputBuffer;
 void test()
 {
@@ -38,6 +38,18 @@ void test()
   outputBuffer[4] = p3.x;
   // BUFFER-NEXT: 5
   outputBuffer[5] = p3.y;
+
+  PartialInit p4 = {}; // calls `__init`, result is {0, 1}
+  // BUFFER-NEXT: 0
+  outputBuffer[6] = p4.x;
+  // BUFFER-NEXT: 1
+  outputBuffer[7] = p4.y;
+
+  PartialInit2 p5 = {}; // calls `__init`, result is {1, 0}
+  // BUFFER-NEXT: 1
+  outputBuffer[8] = p5.x;
+  // BUFFER-NEXT: 0
+  outputBuffer[9] = p5.y;
 }
 
 [shader("compute")]
diff --git a/tests/initializer-list/struct-visibility-diagnostic-1.slang b/tests/initializer-list/struct-visibility-diagnostic-1.slang
index ab11933ae..1670860ad 100644
--- a/tests/initializer-list/struct-visibility-diagnostic-1.slang
+++ b/tests/initializer-list/struct-visibility-diagnostic-1.slang
@@ -4,12 +4,8 @@ public struct Visibility
 {
   internal int x;
   public int y = 0;
-  // the compiler does not synthesize any ctor.
-  // the compiler will try to synthesize:
-  //     public __init(int y);
-  // but then it will find that `x` cannot be initialized.
-  // so this synthesis will fail and no ctor will be added
-  // to the type.
+  // will synthesize a constructor
+  // __init(int y = 0)
 }
 
 void test()
diff --git a/tests/initializer-list/struct-visibility-diagnostic-2.slang b/tests/initializer-list/struct-visibility-diagnostic-2.slang
index a3255de5e..b9e92555b 100644
--- a/tests/initializer-list/struct-visibility-diagnostic-2.slang
+++ b/tests/initializer-list/struct-visibility-diagnostic-2.slang
@@ -4,12 +4,8 @@ public struct Visibility
 {
   internal int x;
   public int y = 5;
-  // the compiler does not synthesize any ctor.
-  // the compiler will try to synthesize:
-  //     public __init(int y);
-  // but then it will find that `x` cannot be initialized.
-  // so this synthesis will fail and no ctor will be added
-  // to the type.
+  // will synthesize a constructor
+  // __init(int y = 0)
 }
 
 void test()
diff --git a/tests/initializer-list/struct-visibility-diagnostic-3.slang b/tests/initializer-list/struct-visibility-diagnostic-3.slang
index 75ac5919d..e36bd4e4e 100644
--- a/tests/initializer-list/struct-visibility-diagnostic-3.slang
+++ b/tests/initializer-list/struct-visibility-diagnostic-3.slang
@@ -1,15 +1,13 @@
 //DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
 
+public struct NonCStyle
+{}
 public struct Visibility
 {
   internal int x;
-  public int y;
-  // the compiler does not synthesize any ctor.
-  // the compiler will try to synthesize:
-  //     public __init(int y);
-  // but then it will find that `x` cannot be initialized.
-  // so this synthesis will fail and no ctor will be added
-  // to the type.
+  public int[] y; // define a unsized array here on purpose so that the ctor will not associate it with a '{}' initializer
+  // will synthesize a constructor
+  // __init(int[] y)
 }
 
 void test()