Fix up translation of `GetDimensions()`

Fixes #122

- In cases with an explicit mip level being specified, there was a mistake in how the argument for setting the mip level in the GLSL code was constructed that led to a parse error in GLSL

- Also, that argument is a `uint` in HLSL and an `int` in GLSL, so an explicit cast was needed

- The GLSL functions here seem to require a newer GLSL (at least higher than `420`), so I had to add in a capability for builtins to specify a required GLSL version. For now I made these ones require `450`.

- Added a test case to confirm that our lowering works (for some definition of "works")

2 files changed, 47 insertions, 0 deletions

diff --git a/tests/bugs/gh-122.slang b/tests/bugs/gh-122.slang
new file mode 100644
index 000000000..1a011df37
--- /dev/null
+++ b/tests/bugs/gh-122.slang
@@ -0,0 +1,15 @@
+//TEST:CROSS_COMPILE: -profile ps_5_0 -entry main -target spirv-assembly
+
+// Ensure that `GetDimensions` with `mipCount` output works
+// on a `Texture2D`
+
+layout(binding = 1)
+Texture2D t;
+
+float4 main() : SV_Target
+{
+	uint x, y, mipCount;
+    t.GetDimensions(0, x, y, mipCount);
+
+    return float4(x, y, mipCount, 0);
+}
diff --git a/tests/bugs/gh-122.slang.glsl b/tests/bugs/gh-122.slang.glsl
new file mode 100644
index 000000000..a6f43256e
--- /dev/null
+++ b/tests/bugs/gh-122.slang.glsl
@@ -0,0 +1,32 @@
+#version 450
+//TEST_IGNORE_FILE:
+
+layout(binding = 0)
+uniform sampler SLANG_hack_samplerForTexelFetch;
+
+layout(binding = 1)
+uniform texture2D t;
+
+vec4 main_()
+{
+	uint x, y, mipCount;
+
+	x = textureSize(sampler2D(t,SLANG_hack_samplerForTexelFetch), 0).x;
+	y = textureSize(sampler2D(t,SLANG_hack_samplerForTexelFetch), 0).y;
+	mipCount = textureQueryLevels(sampler2D(t,SLANG_hack_samplerForTexelFetch));
+
+    return vec4(
+    	float(x),
+    	float(y),
+    	float(mipCount),
+    	0.0);
+}
+
+layout(location = 0)
+out vec4 SLANG_out_main_result;
+
+void main()
+{
+	vec4 main_result = main_();
+	SLANG_out_main_result = main_result;
+}