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")

8 files changed, 158 insertions, 60 deletions

diff --git a/.gitignore b/.gitignore
index 9267cfca3..26a5f0506 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,15 +8,17 @@
 bin/
 intermediate/
 
-# files generated by test runner
+# Files generated by test runner.
+#
+# Note: in some cases a `.expected` file needs to be checked in, but
+# trying to exhaustively enumerate those cases is hard with the
+# way the tests are currently sorted.
+
 *.actual
 *.expected
-!*.slang.expected
-!*.slang.*.expected
 *.expected.png
 *.actual.png
-tests/render/*.expected
-tests/cross-compile/*.expected
 
-# files generated by other shader compilers
+# Files generated by other shader compilers
+
 *.spv
diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 8660b5f93..2f009bb81 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -74,6 +74,31 @@ struct EmitContext
 
 //
 
+void requireGLSLVersion(
+    EntryPointRequest*  entryPoint,
+    ProfileVersion      version)
+{
+    auto profile = entryPoint->profile;
+    auto currentVersion = profile.GetVersion();
+    if (profile.getFamily() == ProfileFamily::GLSL)
+    {
+        // Check if this profile is newer
+        if ((UInt)version > (UInt)profile.GetVersion())
+        {
+            profile.setVersion(version);
+            entryPoint->profile = profile;
+        }
+    }
+    else
+    {
+        // Non-GLSL target? Set it to a GLSL one.
+        profile.setVersion(version);
+        entryPoint->profile = profile;
+    }
+}
+
+//
+
 static String getStringOrIdentifierTokenValue(
     Token const& token)
 {
@@ -1647,6 +1672,39 @@ struct EmitVisitor
         context->shared->glslExtensionsRequired.Add(name);
     }
 
+    void requireGLSLVersion(ProfileVersion version)
+    {
+        if (context->shared->target != CodeGenTarget::GLSL)
+            return;
+
+        auto entryPoint = context->shared->entryPoint;
+        Slang::requireGLSLVersion(entryPoint, version);
+    }
+
+    void requireGLSLVersion(int version)
+    {
+        switch (version)
+        {
+    #define CASE(NUMBER) \
+        case NUMBER: requireGLSLVersion(ProfileVersion::GLSL_##NUMBER); break
+
+        CASE(110);
+        CASE(120);
+        CASE(130);
+        CASE(140);
+        CASE(150);
+        CASE(330);
+        CASE(400);
+        CASE(410);
+        CASE(420);
+        CASE(430);
+        CASE(440);
+        CASE(450);
+
+    #undef CASE
+        }
+    }
+
     void visitInvokeExpressionSyntaxNode(
         RefPtr<InvokeExpressionSyntaxNode>  callExpr,
         ExprEmitArg const& arg)
@@ -1768,6 +1826,13 @@ struct EmitVisitor
                         // If so, we had better request the extension.
                         requireGLSLExtension(requiredGLSLExtensionModifier->extensionNameToken.Content);
                     }
+
+                    // Does this intrinsic requie a particular GLSL extension that wouldn't be available by default?
+                    if (auto requiredGLSLVersionModifier = funcDecl->FindModifier<RequiredGLSLVersionModifier>())
+                    {
+                        // If so, we had better request the extension.
+                        requireGLSLVersion((int) getIntegerLiteralValue(requiredGLSLVersionModifier->versionNumberToken));
+                    }
                 }
 
 
@@ -3705,47 +3770,22 @@ String emitEntryPoint(
     auto lowered = lowerEntryPoint(entryPoint, programLayout, target);
     sharedContext.program = lowered.program;
 
+    // Note that we emit the main body code of the program *before*
+    // we emit any leading preprocessor directives for GLSL.
+    // This is to give the emit logic a change to make last-minute
+    // adjustments like changing the required GLSL version.
+    //
+    // TODO: All such adjustments would be better handled during
+    // lowering, but that requires having a semantic rather than
+    // textual format for the HLSL->GLSL mapping.
+    visitor.EmitDeclsInContainer(lowered.program.Ptr());
+    String code = sharedContext.sb.ProduceString();
+    sharedContext.sb.Clear();
 
     // There may be global-scope modifiers that we should emit now
     visitor.emitGLSLPreprocessorDirectives(translationUnitSyntax);
-
     String prefix = sharedContext.sb.ProduceString();
-    sharedContext.sb.Clear();
 
-    switch(target)
-    {
-    case CodeGenTarget::GLSL:
-        {
-            // TODO(tfoley): Need a plan for how to enable/disable these as needed...
-//            Emit(context, "#extension GL_GOOGLE_cpp_style_line_directive : require\n");
-        }
-        break;
-
-    default:
-        break;
-    }
-
-
-    visitor.EmitDeclsInContainer(lowered.program.Ptr());
-
-#if 0
-    if( isRewrite )
-    {
-        // In rewrite mode, we will just emit the text of the translation unit as given,
-        // and not pay attention to the specific entry point that was requested.
-        //
-        // It is a user error to request GLSL output and have an entry point name
-        // other than `main`.
-        EmitDeclsInContainerUsingLayout(&context, translationUnitSyntax, globalStructLayout);
-    }
-    else
-    {
-        // We are being asked to emit a single entry point in "full" mode.
-        emitEntryPoint(&context, entryPoint);
-    }
-#endif
-
-    String code = sharedContext.sb.ProduceString();
 
     StringBuilder finalResultBuilder;
     finalResultBuilder << prefix;
diff --git a/source/slang/lower.cpp b/source/slang/lower.cpp
index 127ef75ca..c61003bc6 100644
--- a/source/slang/lower.cpp
+++ b/source/slang/lower.cpp
@@ -291,6 +291,10 @@ static void attachLayout(
     addModifier(syntax, modifier);
 }
 
+void requireGLSLVersion(
+    EntryPointRequest*  entryPoint,
+    ProfileVersion      version);
+
 struct LoweringVisitor
     : ExprVisitor<LoweringVisitor, RefPtr<ExpressionSyntaxNode>>
     , StmtVisitor<LoweringVisitor, void>
@@ -2958,23 +2962,7 @@ struct LoweringVisitor
             return;
 
         auto entryPoint = shared->entryPointRequest;
-        auto profile = entryPoint->profile;
-        auto currentVersion = profile.GetVersion();
-        if (profile.getFamily() == ProfileFamily::GLSL)
-        {
-            // Check if this profile is newer
-            if ((UInt)version > (UInt)profile.GetVersion())
-            {
-                profile.setVersion(version);
-                entryPoint->profile = profile;
-            }
-        }
-        else
-        {
-            // Non-GLSL target? Set it to a GLSL one.
-            profile.setVersion(version);
-            entryPoint->profile = profile;
-        }
+        Slang::requireGLSLVersion(entryPoint, version);
     }
 
     RefPtr<ExpressionSyntaxNode> lowerSimpleShaderParameterToGLSLGlobal(
diff --git a/source/slang/modifier-defs.h b/source/slang/modifier-defs.h
index fadc68695..89f2096e4 100644
--- a/source/slang/modifier-defs.h
+++ b/source/slang/modifier-defs.h
@@ -59,6 +59,12 @@ SYNTAX_CLASS(RequiredGLSLExtensionModifier, Modifier)
     FIELD(Token, extensionNameToken)
 END_SYNTAX_CLASS()
 
+// A modifier to tag something as an intrinsic that requires
+// a certain GLSL version to be enabled when used
+SYNTAX_CLASS(RequiredGLSLVersionModifier, Modifier)
+    FIELD(Token, versionNumberToken)
+END_SYNTAX_CLASS()
+
 SIMPLE_SYNTAX_CLASS(InOutModifier, OutModifier)
 
 // This is a special sentinel modifier that gets added
diff --git a/source/slang/parser.cpp b/source/slang/parser.cpp
index 50205ff29..a624c58c5 100644
--- a/source/slang/parser.cpp
+++ b/source/slang/parser.cpp
@@ -729,6 +729,19 @@ namespace Slang
                 AddModifier(&modifierLink, modifier);
             }
 
+            else if (AdvanceIf(parser, "__glsl_version"))
+            {
+                auto modifier = new RequiredGLSLVersionModifier();
+                modifier->Position = loc;
+
+                parser->ReadToken(TokenType::LParent);
+                modifier->versionNumberToken = parser->ReadToken(TokenType::IntegerLiteral);
+                parser->ReadToken(TokenType::RParent);
+
+                AddModifier(&modifierLink, modifier);
+            }
+
+
             else if (AdvanceIf(parser, "layout"))
             {
                 parser->ReadToken(TokenType::LParent);
diff --git a/source/slang/slang-stdlib.cpp b/source/slang/slang-stdlib.cpp
index a62db693c..7850b0ce0 100644
--- a/source/slang/slang-stdlib.cpp
+++ b/source/slang/slang-stdlib.cpp
@@ -1417,6 +1417,7 @@ namespace Slang
                     for(int includeMipInfo = 0; includeMipInfo < 2; ++includeMipInfo)
                     {
                         {
+                            sb << "__glsl_version(450)\n";
                             sb << "__intrinsic(glsl, \"(";
 
                             int aa = 0;
@@ -1424,8 +1425,9 @@ namespace Slang
                             if (includeMipInfo)
                             {
                                 int mipLevelArg = aa++;
-                                lodStr.append("$");
+                                lodStr = "int($";
                                 lodStr.append(mipLevelArg);
+                                lodStr.append(")");
                             }
 
                             int cc = 0;
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;
+}