Delete Single-Plane External Texture Transform

The multiplanar external texture transform has been integrated into
Dawn, which means we have no use for the single plane transform - so it
should be deleted.

Bug: dawn:1082
Change-Id: Id8977d03839b76c90ae6e70400d048c13fbe85f4
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80120
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Brandon1 Jones <brandon1.jones@intel.com>
diff --git a/src/tint/writer/glsl/generator_impl.cc b/src/tint/writer/glsl/generator_impl.cc
index 01c1d88..58e564a 100644
--- a/src/tint/writer/glsl/generator_impl.cc
+++ b/src/tint/writer/glsl/generator_impl.cc
@@ -2552,6 +2552,12 @@
   } else if (auto* str = type->As<sem::Struct>()) {
     out << StructName(str);
   } else if (auto* tex = type->As<sem::Texture>()) {
+    if (tex->Is<sem::ExternalTexture>()) {
+      TINT_ICE(Writer, diagnostics_)
+          << "Multiplanar external texture transform was not run.";
+      return false;
+    }
+
     auto* storage = tex->As<sem::StorageTexture>();
     auto* ms = tex->As<sem::MultisampledTexture>();
     auto* depth_ms = tex->As<sem::DepthMultisampledTexture>();
diff --git a/src/tint/writer/hlsl/generator_impl.cc b/src/tint/writer/hlsl/generator_impl.cc
index 79664ae..0ddd070 100644
--- a/src/tint/writer/hlsl/generator_impl.cc
+++ b/src/tint/writer/hlsl/generator_impl.cc
@@ -52,7 +52,6 @@
 #include "src/tint/transform/calculate_array_length.h"
 #include "src/tint/transform/canonicalize_entry_point_io.h"
 #include "src/tint/transform/decompose_memory_access.h"
-#include "src/tint/transform/external_texture_transform.h"
 #include "src/tint/transform/fold_trivial_single_use_lets.h"
 #include "src/tint/transform/localize_struct_array_assignment.h"
 #include "src/tint/transform/loop_to_for_loop.h"
@@ -206,7 +205,6 @@
   // DecomposeMemoryAccess special-cases the arrayLength() intrinsic, which
   // will be transformed by CalculateArrayLength
   manager.Add<transform::CalculateArrayLength>();
-  manager.Add<transform::ExternalTextureTransform>();
   manager.Add<transform::PromoteInitializersToConstVar>();
 
   manager.Add<transform::PadArrayElements>();
@@ -3645,6 +3643,12 @@
         return true;
       },
       [&](const sem::Texture* tex) {
+        if (tex->Is<sem::ExternalTexture>()) {
+          TINT_ICE(Writer, diagnostics_)
+              << "Multiplanar external texture transform was not run.";
+          return false;
+        }
+
         auto* storage = tex->As<sem::StorageTexture>();
         auto* ms = tex->As<sem::MultisampledTexture>();
         auto* depth_ms = tex->As<sem::DepthMultisampledTexture>();
diff --git a/src/tint/writer/msl/generator_impl.cc b/src/tint/writer/msl/generator_impl.cc
index 3a8c1dc..f29675e 100644
--- a/src/tint/writer/msl/generator_impl.cc
+++ b/src/tint/writer/msl/generator_impl.cc
@@ -61,7 +61,6 @@
 #include "src/tint/transform/array_length_from_uniform.h"
 #include "src/tint/transform/builtin_polyfill.h"
 #include "src/tint/transform/canonicalize_entry_point_io.h"
-#include "src/tint/transform/external_texture_transform.h"
 #include "src/tint/transform/manager.h"
 #include "src/tint/transform/module_scope_var_to_entry_point_param.h"
 #include "src/tint/transform/pad_array_elements.h"
@@ -174,7 +173,6 @@
     manager.Add<transform::ZeroInitWorkgroupMemory>();
   }
   manager.Add<transform::CanonicalizeEntryPointIO>();
-  manager.Add<transform::ExternalTextureTransform>();
   manager.Add<transform::PromoteInitializersToConstVar>();
 
   manager.Add<transform::VectorizeScalarMatrixConstructors>();
@@ -2366,6 +2364,12 @@
         return true;
       },
       [&](const sem::Texture* tex) {
+        if (tex->Is<sem::ExternalTexture>()) {
+          TINT_ICE(Writer, diagnostics_)
+              << "Multiplanar external texture transform was not run.";
+          return false;
+        }
+
         if (tex->IsAnyOf<sem::DepthTexture, sem::DepthMultisampledTexture>()) {
           out << "depth";
         } else {
diff --git a/src/tint/writer/spirv/builder.cc b/src/tint/writer/spirv/builder.cc
index f3eff71..83f2666 100644
--- a/src/tint/writer/spirv/builder.cc
+++ b/src/tint/writer/spirv/builder.cc
@@ -45,7 +45,6 @@
 #include "src/tint/transform/add_spirv_block_attribute.h"
 #include "src/tint/transform/builtin_polyfill.h"
 #include "src/tint/transform/canonicalize_entry_point_io.h"
-#include "src/tint/transform/external_texture_transform.h"
 #include "src/tint/transform/fold_constants.h"
 #include "src/tint/transform/for_loop_to_loop.h"
 #include "src/tint/transform/manager.h"
@@ -279,7 +278,6 @@
   manager.Add<transform::RemoveUnreachableStatements>();
   manager.Add<transform::SimplifyPointers>();  // Required for arrayLength()
   manager.Add<transform::FoldConstants>();
-  manager.Add<transform::ExternalTextureTransform>();
   manager.Add<transform::VectorizeScalarMatrixConstructors>();
   manager.Add<transform::ForLoopToLoop>();  // Must come after
                                             // ZeroInitWorkgroupMemory
@@ -4033,6 +4031,12 @@
 
 bool Builder::GenerateTextureType(const sem::Texture* texture,
                                   const Operand& result) {
+  if (texture->Is<sem::ExternalTexture>()) {
+    TINT_ICE(Writer, builder_.Diagnostics())
+        << "Multiplanar external texture transform was not run.";
+    return false;
+  }
+
   uint32_t array_literal = 0u;
   const auto dim = texture->dim();
   if (dim == ast::TextureDimension::k2dArray ||