Switch from crates.io spirv-tools 0.13.0 to the Rust-GPU/SPIRV-Tools
repository via git dependency. This provides access to the new pure-Rust
SPIR-V validator and egglog-based optimizer.
When using as a git dependency, set SPIRV_HEADERS_PATH to point to a
local SPIRV-Headers checkout since the submodule isn't available.

Adapt to changes in rspirv 0.12.0+sdk-1.4.335.0:
- Replace `rspirv::grammar::reflect::is_type(op)` with `op.is_type()`
- Replace `rspirv::grammar::reflect::is_constant(op)` with `op.is_constant()`
- Update `type_float_id` to include FPEncoding parameter (None)
- Change `MemorySemantics::NONE` to `MemorySemantics::RELAXED`
- Change `Decoration::UserTypeGOOGLE` to `Decoration::UserSemantic`
- Update ExecutionMode NV suffixes to EXT/KHR (OutputLinesNV → OutputLinesEXT, etc.)
- Add aliases for DemoteToHelperInvocationEXT and IsHelperInvocationEXT
- Update ImageOperands and MemorySemantics KHR constants (now unified)
- Add stubs for new operand kinds (RawAccessChainOperands, CooperativeMatrixReduce, etc.)
- Update renamed ops (FinalizeNodePayloadsAMDX → EnqueueNodePayloadsAMDX, etc.)
- Add catch-all for new ops in spirv_type_constraints

Improve spirv-val error messages by looking up source locations from
SrcLocDecoration annotations:
- Add validation_err.rs module to parse validation errors and look up
  source spans from the SPIR-V module's custom SrcLocDecoration
- Strip SrcLocDecoration and ZombieDecoration before validation (these
  are invalid on functions) but keep the original module for span lookup
- Add --preserve-debug-decorations flag to optionally keep decorations
- Add SrcLocDecoration to entry point interface variables so validation
  errors for conflicting locations show the relevant source spans
- Keep decorations in linker output (they're stripped after validation)
For location conflict errors, the error message now shows:
- The specific variable causing the conflict with its source location
- The conflicting variable with its source location
- A help message explaining why the conflict occurs (e.g., Mat4 uses 4 locations)

Update Cargo.toml feature documentation:
- The use-compiled-tools and use-installed-tools features are now no-ops
  since we use a pure Rust implementation of spirv-tools
- Keep features for backward compatibility with existing build configurations
- Fix typo: rustc_cogeden_spirv → rustc_codegen_spirv
Update test expectations:
- explicit_overlap.stderr: Now shows rich error with source spans
- mesh_shader.stderr: NV suffixes updated to EXT (OutputPrimitivesNV → OutputPrimitivesEXT, etc.)
- member_ref_arg-broken: Updated line numbers and add normalizer for new error format

Avoids assembling the original module to a binary and then parsing it back.
The validation error context can now use the Module directly for span lookups.

Provides helpful diagnostics when SPIR-V validation fails due to using
a pointer from an invalid source (like OpCompositeExtract) with memory
operations (OpLoad/OpStore) in logical addressing mode.

The error now shows:
- Which instruction cannot use the pointer
- What produced the invalid pointer
- Explanation of logical addressing mode restrictions
- The relevant SPIR-V instructions for context

The error context already makes it clear this is a validation error.

Add rich error handlers with helpful hints for:
- MissingInstructionCapability / MissingOperandCapability
- MissingDescriptorSetDecoration / MissingBindingDecoration
- InvalidBlockLayout
- InvalidBuiltInType

These handlers provide user-friendly rustc diagnostics with source
spans (when available) and actionable hints for fixing common issues.

- Inline format args (uninlined_format_args)
- Collapse nested if statements using let chains (collapsible_if)
- Add backticks around SPIR-V terms in doc comments (doc_markdown)
- Remove unused &self from format_multi_location_hint (unused_self)
- Use map_or instead of map().unwrap_or() (map_unwrap_or)

Picks up 968069d2 which allows VulkanMemoryModel capability on
Vulkan 1.1 via the SPV_KHR_vulkan_memory_model extension, matching
the C++ spirv-val behavior.

Picks up d8c6037a which handles context-dependent number literals
in OpConstant, encoding integer text for float types as the float
value's IEEE 754 bits (matching C++ spirv-as).

The assembler's translate_function_parameter used rspirv Builder's
auto-ID generation which has a separate counter from the module
builder, causing OpFunction and OpFunctionParameter to get the same
result ID. This fixes the names_and_decorations and
use_exported_func_param_attr linker test failures.

Includes Fragment-only execution mode validation, OpLifetimeStart/Stop
validation, group operation validation, and integer dot product validation.

… removal

Updates to SPIRV-Tools commit 90a479a2 which corrects
required_spirv_version_for_extension to match the SPIR-V spec,
removing incorrect version requirements for extensions like
SPV_EXT_descriptor_indexing that only require SPIR-V 1.0.

Updates to SPIRV-Tools commit 38824bc8 which removes
SPV_KHR_ray_tracing and SPV_KHR_ray_tracing_position_fetch from the
extension version check to match C++ behavior, fixing compiletest
failures on vulkan1.1 targets.

- Add ShaderViewportMaskNV, ShaderViewportIndexLayerEXT, and
  SPV_NV_viewport_array2 to all-builtins.rs compile flags to satisfy
  ShaderStereoViewNV capability dependency chain.

- Add rspirv/spirv patch to difftest workspace Cargo.toml to match
  root workspace, fixing compilation errors from newer SPIR-V opcodes
  (ConditionalEntryPointINTEL, TypeUntypedPointerKHR, etc.) that only
  exist in the sdk-update branch.

Updates to SPIRV-Tools commit 83c90d6e which fixes operand extension
validation to use ANY-of semantics, matching the capability fix. This
resolves the SPV_EXT_mesh_shader validation error in all-builtins.rs
where decoration operands listed both NV and EXT mesh shader extensions
as alternatives.

…s test

The Rust SPIR-V validator correctly checks that BuiltIn decoration
operands have their required capabilities declared. The clip_distance
and cull_distance builtins require the ClipDistance and CullDistance
capabilities respectively.