Preserve exception types in throw diagnostics

Author: maleadt

src/compiler/transform/throws.jl

@@ -116,10 +116,6 @@ function exception_message(sci::StructuredIRCode, def_index, block::Block,
 
     ex = thrown_exception(sci, def_index, block, exception)
     if ex !== nothing
-        if hasfield(typeof(ex), :msg) && isdefined(ex, :msg)
-            msg = getfield(ex, :msg)
-            msg isa AbstractString && return String(msg)
-        end
         return sprint(showerror, ex)
     end
 

test/codegen/integration.jl

@@ -695,7 +695,7 @@ end
     @testset "Julia throws" begin
         @testset "conditional throw lowers to a runtime assertion" begin
             @test @filecheck begin
-                @check "assert {{.*}}x must be positive"
+                @check "assert {{.*}}ArgumentError: x must be positive"
                 code_tiled(Tuple{Int32}) do x
                     x > Int32(0) || throw(ArgumentError("x must be positive"))
                     return

test/codegen/operations.jl

@@ -781,7 +781,7 @@ spec4d = ct.ArraySpec{4}(16, true)
         end
         @test err isa cuTile.CodegenErrors
         @test only(err.errors).msg ==
-            "Vector-vector multiplication is not supported. Use dot(a, b) for inner products, or reshape explicitly."
+            "ArgumentError: Vector-vector multiplication is not supported. Use dot(a, b) for inner products, or reshape explicitly."
     end
 
     @testset "4D batched matmul (2 batch dims)" begin