Rollup merge of #82270 - asquared31415:asm-syntax-directive-errors, r=nagisa

Emit error when trying to use assembler syntax directives in `asm!`

The `.intel_syntax` and `.att_syntax` assembler directives should not be used, in favor of not specifying a syntax for intel, and in favor of the explicit `att_syntax` option using the inline assembly options.

Closes #79869

compiler/rustc_session/src/session.rs

@@ -793,6 +793,13 @@ impl Session {
         }
     }
 
+    pub fn inline_asm_dialect(&self) -> rustc_ast::LlvmAsmDialect {
+        match self.asm_arch {
+            Some(InlineAsmArch::X86 | InlineAsmArch::X86_64) => rustc_ast::LlvmAsmDialect::Intel,
+            _ => rustc_ast::LlvmAsmDialect::Att,
+        }
+    }
+
     pub fn relocation_model(&self) -> RelocModel {
         self.opts.cg.relocation_model.unwrap_or(self.target.relocation_model)
     }