[clang][auto-init] Remove -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang

[kees]

Summary

This was deprecated in Clang 16 and scheduled for removal in Clang 18.
Time to remove it.

[MaskRay]

Thanks!

clang/docs/ReleaseNotes.rst

 -----------------------
 
 * ``-Woverriding-t-option`` is renamed to ``-Woverriding-option``.
 * ``-Winterrupt-service-routine`` is renamed to ``-Wexcessive-regsave`` as a generalization
 
 Removed Compiler Flags
 -------------------------
 
+* ``-enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang`` has been removed.
+  It has not been needed to enable ``-ftrivial-auto-var-init=zero`` since Clang 16.
+
 Attribute Changes in Clang
 --------------------------
 - On X86, a warning is now emitted if a function with ``__attribute__((no_caller_saved_registers))``
   calls a function without ``__attribute__((no_caller_saved_registers))``, and is not compiled with
   ``-mgeneral-regs-only``
 - On X86, a function with ``__attribute__((interrupt))`` can now call a function without
   ``__attribute__((no_caller_saved_registers))`` provided that it is compiled with ``-mgeneral-regs-only``
 

clang/include/clang/Driver/Options.td

 // Retired with clang-5.0
 def : Flag<["-"], "fslp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
 def : Flag<["-"], "fno-slp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
 
 // Retired with clang-10.0. Previously controlled X86 MPX ISA.
 def mmpx : Flag<["-"], "mmpx">, Group<clang_ignored_legacy_options_Group>;
 def mno_mpx : Flag<["-"], "mno-mpx">, Group<clang_ignored_legacy_options_Group>;
 
-// Retired with clang-16.0, to provide a deprecation period; it should
-// be removed in Clang 18 or later.
-def enable_trivial_var_init_zero : Flag<["-"], "enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang">,
-  Flags<[NoArgumentUnused]>, Visibility<[ClangOption, CC1Option, CLOption]>,
-  Group<clang_ignored_legacy_options_Group>;
-
 // Group that ignores all gcc optimizations that won't be implemented
 def clang_ignored_gcc_optimization_f_Group : OptionGroup<
   "<clang_ignored_gcc_optimization_f_Group>">, Group<f_Group>, Flags<[Ignored]>;
 
 class DiagnosticOpts<string base>
   : KeyPathAndMacro<"DiagnosticOpts->", base, "DIAG_"> {}
 class LangOpts<string base>
   : KeyPathAndMacro<"LangOpts->", base, "LANG_"> {}

clang/test/Driver/clang_f_opts.c

 // RUN: "%t.r/with spaces/clang" -### -S -target x86_64-unknown-linux -frecord-gcc-switches %s 2>&1 | FileCheck -check-prefix=CHECK-RECORD-GCC-SWITCHES-ESCAPED %s
 // CHECK-RECORD-GCC-SWITCHES-ESCAPED: "-record-command-line" "{{.+}}with\\ spaces{{.+}}"
 // Clean up copy of large binary copied into temp directory to avoid bloat.
 // RUN: rm -f "%t.r/with spaces/clang" || true
 
 // RUN: %clang -### -S -ftrivial-auto-var-init=uninitialized %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-UNINIT %s
 // RUN: %clang -### -S -ftrivial-auto-var-init=pattern %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-PATTERN %s
 // RUN: %clang -### -S -ftrivial-auto-var-init=zero %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-ZERO %s
-// RUN: %clang -### -S -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang \
-// RUN:   -ftrivial-auto-var-init=zero %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-ZERO-ENABLE-DEPRECATED %s
 // CHECK-TRIVIAL-UNINIT-NOT: hasn't been enabled
 // CHECK-TRIVIAL-PATTERN-NOT: hasn't been enabled
 // CHECK-TRIVIAL-ZERO-NOT: hasn't been enabled
-// CHECK-TRIVIAL-ZERO-ENABLE-DEPRECATED: has been deprecated
 
 // RUN: %clang -### -S -ftrivial-auto-var-init=pattern -ftrivial-auto-var-init-stop-after=1 %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-PATTERN-STOP-AFTER %s
 // RUN: %clang -### -S -ftrivial-auto-var-init=zero -ftrivial-auto-var-init-stop-after=1 %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-ZERO-STOP-AFTER %s
 // RUN: not %clang -### -S -ftrivial-auto-var-init-stop-after=0 %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-STOP-AFTER-MISSING-DEPENDENCY %s
 // RUN: not %clang -### -S -ftrivial-auto-var-init=pattern -ftrivial-auto-var-init-stop-after=0 %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-PATTERN-STOP-AFTER-INVALID-VALUE %s
 // RUN: not %clang -### -S -ftrivial-auto-var-init=zero -ftrivial-auto-var-init-stop-after=0 %s 2>&1 | FileCheck -check-prefix=CHECK-TRIVIAL-ZERO-STOP-AFTER-INVALID-VALUE %s
 // CHECK-TRIVIAL-PATTERN-STOP-AFTER-NOT: is used without '-ftrivial-auto-var-init'
 // CHECK-TRIVIAL-PATTERN-STOP-AFTER-NOT: only accepts positive integers