[clang] [clang][SME] Rework streaming mode always_inline errors/warnings (PR #174608)

[Benjamin Maxwell via cfe-commits]

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@@ -1327,12 +1327,15 @@ def PerfConstraintImpliesNoexcept : DiagGroup<"perf-constraint-implies-noexcept"
 // Uniqueness Analysis warnings
 def Consumed       : DiagGroup<"consumed">;
 
+// A warning group related to AArch64 SME function attribues.
+def AArch64SMEAttributes : DiagGroup<"aarch64-sme-attributes">;
+
 // Note that putting warnings in -Wall will not disable them by default. If a
 // warning should be active _only_ when -Wall is passed in, mark it as
 // DefaultIgnore in addition to putting it here.
 def All : DiagGroup<"all", [Most, Parentheses, Switch, SwitchBool,
                             MisleadingIndentation, PackedNonPod,
-                            VLACxxExtension]>;
+                            VLACxxExtension, AArch64SMEAttributes]>;
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MacDue wrote:

The `aarch64-sme-attributes` warnings are all enabled by default (without any extra flags required). This change would be moving one of the warnings to require the `-Wall` flag. 

https://github.com/llvm/llvm-project/pull/174608