[clang] [Sema] Warn about omitting deprecated enumerator in switch (PR #138562)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Hans Wennborg (zmodem)

<details>
<summary>Changes</summary>

This undoes part of 3e4e3b17c14c15c23c0ed18ca9165b42b1b13ae3 which added the "Omitting a deprecated constant is ok; it should never materialize." logic.

That seems wrong: deprecated means the enumerator is likely to be removed in future versions, not that it cannot materialize.

---
Full diff: https://github.com/llvm/llvm-project/pull/138562.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaStmt.cpp (+5-1) 
- (modified) clang/test/Sema/switch-availability.c (+1-1) 


``````````diff
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index e8c1f8490342a..990d2fadaf5aa 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -1667,8 +1667,12 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
         // Don't warn about omitted unavailable EnumConstantDecls.
         switch (EI->second->getAvailability()) {
         case AR_Deprecated:
-          // Omitting a deprecated constant is ok; it should never materialize.
+          // Deprecated enumerators still need to be handled: they may be
+          // deprecated, but can still occur.
+          break;
+
         case AR_Unavailable:
+          // Omitting an unavailable enumerator is ok; it should never occur.
           continue;
 
         case AR_NotYetIntroduced:
diff --git a/clang/test/Sema/switch-availability.c b/clang/test/Sema/switch-availability.c
index 888edddac463d..b4f8726addc0b 100644
--- a/clang/test/Sema/switch-availability.c
+++ b/clang/test/Sema/switch-availability.c
@@ -15,7 +15,7 @@ enum SwitchTwo {
 };
 
 void testSwitchTwo(enum SwitchTwo st) {
-  switch (st) {} // expected-warning{{enumeration values 'Vim' and 'Emacs' not handled in switch}}
+  switch (st) {} // expected-warning{{enumeration values 'Ed', 'Vim' and 'Emacs' not handled in switch}}
 }
 
 enum SwitchThree {

``````````

</details>


https://github.com/llvm/llvm-project/pull/138562