StringSwitch cannot be copied (take 2).

This prevents StringSwitch from being used with 'auto', which is
important because the inferred type is StringSwitch rather than the
result type. This is a problem because StringSwitch stores addresses
of temporary values rather than copying or moving the value into its
own storage.

This is a compromise that still allows wrapping StringSwitch in other
temporary structures, which (unlike StringSwitch) may be non-trivial
to set up and therefore want to at least be movable. (For an example,
see QueryParser.cpp in clang-tools-extra.)

Changing this uncovered the bug in PassBuilder, also in this patch.
Clang doesn't seem to have any occurrences of the issue.

Re-commit of r276652.

llvm-svn: 276671

1 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 6c0ceb0..594fe81 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -334,13 +334,13 @@ bool PassBuilder::parseModulePassName(ModulePassManager &MPM, StringRef Name,
       return false;
     assert(Matches.size() == 3 && "Must capture two matched strings!");
 
-    auto L = StringSwitch<OptimizationLevel>(Matches[2])
-                 .Case("O0", O0)
-                 .Case("O1", O1)
-                 .Case("O2", O2)
-                 .Case("O3", O3)
-                 .Case("Os", Os)
-                 .Case("Oz", Oz);
+    OptimizationLevel L = StringSwitch<OptimizationLevel>(Matches[2])
+        .Case("O0", O0)
+        .Case("O1", O1)
+        .Case("O2", O2)
+        .Case("O3", O3)
+        .Case("Os", Os)
+        .Case("Oz", Oz);
 
     if (Matches[1] == "default") {
       addPerModuleDefaultPipeline(MPM, L, DebugLogging);