[Demangle] convert itaniumDemangle and nonMicrosoftDemangle to use std::string_view

D149104 converted llvm::demangle to use std::string_view. Enabling
"expensive checks" (via -DLLVM_ENABLE_EXPENSIVE_CHECKS=ON) causes
lld/test/wasm/why-extract.s to fail. The reason for this is obscure:

Reason #10007 why std::string_view is dangerous:
Consider the following pattern:

  std::string_view s = ...;
  const char *c = s.data();
  std::strlen(c);

Is c a NUL-terminated C style string? It depends; but if it's not then
it's not safe to call std::strlen on the std::string_view::data().
std::string_view::length() should be used instead.

Fixing this fixes the one lone test that caught this.

microsoftDemangle, rustDemangle, and dlangDemangle should get this same
treatment, too. I will do that next.

Reviewed By: MaskRay, efriedma

Differential Revision: https://reviews.llvm.org/D149675

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Demangle/ItaniumDemangle.cpp b/llvm/lib/Demangle/ItaniumDemangle.cpp
index b1a8832..f2ce6eb 100644
--- a/llvm/lib/Demangle/ItaniumDemangle.cpp
+++ b/llvm/lib/Demangle/ItaniumDemangle.cpp
@@ -365,11 +365,12 @@ public:
 
 using Demangler = itanium_demangle::ManglingParser<DefaultAllocator>;
 
-char *llvm::itaniumDemangle(const char *MangledName) {
-  if (!MangledName)
+char *llvm::itaniumDemangle(std::string_view MangledName) {
+  if (MangledName.empty())
     return nullptr;
 
-  Demangler Parser(MangledName, MangledName + std::strlen(MangledName));
+  Demangler Parser(MangledName.data(),
+                   MangledName.data() + MangledName.length());
   Node *AST = Parser.parse();
   if (!AST)
     return nullptr;