Make `SanitizerSafeCopy()` constexpr, and check for constant evaluation (#1399)

Also update test Docker container so that LTS patches can be tested

This patch cherry-picks 2 commits:
a0f9b465
35e8e3f7

absl/base/config.h

@@ -112,7 +112,7 @@
 // LTS releases can be obtained from
 // https://github.com/abseil/abseil-cpp/releases.
 #define ABSL_LTS_RELEASE_VERSION 20230125
-#define ABSL_LTS_RELEASE_PATCH_LEVEL 0
+#define ABSL_LTS_RELEASE_PATCH_LEVEL 1
 
 // Helper macro to convert a CPP variable to a string literal.
 #define ABSL_INTERNAL_DO_TOKEN_STR(x) #x

absl/strings/internal/cord_internal.h

@@ -768,7 +768,8 @@ class InlineData {
     }
 
 #ifdef ABSL_INTERNAL_CORD_HAVE_SANITIZER
-    Rep SanitizerSafeCopy() const {
+    constexpr Rep SanitizerSafeCopy() const {
+      if (!absl::is_constant_evaluated()) {
         Rep res;
         if (is_tree()) {
           res = *this;
@@ -777,9 +778,12 @@ class InlineData {
           memcpy(res.as_chars(), as_chars(), inline_size());
         }
         return res;
+      } else {
+        return *this;
+      }
     }
 #else
-    const Rep& SanitizerSafeCopy() const { return *this; }
+    constexpr const Rep& SanitizerSafeCopy() const { return *this; }
 #endif
 
     // If the data has length <= kMaxInline, we store it in `data`, and

ci/linux_docker_containers.sh

@@ -16,6 +16,6 @@
 # Test scripts should source this file to get the identifiers.
 
 readonly LINUX_ALPINE_CONTAINER="gcr.io/google.com/absl-177019/alpine:20201026"
-readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20220217"
-readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20220217"
+readonly LINUX_CLANG_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20230217"
+readonly LINUX_GCC_LATEST_CONTAINER="gcr.io/google.com/absl-177019/linux_hybrid-latest:20230217"
 readonly LINUX_GCC_FLOOR_CONTAINER="gcr.io/google.com/absl-177019/linux_gcc-floor:20230120"