-*- Mode: diff -*-
diff --git a/core/fpdfapi/font/cpdf_cidfont.cpp b/core/fpdfapi/font/cpdf_cidfont.cpp
index 7d2d549b8..c4864060a 100644
--- a/core/fpdfapi/font/cpdf_cidfont.cpp
+++ b/core/fpdfapi/font/cpdf_cidfont.cpp
@@ -754,7 +754,7 @@ int CPDF_CIDFont::GlyphFromCharCode(uint32_t charcode, bool* pVertGlyph) {
         uint32_t maccode = CharCodeFromUnicodeForFreetypeEncoding(
             FT_ENCODING_APPLE_ROMAN, name_unicode);
         index = maccode ? FT_Get_Char_Index(face, maccode)
-                        : FT_Get_Name_Index(face, name);
+                        : FT_Get_Name_Index(face, const_cast<char*>(name));
       }
       if (index == 0 || index == 0xffff)
         return charcode ? static_cast<int>(charcode) : -1;
diff --git a/core/fpdfapi/font/cpdf_truetypefont.cpp b/core/fpdfapi/font/cpdf_truetypefont.cpp
index f19ace9d0..562b015f0 100644
--- a/core/fpdfapi/font/cpdf_truetypefont.cpp
+++ b/core/fpdfapi/font/cpdf_truetypefont.cpp
@@ -90,7 +90,7 @@ void CPDF_TrueTypeFont::LoadGlyphMap() {
               FT_ENCODING_APPLE_ROMAN,
               m_Encoding.UnicodeFromCharCode(charcode));
           if (!maccode) {
-            m_GlyphIndex[charcode] = FT_Get_Name_Index(face, name);
+            m_GlyphIndex[charcode] = FT_Get_Name_Index(face, const_cast<char*>(name));
           } else {
             m_GlyphIndex[charcode] = FT_Get_Char_Index(face, maccode);
           }
@@ -104,7 +104,7 @@ void CPDF_TrueTypeFont::LoadGlyphMap() {
         m_GlyphIndex[charcode] = FT_Get_Char_Index(face, 32);
         continue;
       }
-      m_GlyphIndex[charcode] = FT_Get_Name_Index(face, name);
+      m_GlyphIndex[charcode] = FT_Get_Name_Index(face, const_cast<char*>(name));
       if (m_GlyphIndex[charcode] != 0 || !bToUnicode)
         continue;
 
diff --git a/core/fpdfapi/font/cpdf_type1font.cpp b/core/fpdfapi/font/cpdf_type1font.cpp
index 55510e7d7..2f13f00b8 100644
--- a/core/fpdfapi/font/cpdf_type1font.cpp
+++ b/core/fpdfapi/font/cpdf_type1font.cpp
@@ -263,7 +263,7 @@ void CPDF_Type1Font::LoadGlyphMap() {
                                           static_cast<uint32_t>(charcode));
       if (name) {
         m_Encoding.SetUnicode(charcode, UnicodeFromAdobeName(name));
-        m_GlyphIndex[charcode] = FT_Get_Name_Index(m_Font.GetFaceRec(), name);
+        m_GlyphIndex[charcode] = FT_Get_Name_Index(m_Font.GetFaceRec(), const_cast<char*>(name));
       } else {
         m_GlyphIndex[charcode] = FT_Get_Char_Index(
             m_Font.GetFaceRec(), static_cast<uint32_t>(charcode));
@@ -294,7 +294,7 @@ void CPDF_Type1Font::LoadGlyphMap() {
       continue;
 
     m_Encoding.SetUnicode(charcode, UnicodeFromAdobeName(name));
-    m_GlyphIndex[charcode] = FT_Get_Name_Index(m_Font.GetFaceRec(), name);
+    m_GlyphIndex[charcode] = FT_Get_Name_Index(m_Font.GetFaceRec(), const_cast<char*>(name));
     if (m_GlyphIndex[charcode] != 0)
       continue;
 
diff --git a/core/fpdfdoc/cpdf_metadata.cpp b/core/fpdfdoc/cpdf_metadata.cpp
index 31564f45f..5858549ef 100644
--- a/core/fpdfdoc/cpdf_metadata.cpp
+++ b/core/fpdfdoc/cpdf_metadata.cpp
@@ -87,7 +87,7 @@ std::vector<UnsupportedFeature> CPDF_Metadata::CheckForSharedForm() const {
   CFX_XMLParser parser(stream);
   std::unique_ptr<CFX_XMLDocument> doc = parser.Parse();
   if (!doc)
-    return {};
+    return std::vector<UnsupportedFeature>();
 
   std::vector<UnsupportedFeature> unsupported;
   CheckForSharedFormInternal(/*depth=*/0, doc->GetRoot(), &unsupported);
diff --git a/core/fxcodec/jpx/cjpx_decoder.cpp b/core/fxcodec/jpx/cjpx_decoder.cpp
index 2e7a72aa1..65fb3deaa 100644
--- a/core/fxcodec/jpx/cjpx_decoder.cpp
+++ b/core/fxcodec/jpx/cjpx_decoder.cpp
@@ -74,7 +74,7 @@ absl::optional<OpjImageRgbData> alloc_rgb(size_t size) {
   if (!data.b)
     return absl::nullopt;
 
-  return data;
+  return std::move(data);
 }
 
 void sycc_to_rgb(int offset,
diff --git a/third_party/base/containers/span.h b/third_party/base/containers/span.h
index 435fafa85..d8e8bfbc4 100644
--- a/third_party/base/containers/span.h
+++ b/third_party/base/containers/span.h
@@ -211,7 +211,7 @@ class TRIVIAL_ABI GSL_POINTER span {
 #else
   template <typename Container,
             typename = internal::EnableIfSpanCompatibleContainer<Container, T>>
-  constexpr span(Container& container)
+  span(Container& container)
       : span(container.data(), container.size()) {}
 #endif
 
@@ -225,7 +225,7 @@ class TRIVIAL_ABI GSL_POINTER span {
   // Conversions from spans of compatible types: this allows a span<T> to be
   // seamlessly used as a span<const T>, but not the other way around.
   template <typename U, typename = internal::EnableIfLegalSpanConversion<U, T>>
-  constexpr span(const span<U>& other) : span(other.data(), other.size()) {}
+  span(const span<U>& other) : span(other.data(), other.size()) {}
   span& operator=(const span& other) noexcept {
     if (this != &other) {
       data_ = other.data_;
diff --git a/third_party/base/numerics/safe_conversions_impl.h b/third_party/base/numerics/safe_conversions_impl.h
index 44c921a14..0152a89b7 100644
--- a/third_party/base/numerics/safe_conversions_impl.h
+++ b/third_party/base/numerics/safe_conversions_impl.h
@@ -89,7 +89,7 @@ constexpr typename std::make_unsigned<T>::type SafeUnsignedAbs(T value) {
 
 // TODO(jschuh): Switch to std::is_constant_evaluated() once C++20 is supported.
 // Alternately, the usage could be restructured for "consteval if" in C++23.
-#define IsConstantEvaluated() (__builtin_is_constant_evaluated())
+#define IsConstantEvaluated() (false)
 
 // TODO(jschuh): Debug builds don't reliably propagate constants, so we restrict
 // some accelerated runtime paths to release builds until this can be forced
diff --git a/third_party/libopenjpeg/openjpeg.c b/third_party/libopenjpeg/openjpeg.c
index 9dd4256d7..949d65830 100644
--- a/third_party/libopenjpeg/openjpeg.c
+++ b/third_party/libopenjpeg/openjpeg.c
@@ -358,7 +358,7 @@ OPJ_BOOL OPJ_CALLCONV opj_setup_decoder(opj_codec_t *p_codec,
     return OPJ_FALSE;
 }
 
-OPJ_API OPJ_BOOL OPJ_CALLCONV opj_decoder_set_strict_mode(opj_codec_t *p_codec,
+OPJ_BOOL OPJ_CALLCONV opj_decoder_set_strict_mode(opj_codec_t *p_codec,
         OPJ_BOOL strict)
 {
     if (p_codec) {