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name: webrtc/prefer-constexpr-absl-string-view-for-string-constants description: When defining compile-time string constants or fixed arrays, use constexpr absl::string_view or constexpr char[] instead of std::string or pointer constants rubric: readability severity: blocking

Rule. Define compile-time string constants and fixed lookup arrays using constexpr absl::string_view (or constexpr std::array<absl::string_view, N>) rather than constexpr std::string, std::array<std::string, N>, or raw const char* pointers. When constants or arrays must bind implicitly to const std::string& parameters in callees that cannot be updated to string views, use character arrays (constexpr char[] or constexpr char[][N]).

Why. Using constexpr absl::string_view ensures compile-time initialization, avoiding startup dynamic initialization and non-portable constexpr std::string compilation issues. Because absl::string_view does not convert implicitly to const std::string&, constexpr char[] arrays provide a compile-time constant fallback for APIs requiring const std::string&.

Examples

Bad:

// String constant with pointer decay or non-constexpr initialization:
const char kAudioMid1[] = "a1";
const char* kCodecName = "VP8";

// std::string triggers dynamic initialization or is not portably constexpr:
const std::array<std::string, 4> kValidIceServiceTypes{"stun", "stuns", "turn",
                                                       "turns"};
constexpr std::array<std::string, 2> kStreams{"stream1", "stream2"};

Good:

// Compile-time string constants:
constexpr absl::string_view kAudioMid1 = "a1";
constexpr absl::string_view kCodecName = "VP8";

// Compile-time string view array avoids runtime dynamic initialization:
constexpr std::array<absl::string_view, 4> kValidIceServiceTypes{
    "stun", "stuns", "turn", "turns"};

// Use constexpr char arrays when parameters require const std::string&:
constexpr char kStreams[][8] = {"stream1", "stream2"};