[NFC] Do not read past the end of a string_view (#5317)

wasm-s-parser.cpp was detecting the end of type strings by looking for null
characters, but those null characters would be past the end of the relevant
string_view. Bring that code in line with similar code by checking the length of
the string_view instead. Fixes an assertion failure in MSVC debug mode.

Fixes #5312.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index ab6230442..7bdbc69c6 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -1151,18 +1151,18 @@ Type SExpressionWasmBuilder::stringToType(std::string_view str,
                                           bool prefix) {
   if (str.size() >= 3) {
     if (str[0] == 'i') {
-      if (str[1] == '3' && str[2] == '2' && (prefix || str[3] == 0)) {
+      if (str[1] == '3' && str[2] == '2' && (prefix || str.size() == 3)) {
         return Type::i32;
       }
-      if (str[1] == '6' && str[2] == '4' && (prefix || str[3] == 0)) {
+      if (str[1] == '6' && str[2] == '4' && (prefix || str.size() == 3)) {
         return Type::i64;
       }
     }
     if (str[0] == 'f') {
-      if (str[1] == '3' && str[2] == '2' && (prefix || str[3] == 0)) {
+      if (str[1] == '3' && str[2] == '2' && (prefix || str.size() == 3)) {
         return Type::f32;
       }
-      if (str[1] == '6' && str[2] == '4' && (prefix || str[3] == 0)) {
+      if (str[1] == '6' && str[2] == '4' && (prefix || str.size() == 3)) {
         return Type::f64;
       }
     }
@@ -1170,7 +1170,7 @@ Type SExpressionWasmBuilder::stringToType(std::string_view str,
   if (str.size() >= 4) {
     if (str[0] == 'v') {
       if (str[1] == '1' && str[2] == '2' && str[3] == '8' &&
-          (prefix || str[4] == 0)) {
+          (prefix || str.size() == 4)) {
         return Type::v128;
       }
     }