[libc][test] Remove dependency on sstream in algorithm_test.cpp

Bots have been failing in full build mode because ´#include <sstream>´ would pull pthread which is not possible when code is compiled with ´-freestanding´.

Differential Revision: https://reviews.llvm.org/D128809

libc/test/src/string/memory_utils/CMakeLists.txt

@@ -4,7 +4,7 @@ add_libc_unittest(
     libc_string_unittests
   SRCS
     address_test.cpp
-    # algorithm_test.cpp
+    algorithm_test.cpp
     backend_test.cpp
     elements_test.cpp
     memory_access_test.cpp
@@ -12,7 +12,6 @@ add_libc_unittest(
   COMPILE_OPTIONS
     ${LIBC_COMPILE_OPTIONS_NATIVE}
     -ffreestanding
-    -pthread
   DEPENDS
     libc.src.string.memory_utils.memory_utils
     libc.src.__support.CPP.array

libc/test/src/string/memory_utils/algorithm_test.cpp

@@ -6,7 +6,9 @@
 #include <src/string/memory_utils/algorithm.h>
 #include <src/string/memory_utils/backends.h>
 
-#include <sstream>
+#include <string>
+#include <type_traits>
+#include <vector>
 
 namespace __llvm_libc {
 
@@ -23,7 +25,26 @@ struct alignas(64) Buffer : cpp::Array<char, 128> {
 
 static Buffer buffer1;
 static Buffer buffer2;
-static std::ostringstream LOG;
+struct Logger {
+  Logger &operator<<(const char *str) {
+    Buffer.append(str);
+    return *this;
+  }
+  Logger &operator<<(char c) {
+    Buffer.push_back(c);
+    return *this;
+  }
+  template <typename Scalar>
+  std::enable_if_t<std::is_integral<Scalar>::value, Logger &>
+  operator<<(Scalar number) {
+    Buffer.append(std::to_string(number));
+    return *this;
+  }
+  const std::string &str() const { return Buffer; }
+
+private:
+  std::string Buffer;
+} LOG;
 
 struct TestBackend {
   static constexpr bool IS_BACKEND_TYPE = true;
@@ -72,7 +93,7 @@ struct TestBackend {
 
 struct LlvmLibcAlgorithm : public testing::Test {
   void SetUp() override {
-    LOG = std::ostringstream();
+    LOG = Logger();
     LOG << '\n';
   }
 
@@ -91,11 +112,20 @@ struct LlvmLibcAlgorithm : public testing::Test {
     return trace_.c_str();
   }
 
-  const char *stripComments(const char *expected) {
+  const char *stripComments(std::string expected) {
     expected_.clear();
-    std::stringstream ss(expected);
-    std::string line;
-    while (std::getline(ss, line, '\n')) {
+    // split expected by lines
+    std::vector<std::string> lines;
+    lines.emplace_back();
+    for (const char c : expected) {
+      if (c == '\n') {
+        lines.emplace_back();
+      } else {
+        lines.back().push_back(c);
+      }
+    }
+    // strip comment for each lines
+    for (const std::string &line : lines) {
       const auto pos = line.find('#');
       if (pos == std::string::npos) {
         expected_ += line;
@@ -105,7 +135,8 @@ struct LlvmLibcAlgorithm : public testing::Test {
           log.pop_back();
         expected_ += log;
       }
-      expected_ += '\n';
+      if (expected_.back() != '\n')
+        expected_.push_back('\n');
     }
     return expected_.c_str();
   }