[libc] Add -Werror for libc tests (llvm#160413)

vinay-deshmukh · web-flow · commit 5d6c00cd0f8f · 2025-10-22T14:32:21.000-04:00
Relates to llvm#119281 Note: 1) As this PR enables `-Werror` for `libc` tests, it's very likely some downstream CI's may fail / start failing, so it's very likely this PR may need to be reverted and re-applied. P.S. I do not have merge permissions, so I will need one of the reviews to merge it for me. Thank you!
diff --git a/libc/cmake/modules/LLVMLibCTestRules.cmake b/libc/cmake/modules/LLVMLibCTestRules.cmake
@@ -38,7 +38,7 @@ function(_get_common_test_compile_options output_var c_test flags)
     list(APPEND compile_options "-Wextra")
     # -DLIBC_WNO_ERROR=ON if you can't build cleanly with -Werror.
     if(NOT LIBC_WNO_ERROR)
-      # list(APPEND compile_options "-Werror")
+      list(APPEND compile_options "-Werror")
     endif()
     list(APPEND compile_options "-Wconversion")
     # FIXME: convert to -Wsign-conversion
diff --git a/libc/test/include/complex_test.cpp b/libc/test/include/complex_test.cpp
@@ -27,8 +27,8 @@ TEST(LlvmLibcComplexTest, CMPLXMacro) {
   EXPECT_CFP_EQ(CMPLXL(1.0l, 0), 1.0l);
 
 #ifdef LIBC_TYPES_HAS_CFLOAT16
-  EXPECT_CFP_EQ(CMPLXF16(0, 1.0), I);
-  EXPECT_CFP_EQ(CMPLXF16(1.0, 0), 1.0);
+  EXPECT_CFP_EQ(CMPLXF16(0, 1.0), static_cast<_Complex _Float16>(I));
+  EXPECT_CFP_EQ(CMPLXF16(1.0, 0), static_cast<_Complex _Float16>(1.0));
 #endif // LIBC_TYPES_HAS_CFLOAT16
 
 #ifdef LIBC_TYPES_HAS_CFLOAT128
diff --git a/libc/test/integration/src/pthread/pthread_barrier_test.cpp b/libc/test/integration/src/pthread/pthread_barrier_test.cpp
@@ -26,7 +26,7 @@
 pthread_barrier_t barrier;
 LIBC_NAMESPACE::cpp::Atomic<int> counter;
 
-void *increment_counter_and_wait(void *args) {
+void *increment_counter_and_wait([[maybe_unused]] void *args) {
   counter.fetch_add(1);
   return reinterpret_cast<void *>(
       LIBC_NAMESPACE::pthread_barrier_wait(&barrier));
@@ -102,7 +102,7 @@ void reused_barrier_test() {
   LIBC_NAMESPACE::pthread_barrier_destroy(&barrier);
 }
 
-void *barrier_wait(void *in) {
+void *barrier_wait([[maybe_unused]] void *in) {
   return reinterpret_cast<void *>(
       LIBC_NAMESPACE::pthread_barrier_wait(&barrier));
 }
diff --git a/libc/test/src/math/exhaustive/bfloat16_add_test.cpp b/libc/test/src/math/exhaustive/bfloat16_add_test.cpp
@@ -23,8 +23,9 @@ struct Bfloat16AddChecker : public virtual LIBC_NAMESPACE::testing::Test {
   using FPBits = LIBC_NAMESPACE::fputil::FPBits<bfloat16>;
   using StorageType = typename FPBits::StorageType;
 
-  uint64_t check(uint16_t x_start, uint16_t x_stop, uint16_t y_start,
-                 uint16_t y_stop, mpfr::RoundingMode rounding) {
+  uint64_t check(uint16_t x_start, uint16_t x_stop,
+                 [[maybe_unused]] uint16_t y_start, uint16_t y_stop,
+                 mpfr::RoundingMode rounding) {
     mpfr::ForceRoundingMode r(rounding);
     if (!r.success)
       return true;
diff --git a/libc/test/src/math/exhaustive/bfloat16_div_test.cpp b/libc/test/src/math/exhaustive/bfloat16_div_test.cpp
@@ -23,8 +23,9 @@ struct Bfloat16DivChecker : public virtual LIBC_NAMESPACE::testing::Test {
   using FPBits = LIBC_NAMESPACE::fputil::FPBits<bfloat16>;
   using StorageType = typename FPBits::StorageType;
 
-  uint64_t check(uint16_t x_start, uint16_t x_stop, uint16_t y_start,
-                 uint16_t y_stop, mpfr::RoundingMode rounding) {
+  uint64_t check(uint16_t x_start, uint16_t x_stop,
+                 [[maybe_unused]] uint16_t y_start, uint16_t y_stop,
+                 mpfr::RoundingMode rounding) {
     mpfr::ForceRoundingMode r(rounding);
     if (!r.success)
       return true;
diff --git a/libc/test/src/math/exhaustive/bfloat16_mul_test.cpp b/libc/test/src/math/exhaustive/bfloat16_mul_test.cpp
@@ -23,8 +23,9 @@ struct Bfloat16MulChecker : public virtual LIBC_NAMESPACE::testing::Test {
   using FPBits = LIBC_NAMESPACE::fputil::FPBits<bfloat16>;
   using StorageType = typename FPBits::StorageType;
 
-  uint64_t check(uint16_t x_start, uint16_t x_stop, uint16_t y_start,
-                 uint16_t y_stop, mpfr::RoundingMode rounding) {
+  uint64_t check(uint16_t x_start, uint16_t x_stop,
+                 [[maybe_unused]] uint16_t y_start, uint16_t y_stop,
+                 mpfr::RoundingMode rounding) {
     mpfr::ForceRoundingMode r(rounding);
     if (!r.success)
       return true;
diff --git a/libc/test/src/math/exhaustive/bfloat16_sub_test.cpp b/libc/test/src/math/exhaustive/bfloat16_sub_test.cpp
@@ -23,8 +23,9 @@ struct Bfloat16SubChecker : public virtual LIBC_NAMESPACE::testing::Test {
   using FPBits = LIBC_NAMESPACE::fputil::FPBits<bfloat16>;
   using StorageType = typename FPBits::StorageType;
 
-  uint64_t check(uint16_t x_start, uint16_t x_stop, uint16_t y_start,
-                 uint16_t y_stop, mpfr::RoundingMode rounding) {
+  uint64_t check(uint16_t x_start, uint16_t x_stop,
+                 [[maybe_unused]] uint16_t y_start, uint16_t y_stop,
+                 mpfr::RoundingMode rounding) {
     mpfr::ForceRoundingMode r(rounding);
     if (!r.success)
       return true;
diff --git a/libc/test/src/signal/sigaltstack_test.cpp b/libc/test/src/signal/sigaltstack_test.cpp
@@ -33,7 +33,7 @@ static void handler(int) {
   // out or mapped to a register.
   uint8_t var[LOCAL_VAR_SIZE];
   for (int i = 0; i < LOCAL_VAR_SIZE; ++i)
-    var[i] = i;
+    var[i] = static_cast<uint8_t>(i);
   // Verify that array is completely on the alt_stack.
   for (int i = 0; i < LOCAL_VAR_SIZE; ++i) {
     if (!(uintptr_t(var + i) < uintptr_t(alt_stack + ALT_STACK_SIZE) &&
diff --git a/libc/test/src/stdio/fileop_test.cpp b/libc/test/src/stdio/fileop_test.cpp
@@ -101,7 +101,7 @@ TEST_F(LlvmLibcFILETest, SimpleFileOperations) {
 
   // This is not a readable file.
   ASSERT_THAT(LIBC_NAMESPACE::fread(data, 1, 1, file),
-              returns(EQ(0)).with_errno(NE(0)));
+              returns(EQ(static_cast<size_t>(0))).with_errno(NE(0)));
 
   ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
 
@@ -175,7 +175,7 @@ TEST_F(LlvmLibcFILETest, FOpenFWriteSizeGreaterThanOne) {
   // Trying to read more should fetch nothing.
   ASSERT_THAT(
       LIBC_NAMESPACE::fread(read_data, sizeof(MyStruct), WRITE_NMEMB, file),
-      returns(EQ(0)).with_errno(EQ(0)));
+      returns(EQ(static_cast<size_t>(0))).with_errno(EQ(0)));
   EXPECT_NE(LIBC_NAMESPACE::feof(file), 0);
   EXPECT_EQ(LIBC_NAMESPACE::ferror(file), 0);
   ASSERT_EQ(LIBC_NAMESPACE::fclose(file), 0);
diff --git a/libc/test/src/stdio/fopen_test.cpp b/libc/test/src/stdio/fopen_test.cpp
@@ -15,15 +15,14 @@
 #include "test/UnitTest/Test.h"
 
 TEST(LlvmLibcFOpenTest, PrintToFile) {
-  int result;
 
   FILE *file =
       LIBC_NAMESPACE::fopen(APPEND_LIBC_TEST("testdata/test.txt"), "w");
   ASSERT_FALSE(file == nullptr);
 
   static constexpr char STRING[] = "A simple string written to a file\n";
-  result = LIBC_NAMESPACE::fwrite(STRING, 1, sizeof(STRING) - 1, file);
-  EXPECT_GE(result, 0);
+  size_t result = LIBC_NAMESPACE::fwrite(STRING, 1, sizeof(STRING) - 1, file);
+  EXPECT_GE(result, static_cast<size_t>(0));
 
   ASSERT_EQ(0, LIBC_NAMESPACE::fclose(file));
 
diff --git a/libc/test/src/sys/socket/linux/send_recv_test.cpp b/libc/test/src/sys/socket/linux/send_recv_test.cpp
@@ -50,13 +50,15 @@ TEST_F(LlvmLibcSendRecvTest, SendFails) {
   const char TEST_MESSAGE[] = "connection terminated";
   const size_t MESSAGE_LEN = sizeof(TEST_MESSAGE);
 
-  ASSERT_THAT(LIBC_NAMESPACE::send(-1, TEST_MESSAGE, MESSAGE_LEN, 0),
-              Fails(EBADF));
+  ASSERT_THAT(
+      static_cast<int>(LIBC_NAMESPACE::send(-1, TEST_MESSAGE, MESSAGE_LEN, 0)),
+      Fails(EBADF));
 }
 
 TEST_F(LlvmLibcSendRecvTest, RecvFails) {
   char buffer[256];
 
-  ASSERT_THAT(LIBC_NAMESPACE::recv(-1, buffer, sizeof(buffer), 0),
-              Fails(EBADF));
+  ASSERT_THAT(
+      static_cast<int>(LIBC_NAMESPACE::recv(-1, buffer, sizeof(buffer), 0)),
+      Fails(EBADF));
 }
diff --git a/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp b/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp
@@ -45,8 +45,9 @@ TEST_F(LlvmLibcSendMsgRecvMsgTest, SucceedsWithSocketPair) {
   send_message.msg_controllen = 0;
   send_message.msg_flags = 0;
 
-  ASSERT_THAT(LIBC_NAMESPACE::sendmsg(sockpair[0], &send_message, 0),
-              Succeeds(static_cast<ssize_t>(MESSAGE_LEN)));
+  ASSERT_THAT(
+      static_cast<int>(LIBC_NAMESPACE::sendmsg(sockpair[0], &send_message, 0)),
+      Succeeds(static_cast<ssize_t>(MESSAGE_LEN)));
 
   char buffer[256];
 
@@ -63,8 +64,9 @@ TEST_F(LlvmLibcSendMsgRecvMsgTest, SucceedsWithSocketPair) {
   recv_message.msg_controllen = 0;
   recv_message.msg_flags = 0;
 
-  ASSERT_THAT(LIBC_NAMESPACE::recvmsg(sockpair[1], &recv_message, 0),
-              Succeeds(static_cast<ssize_t>(MESSAGE_LEN)));
+  ASSERT_THAT(
+      static_cast<int>(LIBC_NAMESPACE::recvmsg(sockpair[1], &recv_message, 0)),
+      Succeeds(static_cast<ssize_t>(MESSAGE_LEN)));
 
   ASSERT_STREQ(buffer, TEST_MESSAGE);
 
@@ -91,7 +93,8 @@ TEST_F(LlvmLibcSendMsgRecvMsgTest, SendFails) {
   send_message.msg_controllen = 0;
   send_message.msg_flags = 0;
 
-  ASSERT_THAT(LIBC_NAMESPACE::sendmsg(-1, &send_message, 0), Fails(EBADF));
+  ASSERT_THAT(static_cast<int>(LIBC_NAMESPACE::sendmsg(-1, &send_message, 0)),
+              Fails(EBADF));
 }
 
 TEST_F(LlvmLibcSendMsgRecvMsgTest, RecvFails) {
@@ -110,5 +113,6 @@ TEST_F(LlvmLibcSendMsgRecvMsgTest, RecvFails) {
   recv_message.msg_controllen = 0;
   recv_message.msg_flags = 0;
 
-  ASSERT_THAT(LIBC_NAMESPACE::recvmsg(-1, &recv_message, 0), Fails(EBADF));
+  ASSERT_THAT(static_cast<int>(LIBC_NAMESPACE::recvmsg(-1, &recv_message, 0)),
+              Fails(EBADF));
 }
diff --git a/libc/test/src/sys/socket/linux/sendto_recvfrom_test.cpp b/libc/test/src/sys/socket/linux/sendto_recvfrom_test.cpp
@@ -54,13 +54,13 @@ TEST_F(LlvmLibcSendToRecvFromTest, SendToFails) {
 
   ASSERT_THAT(
       LIBC_NAMESPACE::sendto(-1, TEST_MESSAGE, MESSAGE_LEN, 0, nullptr, 0),
-      Fails(EBADF));
+      Fails(static_cast<ssize_t>(EBADF), static_cast<ssize_t>(-1)));
 }
 
 TEST_F(LlvmLibcSendToRecvFromTest, RecvFromFails) {
   char buffer[256];
 
   ASSERT_THAT(
       LIBC_NAMESPACE::recvfrom(-1, buffer, sizeof(buffer), 0, nullptr, 0),
-      Fails(EBADF));
+      Fails(static_cast<ssize_t>(EBADF), static_cast<ssize_t>(-1)));
 }
diff --git a/libc/test/src/time/ctime_r_test.cpp b/libc/test/src/time/ctime_r_test.cpp
@@ -23,7 +23,7 @@ TEST_F(LlvmLibcCtimeR, Nullptr) {
   result = LIBC_NAMESPACE::ctime_r(nullptr, buffer);
   ASSERT_STREQ(nullptr, result);
 
-  time_t t;
+  time_t t = 2147483648; // invalid argument
   result = LIBC_NAMESPACE::ctime_r(&t, nullptr);
   ASSERT_STREQ(nullptr, result);
 }
diff --git a/libc/test/src/time/mktime_test.cpp b/libc/test/src/time/mktime_test.cpp
