[libc-commits] [libc] [libc] Build with -Wdeprecated, fix some warnings (PR #125373)

[Roland McGrath via libc-commits]

https://github.com/frobtech updated https://github.com/llvm/llvm-project/pull/125373

>From e299436c490f00b2c252290f9b5ea08c83e3997d Mon Sep 17 00:00:00 2001
From: Roland McGrath <mcgrathr at google.com>
Date: Sat, 1 Feb 2025 17:30:36 -0800
Subject: [PATCH 1/2] [libc] Build with -Wdeprecated, fix some warnings

While GCC's -Wdeprecated is on by default and doesn't do much,
Clang's -Wdeprecated enables many more things.  More apply in
C++20, so switch a test file that tickled one to using that.  In
future, C++20 should probably be made the baseline for compiling
all the libc code.
---
 libc/cmake/modules/LLVMLibCCompileOptionRules.cmake | 3 ++-
 libc/src/__support/CPP/span.h                       | 2 ++
 libc/test/src/setjmp/CMakeLists.txt                 | 2 ++
 libc/test/src/setjmp/setjmp_test.cpp                | 2 +-
 4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 12420db331961b..0facb0b9be0c13 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -179,8 +179,9 @@ function(_get_common_compile_options output_var flags)
     endif()
     list(APPEND compile_options "-Wconversion")
     list(APPEND compile_options "-Wno-sign-conversion")
-    # Silence this warning because _Complex is a part of C99.
+    list(APPEND compile_options "-Wdeprecated")
     if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+      # Silence this warning because _Complex is a part of C99.
       list(APPEND compile_options "-fext-numeric-literals")
     else()
       list(APPEND compile_options "-Wno-c99-extensions")
diff --git a/libc/src/__support/CPP/span.h b/libc/src/__support/CPP/span.h
index e9e3dbf169ce02..e5073bd3c9d871 100644
--- a/libc/src/__support/CPP/span.h
+++ b/libc/src/__support/CPP/span.h
@@ -52,6 +52,8 @@ template <typename T> class span {
 
   LIBC_INLINE constexpr span() : span_data(nullptr), span_size(0) {}
 
+  LIBC_INLINE constexpr span(const span&) = default;
+
   LIBC_INLINE constexpr span(pointer first, size_type count)
       : span_data(first), span_size(count) {}
 
diff --git a/libc/test/src/setjmp/CMakeLists.txt b/libc/test/src/setjmp/CMakeLists.txt
index 049df89ba39a6f..392230784bd993 100644
--- a/libc/test/src/setjmp/CMakeLists.txt
+++ b/libc/test/src/setjmp/CMakeLists.txt
@@ -11,6 +11,8 @@ add_libc_unittest(
     libc_setjmp_unittests
   SRCS
     setjmp_test.cpp
+  CXX_STANDARD
+    20
   DEPENDS
     libc.src.setjmp.longjmp
     libc.src.setjmp.setjmp
diff --git a/libc/test/src/setjmp/setjmp_test.cpp b/libc/test/src/setjmp/setjmp_test.cpp
index 9e5f74a1734b35..27113cd6e06311 100644
--- a/libc/test/src/setjmp/setjmp_test.cpp
+++ b/libc/test/src/setjmp/setjmp_test.cpp
@@ -27,7 +27,7 @@ TEST(LlvmLibcSetJmpTest, SetAndJumpBack) {
   // The first time setjmp is called, it should return 0.
   // Subsequent calls will return the value passed to jump_back below.
   if (LIBC_NAMESPACE::setjmp(buf) <= MAX_LOOP) {
-    ++n;
+    n = n + 1;
     jump_back(buf, n);
   }
   ASSERT_EQ(longjmp_called, n);

>From 7ef574fee9bf984748528ac36431fc65c79ffbf3 Mon Sep 17 00:00:00 2001
From: Roland McGrath <mcgrathr at google.com>
Date: Sat, 1 Feb 2025 17:47:28 -0800
Subject: [PATCH 2/2] clang-format

---
 libc/src/__support/CPP/span.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libc/src/__support/CPP/span.h b/libc/src/__support/CPP/span.h
index e5073bd3c9d871..a41c9b744e3702 100644
--- a/libc/src/__support/CPP/span.h
+++ b/libc/src/__support/CPP/span.h
@@ -10,7 +10,7 @@
 
 #include <stddef.h> // For size_t
 
-#include "array.h"       // For array
+#include "array.h" // For array
 #include "src/__support/macros/config.h"
 #include "type_traits.h" // For remove_cv_t, enable_if_t, is_same_v, is_const_v
 
@@ -52,7 +52,7 @@ template <typename T> class span {
 
   LIBC_INLINE constexpr span() : span_data(nullptr), span_size(0) {}
 
-  LIBC_INLINE constexpr span(const span&) = default;
+  LIBC_INLINE constexpr span(const span &) = default;
 
   LIBC_INLINE constexpr span(pointer first, size_type count)
       : span_data(first), span_size(count) {}