Minor mlib tweaks and fixes

CMakeLists.txt

@@ -164,13 +164,7 @@ configure_file (
 
 # Define the mlib target, which is private and header-only. It is not exported
 # nor are its headers installed.
-add_library (_mongo-mlib INTERFACE)
-add_library (mongo::mlib ALIAS _mongo-mlib)
-set_property(
-   TARGET _mongo-mlib
-   APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS
-   MLIB_USER
-   )
+include (./src/mlib/mlib.cmake)
 
 # kms-message
 add_subdirectory (kms-message)
@@ -405,12 +399,6 @@ add_test (
    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
    )
 
-foreach (test IN ITEMS path str)
-   add_executable (mlib.${test}.test src/mlib/${test}.test.c)
-   add_test (mlib.${test} mlib.${test}.test)
-   target_link_libraries (mlib.${test}.test PRIVATE mongo::mlib)
-endforeach ()
-
 # Exclude example-state-machine since it requires native crypto.
 if (NOT MONGOCRYPT_CRYPTO STREQUAL none)
    # Define example-state-machine
@@ -453,10 +441,6 @@ install (
    INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
 )
 
-# This export set is not installed, and is only to allow export() of the mlib-using targets
-install (TARGETS _mongo-mlib EXPORT _exports_for_export)
-export (EXPORT _exports_for_export)
-
 install (
    FILES
       ${MONGOCRYPT_PUBLIC_HEADERS}

src/mlib/error.h

@@ -19,7 +19,7 @@
  * @return mstr A new string containing the resulting error. Must be freed with
  * @ref mstr_free().
  */
-static inline mstr
+mlib_inline_def mstr
 merror_system_error_string (int errn)
 {
 #ifdef _WIN32

src/mlib/linkcheck-1.test.c

@@ -0,0 +1,7 @@
+#include "./str.h"
+
+void *
+get_func_addr_1 ()
+{
+   return &mstr_new;
+}

src/mlib/linkcheck-2.test.c

@@ -0,0 +1,7 @@
+#include "./str.h"
+
+void *
+get_func_addr_2 ()
+{
+   return &mstr_new;
+}

src/mlib/linkcheck.test.c

@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+extern void *
+get_func_addr_1 ();
+extern void *
+get_func_addr_2 ();
+
+int
+main ()
+{
+   if (get_func_addr_1 () != get_func_addr_2 ()) {
+      fputs ("Multiply-defined symbols were not properly merged.", stderr);
+      return 1;
+   }
+}

src/mlib/macros.h

@@ -0,0 +1,48 @@
+#ifndef MLIB_MACROS_H
+#define MLIB_MACROS_H
+
+#include "./user-check.h"
+
+/**
+ * @macro mlib_inline Expands to the compiler's "inline" keyword. On C99, just
+ * 'inline'. On older compilers pre-C99, an implementation-defined "inline"
+ */
+
+// clang-format off
+#if defined(__GNUC__) || defined(__clang__) || (defined(_MSC_VER) && _MSC_VER >= 1900)
+    #define mlib_inline inline
+#elif defined(_MSC_VER)
+    #define mlib_inline __inline
+#else
+    #define mlib_inline _Do_not_know_how_to_say_inline_on_this_compiler
+#endif
+
+/**
+ * @macro mlib_inline_def
+ * @brief Declare a function to be inline-defined, but with external linkage.
+ *
+ * This has the effect that there will be only one definiton if the final
+ * program, even if the function is defined in multiple translation units
+ * (e.g as the result of #inclusion). This mimicks the linkage behavior of
+ * C++ 'inline' keyword, which is not shared by C99's 'inline'.
+ */
+#ifdef __INTELLISENSE__
+    // Give a pretty definition for intellisense readers
+    #define mlib_inline_def inline
+#elif defined(_WIN32)
+    #ifdef __GNUC__
+        #define mlib_inline_def extern __attribute__((weak, visibility("hidden")))
+    #else
+        // On MSVC/Windows, inline functions are implicitly in COMDAT, even in C
+        #define mlib_inline_def extern mlib_inline
+    #endif
+#else
+    // On other platforms, declare the symbol "weak" to cause symbol merging,
+    // and "hidden" to disable the ability for the symbol to be overridden via
+    // interposition
+    #define mlib_inline_def extern __attribute__((weak, visibility("hidden")))
+#endif
+
+// clang-format on
+
+#endif // MLIB_MACROS_H

src/mlib/mlib.cmake

@@ -0,0 +1,38 @@
+set (MLIB_SRC_DIR "${CMAKE_CURRENT_LIST_DIR}")
+
+add_library (_mongo-mlib INTERFACE)
+get_filename_component (_inc_dir "${MLIB_SRC_DIR}" DIRECTORY)
+target_include_directories (_mongo-mlib INTERFACE "${_inc_dir}")
+target_compile_definitions (_mongo-mlib INTERFACE MLIB_USER)
+add_library (mongo::mlib ALIAS _mongo-mlib)
+
+set (_components error path str thread user-check)
+foreach (comp IN LISTS _components)
+    set (test_file "${MLIB_SRC_DIR}/${comp}.test.c")
+    if (EXISTS "${test_file}")
+        add_executable (mlib.test.${comp} "${test_file}")
+        target_link_libraries (mlib.test.${comp} PRIVATE mongo::mlib)
+        add_test (mlib.test.${comp} mlib.test.${comp})
+        list (APPEND MLIB_SOURCE "${test_file}")
+    endif ()
+endforeach ()
+
+# This is only here to support export() of mongo::mlib-linked targets.
+# Nothing is actually installed
+install (TARGETS _mongo-mlib EXPORT _mongo-mlib)
+export (EXPORT _mongo-mlib)
+
+function (targets_use_mlib)
+    foreach (t IN LISTS ARGV)
+        target_link_libraries("${t}" PRIVATE $<BUILD_INTERFACE:mongo::mlib>)
+    endforeach ()
+endfunction ()
+
+add_executable (mlib.test.comdat-link
+    "${MLIB_SRC_DIR}/linkcheck-1.test.c"
+    "${MLIB_SRC_DIR}/linkcheck-2.test.c"
+    "${MLIB_SRC_DIR}/linkcheck.test.c"
+    )
+
+add_test (mlib.test.comdat-link mlib.test.comdat-link)
+targets_use_mlib (mlib.test.comdat-link)

src/mlib/path.h

@@ -4,6 +4,7 @@
 #include "./user-check.h"
 
 #include "./str.h"
+#include "./macros.h"
 
 #include <inttypes.h>
 
@@ -34,7 +35,7 @@ typedef enum mpath_format {
  * @param c A path character
  * @param f The path format to use
  */
-static inline bool
+mlib_inline_def bool
 mpath_is_sep (char c, mpath_format f)
 {
    if (f == MPATH_WIN32) {
@@ -47,7 +48,7 @@ mpath_is_sep (char c, mpath_format f)
 /**
  * @brief Obtain the preferred path separator character for the given format
  */
-static inline char
+mlib_inline_def char
 mpath_preferred_sep (mpath_format f)
 {
    if (f == MPATH_WIN32) {
@@ -63,7 +64,7 @@ mpath_preferred_sep (mpath_format f)
  *
  * @return mstr A new string which must be freed with mstr_free()
  */
-static inline mstr
+mlib_inline_def mstr
 mpath_current_path ()
 {
 #if _WIN32
@@ -96,7 +97,7 @@ mpath_current_path ()
 /**
  * @brief Determine whether the given path string has a trailing path separator
  */
-static inline bool
+mlib_inline_def bool
 mpath_has_trailing_sep (mstr_view path, mpath_format f)
 {
    return path.len && mpath_is_sep (path.data[path.len - 1], f);
@@ -105,7 +106,7 @@ mpath_has_trailing_sep (mstr_view path, mpath_format f)
 /**
  * @brief Obtain the parent path of the given path.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_parent (mstr_view path, mpath_format f)
 {
    if (mpath_has_trailing_sep (path, f)) {
@@ -133,7 +134,7 @@ mpath_parent (mstr_view path, mpath_format f)
  * The returned path will include no directory separators. If the given path
  * ends with a directory separator, the single-dot '.' path is returned instead.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_filename (mstr_view path, mpath_format f)
 {
    if (!path.len) {
@@ -163,7 +164,7 @@ mpath_filename (mstr_view path, mpath_format f)
  * @param f The path format to use
  * @return mstr A new string resulting from the join
  */
-static inline mstr
+mlib_inline_def mstr
 mpath_join (mstr_view base, mstr_view suffix, mpath_format f)
 {
    if (!base.len) {
@@ -194,7 +195,7 @@ mpath_join (mstr_view base, mstr_view suffix, mpath_format f)
  * For the Windows format, this will return the drive letter, if present.
  * Otherwise, this will return an empty string.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_root_name (mstr_view path, mpath_format f)
 {
    if (f == MPATH_WIN32 && path.len > 1) {
@@ -212,7 +213,7 @@ mpath_root_name (mstr_view path, mpath_format f)
  *
  * @note This will not include the drive letter of a Win32 path.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_root_directory (mstr_view path, mpath_format f)
 {
    mstr_view rname = mpath_root_name (path, f);
@@ -229,7 +230,7 @@ mpath_root_directory (mstr_view path, mpath_format f)
  *
  * This will include both the root name and the root filepath, if present.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_root_path (mstr_view path, mpath_format f)
 {
    mstr_view rname = mpath_root_name (path, f);
@@ -243,7 +244,7 @@ mpath_root_path (mstr_view path, mpath_format f)
  *
  * @note A Win32 filepath without a drive letter is not absolute!
  */
-static inline bool
+mlib_inline_def bool
 mpath_is_absolute (mstr_view path, mpath_format f)
 {
    if (f == MPATH_WIN32) {
@@ -263,7 +264,7 @@ mpath_is_absolute (mstr_view path, mpath_format f)
  * If the path has a root path, returns the content of the path following that
  * root path, otherwise returns the same path itself.
  */
-static inline mstr_view
+mlib_inline_def mstr_view
 mpath_relative_path (mstr_view path, mpath_format f)
 {
    mstr_view root = mpath_root_path (path, f);
@@ -276,7 +277,7 @@ mpath_relative_path (mstr_view path, mpath_format f)
  *
  * @note The return value must be freed with mstr_free()
  */
-static inline mstr
+mlib_inline_def mstr
 mpath_to_format (mpath_format from, mstr_view path, mpath_format to)
 {
    mstr_mut ret = mstr_new (path.len);
@@ -296,7 +297,7 @@ mpath_to_format (mpath_format from, mstr_view path, mpath_format to)
 /**
  * @brief Determine whether the given path is relative (not absolute)
  */
-static inline bool
+mlib_inline_def bool
 mpath_is_relative (mstr_view path, mpath_format f)
 {
    return !mpath_is_absolute (path, f);
@@ -307,7 +308,7 @@ mpath_is_relative (mstr_view path, mpath_format f)
  *
  * @note The return value must be freed with mstr_free()
  */
-static inline mstr
+mlib_inline_def mstr
 mpath_absolute (mstr_view path, mpath_format f);
 
 /**
@@ -320,7 +321,7 @@ mpath_absolute (mstr_view path, mpath_format f);
  * @note If `base` is also a relative path, it will also be given to
  * mpath_absolute() to resolve it.
  */
-static inline mstr
+mlib_inline_def mstr
 mpath_absolute_from (mstr_view path, mstr_view base, mpath_format f)
 {
    mstr_view rname = mpath_root_name (path, f);
@@ -363,7 +364,7 @@ mpath_absolute_from (mstr_view path, mstr_view base, mpath_format f)
    }
 }
 
-static inline mstr
+mlib_inline_def mstr
 mpath_absolute (mstr_view path, mpath_format f)
 {
    if (mpath_is_absolute (path, f)) {