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Build failure with GCC 14 (initialization from incompatible pointer type) #41

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ebourg opened this issue Dec 11, 2024 · 1 comment
Open

Build failure with GCC 14 (initialization from incompatible pointer type) #41

ebourg opened this issue Dec 11, 2024 · 1 comment
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@aclemons

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@ebourg
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ebourg commented Dec 11, 2024

Hi,

Readline fails to build with GCC 14, we get the following error in Debian:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1075200

gcc -I /usr/lib/jvm/default-java/include -I /usr/lib/jvm/default-java/include/linux -I /usr/lib/jvm/default-java/include -I /usr/lib/jvm/default-java/include/linux -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/libreadline-java-0.8.0.1+dfsg=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -fPIC -DPOSIX -fPIC -DPOSIX -DJavaReadline \
                                   -c org_gnu_readline_Readline.c
org_gnu_readline_Readline.c:85:3: error: initialization of 'int *' from incompatible pointer type 'long unsigned int *' [-Wincompatible-pointer-types]
   85 |   &rl_readline_state,
      |   ^
org_gnu_readline_Readline.c:85:3: note: (near initialization for 'globalIntegerInternals[2]')
org_gnu_readline_Readline.c:120:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  120 |  /* const */ &rl_library_version,
      |              ^
org_gnu_readline_Readline.c:120:14: note: (near initialization for 'globalStringInternals[0]')
org_gnu_readline_Readline.c:121:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  121 |  /* const */ &rl_readline_name,
      |              ^
org_gnu_readline_Readline.c:121:14: note: (near initialization for 'globalStringInternals[1]')
org_gnu_readline_Readline.c:124:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  124 |  /* const */ &rl_terminal_name,
      |              ^
org_gnu_readline_Readline.c:124:14: note: (near initialization for 'globalStringInternals[4]')
org_gnu_readline_Readline.c:126:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  126 |  /* const */ &rl_basic_word_break_characters,
      |              ^
org_gnu_readline_Readline.c:126:14: note: (near initialization for 'globalStringInternals[6]')
org_gnu_readline_Readline.c:127:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  127 |  /* const */ &rl_completer_word_break_characters,
      |              ^
org_gnu_readline_Readline.c:127:14: note: (near initialization for 'globalStringInternals[7]')
org_gnu_readline_Readline.c:128:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  128 |  /* const */ &rl_completer_quote_characters,
      |              ^
org_gnu_readline_Readline.c:128:14: note: (near initialization for 'globalStringInternals[8]')
org_gnu_readline_Readline.c:129:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  129 |  /* const */ &rl_basic_quote_characters,
      |              ^
org_gnu_readline_Readline.c:129:14: note: (near initialization for 'globalStringInternals[9]')
org_gnu_readline_Readline.c:130:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  130 |  /* const */ &rl_filename_quote_characters,
      |              ^
org_gnu_readline_Readline.c:130:14: note: (near initialization for 'globalStringInternals[10]')
org_gnu_readline_Readline.c:131:14: error: initialization of 'char **' from incompatible pointer type 'const char **' [-Wincompatible-pointer-types]
  131 |  /* const */ &rl_special_prefixes,
      |              ^
org_gnu_readline_Readline.c:131:14: note: (near initialization for 'globalStringInternals[11]')
aclemons added a commit that referenced this issue Dec 11, 2024
@aclemons
Setup tests to run all multiple ubuntu versions.
93e1cb1 
We have some compile issues on 24.04. The open issue #41 is tracking
this. We'll enable 24.04 when we commit the fix for that issue.
@aclemons aclemons mentioned this issue Dec 11, 2024
Merged
aclemons added a commit that referenced this issue Dec 12, 2024
@aclemons
Fix declaration of env parameter in fromjstring/tojstring functions.
8078536 
These should take a pointer to a JNIEnv. These were introduced in b178aa0 to
replace:

```c
static char* utf2ucs(const char *utf8, char *ucs, size_t n);
static char* ucs2utf(const char *ucs, char *utf8, size_t n);
```

They were added as:

```c
static char* fromjstring(const JNIEnv *env, jstring value);
static jstring tojstring(const JNIEnv *env, const char* value);
```

In this case however, we actually just wanted to declare these as a
constant pointer not a pointer to a constant.

Newer gcc versions complain with:

```
org_gnu_readline_Readline.c: In function ‘fromjstring’:
org_gnu_readline_Readline.c:780:54: warning: passing argument 1 of ‘((const struct JNINativeInterface_ *)*env)->GetObjectClass’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  780 |   const jclass jstringClass = (*env)->GetObjectClass(env, value);
      |                                                      ^~~
org_gnu_readline_Readline.c:780:54: note: expected ‘const struct JNINativeInterface_ **’ but argument is of type ‘const struct JNINativeInterface_ * const*’
org_gnu_readline_Readline.c:781:58: warning: passing argument 1 of ‘((const struct JNINativeInterface_ *)*env)->GetMethodID’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  781 |   const jmethodID getBytesMethodId = (*env)->GetMethodID(env, jstringClass, "getBytes", "()[B");
      |                                                          ^~~
org_gnu_readline_Readline.c:781:58: note: expected ‘const struct JNINativeInterface_ **’ but argument is of type ‘const struct JNINativeInterface_ * const*’
org_gnu_readline_Readline.c:783:74: warning: passing argument 1 of ‘((const struct JNINativeInterface_ *)*env)->CallObjectMethod’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  783 |   const jbyteArray jstringJBytes = (jbyteArray) (*env)->CallObjectMethod(env, value, getBytesMethodId);
      |                                                                          ^~~
```

Newer clang versions complain with:

```
org_gnu_readline_Readline.c:780:54: warning: passing 'const JNIEnv *' (aka 'const struct JNINativeInterface_ *const *') to parameter of type 'JNIEnv *' (aka 'const struct JNINativeInterface_ **') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
  780 |   const jclass jstringClass = (*env)->GetObjectClass(env, value);
      |                                                      ^~~
org_gnu_readline_Readline.c:781:58: warning: passing 'const JNIEnv *' (aka 'const struct JNINativeInterface_ *const *') to parameter of type 'JNIEnv *' (aka 'const struct JNINativeInterface_ **') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
  781 |   const jmethodID getBytesMethodId = (*env)->GetMethodID(env, jstringClass, "getBytes", "()[B");
      |                                                          ^~~
org_gnu_readline_Readline.c:783:74: warning: passing 'const JNIEnv *' (aka 'const struct JNINativeInterface_ *const *') to parameter of type 'JNIEnv *' (aka 'const struct JNINativeInterface_ **') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
  783 |   const jbyteArray jstringJBytes = (jbyteArray) (*env)->CallObjectMethod(env, value, getBytesMethodId);
      |                                                                          ^~~
```

Related to #41
@aclemons aclemons mentioned this issue Dec 12, 2024
Merged
aclemons added a commit that referenced this issue Dec 12, 2024
@aclemons
Remove const ptr declaration from fromjstring/tojstring functions.
73e5c52 
I thought I had resolved the warning here in 8078536, but it is still a
warning when using `env` inside of these functions by passing them into
say `GetObjectClass` etc.

Removing `const` completely silences any warnings.

Related to #41
aclemons added a commit that referenced this issue Dec 12, 2024
@aclemons
Correctly declare const ptrs in fromjstring/tojstring functions.
ee73b60 
I removed this in 73e5c52, but I actually just needed to declare it
correct as:

```c
static char* fromjstring(JNIEnv *const env, jstring value);
static jstring tojstring(JNIEnv *const env, const char* value);
```

This is what actually meant to do in 8078536, but failed to do.

Related to #41
aclemons added a commit that referenced this issue Dec 12, 2024
@aclemons
Fix type declaration for value returned by GetByteArrayElements.
99fe57e 
It returns a poineter to a jbyte, but it was incorrectly declared as a
pointer to a const jbyte.

The warning here is now resolved.

Related to #41.
@aclemons aclemons mentioned this issue Dec 12, 2024
Open
aclemons added a commit that referenced this issue Dec 12, 2024
@aclemons
Cast const char** in globalStringInternals to char**.
7e18ab1 
Newer compilers error on this. They should do that - the code is
incorrect - we are putting const char** values into this global array.
If someone uses setVarStringImpl to write to one of these, it will
crash.

This is however already mentioned in the documentation:

https://github.com/aclemons/java-readline/blob/99fe57e6c3544be476187fb7c66a664e6326c3ea/src/native/org_gnu_readline_Readline.c#L63-L64

and they all had a comment in front indicating they were:

```c
const `/* const */*
```

Basically we are relying on code using java-readline to not call the
wrong thing.

It has been this way for more than 20 years, so for now I will not
change this and will simply cast away the compiler error.

Related to #41
@aclemons
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Thanks @ebourg. I have handled all of these apart from:

org_gnu_readline_Readline.c:98:3: error: initialization of ‘int *’ from incompatible pointer type ‘long unsigned int *’ [-Wincompatible-pointer-types]
   98 |   &rl_readline_state,
      |   ^
org_gnu_readline_Readline.c:98:3: note: (near initialization for ‘globalIntegerInternals[2]’)

this is from an ABI change introduced in readline 7.0 where rl_readline_state changed from int to long unsigned int.

I raised an issue to track that (#45), and I need to think about how I best want to do it. I guess it will also be a breaking change for anything using java-readline if I bubble up the type change to java-readline's interface too.

@aclemons aclemons self-assigned this Dec 12, 2024
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