# [PATCH] Mark win32's pthread_exit() as NORETURN 12 messages from 2016-03-01 to 2016-03-02. Participants: Johannes Schindelin, Jeff King, stefan.naewe@atlas-elektronik.com, Junio C Hamano, Johannes Sixt. Thread: https://gitlist.dev/t/41580 ## Johannes Schindelin, 2016-03-01 13:53 Subject: [PATCH] Mark win32's pthread_exit() as NORETURN Message-ID: <69eef72cfc77e62ad7ad17c6df5f2d2396c64991.1456840324.git.johannes.schindelin@gmx.de> URL: https://gitlist.dev/e/69eef72cfc77e62ad7ad17c6df5f2d2396c64991.1456840324.git.johannes.schindelin%40gmx.de ``` The pthread_exit() function is not expected to return. Ever. Pointed out by Jeff King. Signed-off-by: Johannes Schindelin --- compat/win32/pthread.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h index 20b35a2..148db60 100644 --- a/compat/win32/pthread.h +++ b/compat/win32/pthread.h @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) extern pthread_t pthread_self(void); -static inline int pthread_exit(void *ret) +static inline int NORETURN pthread_exit(void *ret) { ExitThread((DWORD)(intptr_t)ret); } -- 2.7.2.windows.1.5.g64acc33 ``` ## Jeff King, 2016-03-01 13:57 Subject: Re: [PATCH] Mark win32's pthread_exit() as NORETURN Message-ID: <20160301135708.GA29303@sigill.intra.peff.net> URL: https://gitlist.dev/e/20160301135708.GA29303%40sigill.intra.peff.net In-Reply-To: <69eef72cfc77e62ad7ad17c6df5f2d2396c64991.1456840324.git.johannes.schindelin@gmx.de> ``` On Tue, Mar 01, 2016 at 02:53:04PM +0100, Johannes Schindelin wrote: > The pthread_exit() function is not expected to return. Ever. > > Pointed out by Jeff King. > > Signed-off-by: Johannes Schindelin > --- > compat/win32/pthread.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > index 20b35a2..148db60 100644 > --- a/compat/win32/pthread.h > +++ b/compat/win32/pthread.h > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > extern pthread_t pthread_self(void); > > -static inline int pthread_exit(void *ret) > +static inline int NORETURN pthread_exit(void *ret) > { > ExitThread((DWORD)(intptr_t)ret); > } Looks obviously correct to me (I'll assume Windows isn't so crazy as to let ExitThread ever return :) ). -Peff > -- > 2.7.2.windows.1.5.g64acc33 ``` ## Johannes Schindelin, 2016-03-01 14:11 Subject: Re: [PATCH] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/alpine.DEB.2.20.1603011511050.3152%40virtualbox In-Reply-To: <20160301135708.GA29303@sigill.intra.peff.net> ``` Hi Peff, On Tue, 1 Mar 2016, Jeff King wrote: > On Tue, Mar 01, 2016 at 02:53:04PM +0100, Johannes Schindelin wrote: > > > The pthread_exit() function is not expected to return. Ever. > > > > Pointed out by Jeff King. > > > > Signed-off-by: Johannes Schindelin > > --- > > compat/win32/pthread.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > > index 20b35a2..148db60 100644 > > --- a/compat/win32/pthread.h > > +++ b/compat/win32/pthread.h > > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > > extern pthread_t pthread_self(void); > > > > -static inline int pthread_exit(void *ret) > > +static inline int NORETURN pthread_exit(void *ret) > > { > > ExitThread((DWORD)(intptr_t)ret); > > } > > Looks obviously correct to me (I'll assume Windows isn't so crazy as to > let ExitThread ever return :) ). Indeed, you are correct in your implicit assumption that I should have clarified that in my commit message. I will amend the commit message. Ciao, Dscho ``` ## Johannes Schindelin, 2016-03-01 14:13 Subject: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/d584d8bdaa8645a406c96f2a11f04febf57b2c25.1456841593.git.johannes.schindelin%40gmx.de In-Reply-To: <69eef72cfc77e62ad7ad17c6df5f2d2396c64991.1456840324.git.johannes.schindelin@gmx.de> ``` The pthread_exit() function is not expected to return. Ever. On Windows, we call ExitThread() whose documentation claims: "This function does not return a value.": https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 Pointed out by Jeff King. Signed-off-by: Johannes Schindelin --- Relative to v1, only the commit message changed (to clarify that ExitThread() indeed never returns). compat/win32/pthread.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h index 20b35a2..148db60 100644 --- a/compat/win32/pthread.h +++ b/compat/win32/pthread.h @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) extern pthread_t pthread_self(void); -static inline int pthread_exit(void *ret) +static inline int NORETURN pthread_exit(void *ret) { ExitThread((DWORD)(intptr_t)ret); } -- 2.7.2.windows.1.5.g64acc33 ``` ## stefan.naewe@atlas-elektronik.com, 2016-03-01 14:38 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: <56D5A955.8010904@atlas-elektronik.com> URL: https://gitlist.dev/e/56D5A955.8010904%40atlas-elektronik.com In-Reply-To: ``` Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: > The pthread_exit() function is not expected to return. Ever. On Windows, > we call ExitThread() whose documentation claims: "This function does not > return a value.": Does this really mean that ExitThread() does not return ? Just wondering... > https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 > > Pointed out by Jeff King. > > Signed-off-by: Johannes Schindelin > --- > > Relative to v1, only the commit message changed (to clarify that > ExitThread() indeed never returns). > > compat/win32/pthread.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > index 20b35a2..148db60 100644 > --- a/compat/win32/pthread.h > +++ b/compat/win32/pthread.h > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > extern pthread_t pthread_self(void); > > -static inline int pthread_exit(void *ret) > +static inline int NORETURN pthread_exit(void *ret) > { > ExitThread((DWORD)(intptr_t)ret); > } > -- Stefan -- ---------------------------------------------------------------- /dev/random says: We're lost, but we're making good time. python -c "print '73746566616e2e6e616577654061746c61732d656c656b74726f6e696b2e636f6d'.decode('hex')" GPG Key fingerprint = 2DF5 E01B 09C3 7501 BCA9 9666 829B 49C5 9221 27AF ``` ## Junio C Hamano, 2016-03-01 17:57 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/xmqq60x684j3.fsf%40gitster.mtv.corp.google.com In-Reply-To: <56D5A955.8010904@atlas-elektronik.com> ``` writes: > Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: >> The pthread_exit() function is not expected to return. Ever. On Windows, >> we call ExitThread() whose documentation claims: "This function does not >> return a value.": > > Does this really mean that ExitThread() does not return ? > > Just wondering... ;-). That made me re-read the patch and notice another thing... Dscho, I think you would need s/int/void/, too, no? > >> https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 >> >> Pointed out by Jeff King. >> >> Signed-off-by: Johannes Schindelin >> --- >> >> Relative to v1, only the commit message changed (to clarify that >> ExitThread() indeed never returns). >> >> compat/win32/pthread.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h >> index 20b35a2..148db60 100644 >> --- a/compat/win32/pthread.h >> +++ b/compat/win32/pthread.h >> @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); >> #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) >> extern pthread_t pthread_self(void); >> >> -static inline int pthread_exit(void *ret) >> +static inline int NORETURN pthread_exit(void *ret) >> { >> ExitThread((DWORD)(intptr_t)ret); >> } >> -- > > > Stefan ``` ## Johannes Sixt, 2016-03-01 19:34 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: <56D5EEE2.3080100@kdbg.org> URL: https://gitlist.dev/e/56D5EEE2.3080100%40kdbg.org In-Reply-To: ``` Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: > The pthread_exit() function is not expected to return. Ever. On Windows, > we call ExitThread() whose documentation claims: "This function does not > return a value.": > > https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 This is misleading: MSDN marks all functions declared void as "does not return a value," for example, look at EnterCriticalSection: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682608 For this reason, I actually prefer your version 1 patch without the explanation. > > Pointed out by Jeff King. > > Signed-off-by: Johannes Schindelin > --- > > Relative to v1, only the commit message changed (to clarify that > ExitThread() indeed never returns). > > compat/win32/pthread.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > index 20b35a2..148db60 100644 > --- a/compat/win32/pthread.h > +++ b/compat/win32/pthread.h > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > extern pthread_t pthread_self(void); > > -static inline int pthread_exit(void *ret) > +static inline int NORETURN pthread_exit(void *ret) I would have written it as #ifdef __GNUC__ __attribute__((__noreturn__)) #endif static inline int pthread_exit(void *ret) ... but I can live with your version as long as it compiles. Your solution is pragmatic: NORETURN is defined in git-compat-util.h, and by using it here, we depend on that pthread.h is included sufficiently late that the macro is available at this point. The instance in compat/nedmalloc/malloc.c.h is bracketed with #ifndef WIN32 so that it is not compiled on Windows, all other instances are after git-compat-util.h or cache.h or in headers that are to be included only after git-compat-util.h or cache.h per convention. Looks like we are safe. > { > ExitThread((DWORD)(intptr_t)ret); > } > ``` ## Junio C Hamano, 2016-03-01 19:44 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/xmqqio166l0n.fsf%40gitster.mtv.corp.google.com In-Reply-To: <56D5EEE2.3080100@kdbg.org> ``` Johannes Sixt writes: > Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: >> The pthread_exit() function is not expected to return. Ever. On Windows, >> we call ExitThread() whose documentation claims: "This function does not >> return a value.": >> >> https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 > > This is misleading: MSDN marks all functions declared void as "does > not return a value," for example, look at EnterCriticalSection: > > https://msdn.microsoft.com/en-us/library/windows/desktop/ms682608 > > For this reason, I actually prefer your version 1 patch without the > explanation. ;-) >> -static inline int pthread_exit(void *ret) >> +static inline int NORETURN pthread_exit(void *ret) > > I would have written it as > > #ifdef __GNUC__ > __attribute__((__noreturn__)) > #endif > static inline int pthread_exit(void *ret) ... > > but I can live with your version as long as it compiles. Either way, let's make sure that the final version returns "void", cf. http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_exit.html Thanks. ``` ## Johannes Schindelin, 2016-03-02 19:10 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/alpine.DEB.2.20.1603022008240.3152%40virtualbox In-Reply-To: ``` Hi, On Tue, 1 Mar 2016, Junio C Hamano wrote: > Johannes Sixt writes: > > > Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: > >> The pthread_exit() function is not expected to return. Ever. On Windows, > >> we call ExitThread() whose documentation claims: "This function does not > >> return a value.": > >> > >> https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 > > > > This is misleading: MSDN marks all functions declared void as "does > > not return a value," for example, look at EnterCriticalSection: > > > > https://msdn.microsoft.com/en-us/library/windows/desktop/ms682608 > > > > For this reason, I actually prefer your version 1 patch without the > > explanation. > > ;-) Well, I really like to have that link so I can find it very easily myself by simply inspecting the Git log. And the explanation itself was easily fixed. > > >> -static inline int pthread_exit(void *ret) > >> +static inline int NORETURN pthread_exit(void *ret) > > > > I would have written it as > > > > #ifdef __GNUC__ > > __attribute__((__noreturn__)) > > #endif > > static inline int pthread_exit(void *ret) ... > > > > but I can live with your version as long as it compiles. > > Either way, let's make sure that the final version returns "void", > cf. > > http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_exit.html Fixed, too, in the upcoming v3. Ciao, Dscho ``` ## Johannes Schindelin, 2016-03-02 19:11 Subject: Re: [PATCH v2] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/alpine.DEB.2.20.1603022010410.3152%40virtualbox In-Reply-To: <56D5A955.8010904@atlas-elektronik.com> ``` Hi, On Tue, 1 Mar 2016, stefan.naewe@atlas-elektronik.com wrote: > Am 01.03.2016 um 15:13 schrieb Johannes Schindelin: > > The pthread_exit() function is not expected to return. Ever. On Windows, > > we call ExitThread() whose documentation claims: "This function does not > > return a value.": > > Does this really mean that ExitThread() does not return ? I fixed the commit message in v3. Thanks, Dscho ``` ## Johannes Schindelin, 2016-03-02 19:11 Subject: [PATCH v3] Mark win32's pthread_exit() as NORETURN Message-ID: <63310f6af16c70870bd620c83d8860421ca02718.1456945703.git.johannes.schindelin@gmx.de> URL: https://gitlist.dev/e/63310f6af16c70870bd620c83d8860421ca02718.1456945703.git.johannes.schindelin%40gmx.de In-Reply-To: ``` The pthread_exit() function is not expected to return. Ever. On Windows, we call ExitThread() whose documentation claims: "Ends the calling thread", i.e. there is no condition in which this function simply returns: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 While at it, fix the return type to be void, as per http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_exit.html Pointed out by Jeff King, helped by Stefan Naewe, Junio Hamano & Johannes Sixt. Signed-off-by: Johannes Schindelin --- compat/win32/pthread.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Interdiff vs v2: diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h index 148db60..b6ed9e7 100644 --- a/compat/win32/pthread.h +++ b/compat/win32/pthread.h @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) extern pthread_t pthread_self(void); -static inline int NORETURN pthread_exit(void *ret) +static inline void NORETURN pthread_exit(void *ret) { ExitThread((DWORD)(intptr_t)ret); } diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h index 20b35a2..b6ed9e7 100644 --- a/compat/win32/pthread.h +++ b/compat/win32/pthread.h @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) extern pthread_t pthread_self(void); -static inline int pthread_exit(void *ret) +static inline void NORETURN pthread_exit(void *ret) { ExitThread((DWORD)(intptr_t)ret); } -- 2.7.2.windows.1.5.g64acc33 ``` ## Junio C Hamano, 2016-03-02 20:33 Subject: Re: [PATCH v3] Mark win32's pthread_exit() as NORETURN Message-ID: URL: https://gitlist.dev/e/xmqq7fhk4o38.fsf%40gitster.mtv.corp.google.com In-Reply-To: <63310f6af16c70870bd620c83d8860421ca02718.1456945703.git.johannes.schindelin@gmx.de> ``` Johannes Schindelin writes: > The pthread_exit() function is not expected to return. Ever. On Windows, > we call ExitThread() whose documentation claims: "Ends the calling > thread", i.e. there is no condition in which this function simply > returns: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659 > > While at it, fix the return type to be void, as per > http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_exit.html > > Pointed out by Jeff King, helped by Stefan Naewe, Junio Hamano & > Johannes Sixt. > > Signed-off-by: Johannes Schindelin > --- Thanks, will queue. > compat/win32/pthread.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Interdiff vs v2: > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > index 148db60..b6ed9e7 100644 > --- a/compat/win32/pthread.h > +++ b/compat/win32/pthread.h > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > extern pthread_t pthread_self(void); > > -static inline int NORETURN pthread_exit(void *ret) > +static inline void NORETURN pthread_exit(void *ret) > { > ExitThread((DWORD)(intptr_t)ret); > } > > > diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h > index 20b35a2..b6ed9e7 100644 > --- a/compat/win32/pthread.h > +++ b/compat/win32/pthread.h > @@ -78,7 +78,7 @@ extern int win32_pthread_join(pthread_t *thread, void **value_ptr); > #define pthread_equal(t1, t2) ((t1).tid == (t2).tid) > extern pthread_t pthread_self(void); > > -static inline int pthread_exit(void *ret) > +static inline void NORETURN pthread_exit(void *ret) > { > ExitThread((DWORD)(intptr_t)ret); > } ```