compiler does not throw "... has to be used or discarded" error when else branch raises error #23677

hamidb80 · 2024-06-04T13:38:44Z

Description

can catch this

if true:
  0
else: 
  echo "wow"

but not this:

if true:
  0
else: 
  raise newException(ValueError, "err")

Nim Version

Nim Compiler Version 2.1.1 [Windows: amd64]
Compiled at 2024-06-04
Copyright (c) 2006-2024 by Andreas Rumpf

active boot switches: -d:release

Current Output

compiles and runs

Expected Output

Error: expression '0' is of type 'int literal(0)' and has to be used (or discarded)

Possible Solution

No response

Additional Information

same with case of

The text was updated successfully, but these errors were encountered:

hamidb80 · 2024-06-04T13:41:08Z

!nim c

if true:
  0
else: 
  raise newException(ValueError, "err")

github-actions · 2024-06-04T13:41:56Z

🐧 Linux bisect by @hamidb80 (contributor)

devel 👍 OK

Output

IR

Compiled filesize 92.82 Kb (95,048 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
N_LIB_PRIVATE N_NIMCALL(void, nimTestErrorFlag)(void);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminusathdevelatslibatssystemdotnim_Init000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
#if 0
 void (*volatile inner)(void);
 inner = PreMainInner;
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminusathdevelatslibatssystemdotnim_Init000();
 (*inner)();
#else
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminusathdevelatslibatssystemdotnim_Init000();
 PreMainInner();
#endif
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
#if 0
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 (*inner)();
#else
 PreMain();
 NimMainInner();
#endif
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
 nimTestErrorFlag();
}
}

Stats

Started 2024-06-04T13:41:38
Finished 2024-06-04T13:41:38
Duration

stable 👍 OK

Output

IR

Compiled filesize 90.64 Kb (92,816 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
N_LIB_PRIVATE N_NIMCALL(void, nimTestErrorFlag)(void);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
#if 0
 void (*volatile inner)(void);
 inner = PreMainInner;
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000();
 (*inner)();
#else
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000();
 PreMainInner();
#endif
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
#if 0
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 (*inner)();
#else
 PreMain();
 NimMainInner();
#endif
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
 nimTestErrorFlag();
}
}

Stats

Started 2024-06-04T13:41:39
Finished 2024-06-04T13:41:40
Duration

2.0.4 👍 OK

Output

IR

Compiled filesize 90.64 Kb (92,816 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
N_LIB_PRIVATE N_NIMCALL(void, nimTestErrorFlag)(void);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
#if 0
 void (*volatile inner)(void);
 inner = PreMainInner;
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000();
 (*inner)();
#else
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot4atslibatssystemdotnim_Init000();
 PreMainInner();
#endif
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
#if 0
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 (*inner)();
#else
 PreMain();
 NimMainInner();
#endif
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
 nimTestErrorFlag();
}
}

Stats

Started 2024-06-04T13:41:40
Finished 2024-06-04T13:41:40
Duration

2.0.0 👍 OK

Output

IR

Compiled filesize 90.64 Kb (92,816 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
N_LIB_PRIVATE N_NIMCALL(void, nimTestErrorFlag)(void);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot0atslibatssystemdotnim_Init000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
#if 0
 void (*volatile inner)(void);
 inner = PreMainInner;
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot0atslibatssystemdotnim_Init000();
 (*inner)();
#else
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus2dot0dot0atslibatssystemdotnim_Init000();
 PreMainInner();
#endif
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
#if 0
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 (*inner)();
#else
 PreMain();
 NimMainInner();
#endif
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
 nimTestErrorFlag();
}
}

Stats

Started 2024-06-04T13:41:44
Finished 2024-06-04T13:41:44
Duration

1.6.20 👍 OK

Output

IR

Compiled filesize 95.50 Kb (97,792 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
#define nimfr_(x, y)
#define nimln_(x, y)
static N_INLINE(void, initStackBottomWith)(void* locals);
N_LIB_PRIVATE N_NOINLINE(void, nimGC_setStackBottom)(void* theStackBottom);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus1dot6dot20atslibatssystemdotnim_DatInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus1dot6dot20atslibatssystemdotnim_Init000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
static N_INLINE(void, initStackBottomWith)(void* locals) {
 nimGC_setStackBottom(locals);
}
N_LIB_PRIVATE void PreMainInner(void) {
}
 N_LIB_PRIVATE int cmdCount;
 N_LIB_PRIVATE char** cmdLine;
 N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
 void (*volatile inner)(void);
 inner = PreMainInner;
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus1dot6dot20atslibatssystemdotnim_DatInit000();
 initStackBottomWith((void *)&inner);
 atmdotdotatsdotdotatsdotdotatsdotchoosenimatstoolchainsatsnimminus1dot6dot20atslibatssystemdotnim_Init000();
 (*inner)();
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 initStackBottomWith((void *)&inner);
 (*inner)();
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
}
}

Stats

Started 2024-06-04T13:41:47
Finished 2024-06-04T13:41:47
Duration

1.4.8 👍 OK

Output

IR

Compiled filesize 91.16 Kb (93,344 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
#define nimfr_(x, y)
#define nimln_(x, y)
static N_INLINE(void, initStackBottomWith)(void* locals);
N_LIB_PRIVATE N_NOINLINE(void, nimGC_setStackBottom)(void* theStackBottom);
N_LIB_PRIVATE N_NIMCALL(void, systemDatInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, systemInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
static N_INLINE(void, initStackBottomWith)(void* locals) {
 nimGC_setStackBottom(locals);
}
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
 void (*volatile inner)(void);
 inner = PreMainInner;
 systemDatInit000();
 initStackBottomWith((void *)&inner);
 systemInit000();
 (*inner)();
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 initStackBottomWith((void *)&inner);
 (*inner)();
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
}
}

Stats

Started 2024-06-04T13:41:49
Finished 2024-06-04T13:41:50
Duration

1.2.18 👍 OK

Output

IR

Compiled filesize 86.88 Kb (88,968 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
#define nimfr_(x, y)
#define nimln_(x, y)
static N_INLINE(void, initStackBottomWith)(void* locals);
N_LIB_PRIVATE N_NOINLINE(void, nimGC_setStackBottom)(void* theStackBottom);
N_LIB_PRIVATE N_NIMCALL(void, systemDatInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, systemInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
static N_INLINE(void, initStackBottomWith)(void* locals) {
 nimGC_setStackBottom(locals);
}
N_LIB_PRIVATE void PreMainInner(void) {
}
N_LIB_PRIVATE int cmdCount;
N_LIB_PRIVATE char** cmdLine;
N_LIB_PRIVATE char** gEnv;
N_LIB_PRIVATE void PreMain(void) {
 void (*volatile inner)(void);
 inner = PreMainInner;
 systemDatInit000();
 initStackBottomWith((void *)&inner);
 systemInit000();
 (*inner)();
}
N_LIB_PRIVATE N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 initStackBottomWith((void *)&inner);
 (*inner)();
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
}
}

Stats

Started 2024-06-04T13:41:52
Finished 2024-06-04T13:41:53
Duration

1.0.10 👍 OK

Output

IR

Compiled filesize 81.98 Kb (83,952 bytes)

#define NIM_INTBITS 64
#include "nimbase.h"
#define nimfr_(x, y)
#define nimln_(x, y)
static N_INLINE(void, initStackBottomWith)(void* locals);
N_NOINLINE(void, nimGC_setStackBottom)(void* theStackBottom);
N_LIB_PRIVATE N_NIMCALL(void, systemDatInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, systemInit000)(void);
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void);
static N_INLINE(void, initStackBottomWith)(void* locals) {	nimGC_setStackBottom(locals);
}
void PreMainInner(void) {
}
int cmdCount;
char** cmdLine;
char** gEnv;
void PreMain(void) {
 void (*volatile inner)(void);
 inner = PreMainInner;
 systemDatInit000();
 initStackBottomWith((void *)&inner);
 systemInit000();
 (*inner)();
}
N_CDECL(void, NimMainInner)(void) {
 NimMainModule();
}
N_CDECL(void, NimMain)(void) {
 void (*volatile inner)(void);
 PreMain();
 inner = NimMainInner;
 initStackBottomWith((void *)&inner);
 (*inner)();
}
int main(int argc, char** args, char** env) {
 cmdLine = args;
 cmdCount = argc;
 gEnv = env;
 NimMain();
 return nim_program_result;
}
N_LIB_PRIVATE N_NIMCALL(void, NimMainModule)(void) {
{
}
}

Stats

Started 2024-06-04T13:41:55
Finished 2024-06-04T13:41:55
Duration

Stats

GCC 11.4.0
Clang 14.0.0
NodeJS 20.3
Created 2024-06-04T13:41:08Z
Comments 1
Commands nim c --run -d:nimDebug -d:nimDebugDlOpen -d:ssl -d:nimDisableCertificateValidation --forceBuild:on --colors:off --verbosity:0 --hints:off --lineTrace:off --nimcache:/home/runner/work/Nim/Nim --out:/home/runner/work/Nim/Nim/temp /home/runner/work/Nim/Nim/temp.nim

🤖 Bug found in 21 minutes bisecting 8 commits at 0 commits per second

metagn · 2024-06-04T13:58:59Z

~~This is intentional, the else branch cannot have a value since it halts execution~~ I misunderstood, the if expression is supposed to be a statement here

hamidb80 · 2024-06-04T15:32:34Z

This is intentional, the else branch cannot have a value since it halts execution

The problem is that if you write

0 
echo "Hi"

The compiler says you have to use it or discard it.

but when you write:

if   a: 0
elif b: 1
elif c: 2
else: raise ...

echo "Hi again"

it compiles!!!
isn't the if branch an expression?

juancarlospaco · 2024-06-04T16:15:03Z

0 
echo "Hi"

Theres clearly an unused integer literal there.

hamidb80 · 2024-06-04T17:54:24Z

Theres clearly an unused integer literal there.

what about here?

if   a: 0
elif b: 1
elif c: 2
else: raise ...

fixes nim-lang#10440, fixes nim-lang#13871, fixes nim-lang#14665, fixes nim-lang#19672, fixes nim-lang#23677

fixes #10440, fixes #13871, fixes #14665, fixes #19672, fixes #23677 The false positive in #23677 was caused by behavior in `implicitlyDiscardable` where only the last node of `if`/`case`/`try` etc expressions were considered, as in the final node of the final branch (in this case `else`). To fix this we use the same iteration in `implicitlyDiscardable` that we use in `endsInNoReturn`, with the difference that for an `if`/`case`/`try` statement to be implicitly discardable, all of its branches must be implicitly discardable. `noreturn` calls are also considered implicitly discardable for this reason, otherwise stuff like `if true: discardableCall() else: error()` doesn't compile. However `endsInNoReturn` also had bugs, one where `finally` was considered in noreturn checking when it shouldn't, another where only `nkIfStmt` was checked and not `nkIfExpr`, and the node given for the error message was bad. So `endsInNoReturn` now skips over `skipForDiscardable` which no longer contains `nkIfStmt`/`nkCaseStmt`/`nkTryStmt`, stores the first encountered returning node in a var parameter for the error message, and handles `finally` and `nkIfExpr`. Fixing #23677 already broke a line in `syncio` so some package code might be affected. (cherry picked from commit 42e8472)

metagn added a commit to metagn/Nim that referenced this issue Jun 4, 2024

fix noreturn/implicit discard check handling

5eb99e7

fixes nim-lang#10440, fixes nim-lang#13871, fixes nim-lang#14665, fixes nim-lang#19672, fixes nim-lang#23677

metagn mentioned this issue Jun 4, 2024

fix noreturn/implicit discard check logic #23681

Merged

Araq closed this as completed in #23681 Jun 5, 2024

Araq closed this as completed in 42e8472 Jun 5, 2024

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compiler does not throw "... has to be used or discarded" error when else branch raises error #23677

compiler does not throw "... has to be used or discarded" error when else branch raises error #23677

hamidb80 commented Jun 4, 2024

hamidb80 commented Jun 4, 2024

github-actions bot commented Jun 4, 2024

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metagn commented Jun 4, 2024 •

edited

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hamidb80 commented Jun 4, 2024 •

edited

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juancarlospaco commented Jun 4, 2024

hamidb80 commented Jun 4, 2024

compiler does not throw "... has to be used or discarded" error when else branch raises error #23677

compiler does not throw "... has to be used or discarded" error when else branch raises error #23677

Comments

hamidb80 commented Jun 4, 2024

Description

Nim Version

Current Output

Expected Output

Possible Solution

Additional Information

hamidb80 commented Jun 4, 2024

github-actions bot commented Jun 4, 2024

Output

IR

Stats

Output

IR

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Output

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Output

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metagn commented Jun 4, 2024 • edited Loading

hamidb80 commented Jun 4, 2024 • edited Loading

juancarlospaco commented Jun 4, 2024

hamidb80 commented Jun 4, 2024

metagn commented Jun 4, 2024 •

edited

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hamidb80 commented Jun 4, 2024 •

edited

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