Commit Graph

13 Commits

Author SHA1 Message Date
Yuanfang Chen 27a972a699 Diagnose -Wunused-value based on CFG reachability
(This relands 59337263ab and makes sure comma operator
 diagnostics are suppressed in a SFINAE context.)

While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.

This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D103938
2021-09-28 10:00:15 -07:00
Yuanfang Chen 59337263ab Revert "Diagnose -Wunused-value based on CFG reachability"
This reverts commit cbbf2e8c8a.
It seems causing diagnoses in SFINAE context.
2021-09-23 11:12:00 -07:00
Yuanfang Chen cbbf2e8c8a Diagnose -Wunused-value based on CFG reachability
While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.

This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D103938
2021-09-22 14:38:06 -07:00
Aaron Ballman 73a8bcd789 Revert "Diagnose -Wunused-value based on CFG reachability"
This reverts commit 63e0d038fc.

It causes test failures:

http://lab.llvm.org:8011/#/builders/119/builds/5612
https://logs.chromium.org/logs/fuchsia/buildbucket/cr-buildbucket/8835548361443044001/+/u/clang/test/stdout
2021-09-21 12:25:13 -04:00
Yuanfang Chen 63e0d038fc Diagnose -Wunused-value based on CFG reachability
While at it, add the diagnosis message "left operand of comma operator has no effect" (used by GCC) for comma operator.

This also makes Clang diagnose in the constant evaluation context which aligns with GCC/MSVC behavior. (https://godbolt.org/z/7zxb8Tx96)

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D103938
2021-09-20 10:43:34 -07:00
Aaron Ballman 6c93b3e29c Adding a -Wunused-value warning for expressions with side effects used in an unevaluated expression context, such as sizeof(), or decltype(). Also adds a similar warning when the expression passed to typeid() *is* evaluated, since it is equally likely that the user would expect the expression operand to be unevaluated in that case.
llvm-svn: 224465
2014-12-17 21:57:17 +00:00
Ted Kremenek e96dad9544 Don't warn about unused values in ternary ?: expressions unless both the LHS and RHS are "unused" (side-effect free).
Patch by Justin Bogner!  Fixes PR 8282.

llvm-svn: 126779
2011-03-01 20:34:48 +00:00
Argyrios Kyrtzidis 72664df103 Implement -Wunused-label.
llvm-svn: 114315
2010-09-19 21:21:25 +00:00
Argyrios Kyrtzidis 9096341310 Warn when an expression result in a LabelStmt is unused.
llvm-svn: 114314
2010-09-19 21:21:10 +00:00
Argyrios Kyrtzidis 639ffb0c07 Fix rdar://8139785 "implement warning on dead expression in comma operator"
As a bonus, fix the warning for || and && operators; it was emitted even if one of the operands had side effects, e.g:

x || test_logical_foo1();

emitted a bogus "expression result unused" for 'x'.

llvm-svn: 107274
2010-06-30 10:53:14 +00:00
Ted Kremenek a1de6fc575 Include all warnings under '-Wunused' in '-Wmost' and '-Wall'.
llvm-svn: 100786
2010-04-08 17:54:28 +00:00
Ted Kremenek 43a9c9626f Don't emit an 'unused expression' warning for '||' and '&&' expressions that contain assignments
or similar side-effects.

llvm-svn: 100676
2010-04-07 18:49:21 +00:00
John McCall c493a73240 Improve the unused-value check to look into comma expressions and filter out
voids in sub-expressions.  Patch by Mike M!

Fixes PR4806.

llvm-svn: 98335
2010-03-12 07:11:26 +00:00