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| author | Brad King <brad.king@kitware.com> | 2022-02-09 19:16:50 (GMT) |
|---|---|---|
| committer | Brad King <brad.king@kitware.com> | 2022-02-09 19:24:43 (GMT) |
| commit | 41adfc6b041474f6985ab72efcfb02b2b64a6b8d (patch) | |
| tree | 3624c5d8c5f34145f26709cf164ee840210f1d19 | |
| parent | a15cc7706da8f4a1833539be3f37fbc63ee20e36 (diff) | |
| download | CMake-41adfc6b041474f6985ab72efcfb02b2b64a6b8d.zip CMake-41adfc6b041474f6985ab72efcfb02b2b64a6b8d.tar.gz CMake-41adfc6b041474f6985ab72efcfb02b2b64a6b8d.tar.bz2 | |
Help: Clarify precedence of AND and OR in 'if' conditions
The wording update in commit b74819e4fe (Help: Format 'if' command
documentation, 2013-12-18, v3.0.0-rc1~227^2~1) incorrectly implied that
`AND` has higher precedence than `OR`. Although this is common in many
languages, it has never been true in CMake's implementation. Revise
the wording to clarify the precedence.
Add a test case demonstrating the order.
Fixes: #23207
| -rw-r--r-- | Help/command/if.rst | 23 | ||||
| -rw-r--r-- | Tests/RunCMake/if/AndOr-stdout.txt | 1 | ||||
| -rw-r--r-- | Tests/RunCMake/if/AndOr.cmake | 6 | ||||
| -rw-r--r-- | Tests/RunCMake/if/RunCMakeTest.cmake | 2 |
4 files changed, 24 insertions, 8 deletions
diff --git a/Help/command/if.rst b/Help/command/if.rst index a729b1e..4f955db 100644 --- a/Help/command/if.rst +++ b/Help/command/if.rst @@ -38,14 +38,21 @@ The following syntax applies to the ``condition`` argument of the ``if``, ``elseif`` and :command:`while` clauses. Compound conditions are evaluated in the following order of precedence: -Innermost parentheses are evaluated first. Next come unary tests such -as `EXISTS`_, `COMMAND`_, and `DEFINED`_. Then binary tests such as -`EQUAL`_, `LESS`_, `LESS_EQUAL`_, `GREATER`_, `GREATER_EQUAL`_, -`STREQUAL`_, `STRLESS`_, `STRLESS_EQUAL`_, `STRGREATER`_, -`STRGREATER_EQUAL`_, `VERSION_EQUAL`_, `VERSION_LESS`_, -`VERSION_LESS_EQUAL`_, `VERSION_GREATER`_, `VERSION_GREATER_EQUAL`_, -and `MATCHES`_. Then the boolean operators in the order `NOT`_, `AND`_, -and finally `OR`_. + +1. Parentheses. + +2. Unary tests such as `EXISTS`_, `COMMAND`_, and `DEFINED`_. + +3. Binary tests such as `EQUAL`_, `LESS`_, `LESS_EQUAL`_, `GREATER`_, + `GREATER_EQUAL`_, `STREQUAL`_, `STRLESS`_, `STRLESS_EQUAL`_, + `STRGREATER`_, `STRGREATER_EQUAL`_, `VERSION_EQUAL`_, `VERSION_LESS`_, + `VERSION_LESS_EQUAL`_, `VERSION_GREATER`_, `VERSION_GREATER_EQUAL`_, + and `MATCHES`_. + +4. Unary logical operator `NOT`_. + +5. Binary logical operators `AND`_ and `OR`_, from left to right, + without any short-circuit. Basic Expressions """"""""""""""""" diff --git a/Tests/RunCMake/if/AndOr-stdout.txt b/Tests/RunCMake/if/AndOr-stdout.txt new file mode 100644 index 0000000..9fd395b --- /dev/null +++ b/Tests/RunCMake/if/AndOr-stdout.txt @@ -0,0 +1 @@ +-- OR and AND correctly evaluated left to right diff --git a/Tests/RunCMake/if/AndOr.cmake b/Tests/RunCMake/if/AndOr.cmake new file mode 100644 index 0000000..847d6f2 --- /dev/null +++ b/Tests/RunCMake/if/AndOr.cmake @@ -0,0 +1,6 @@ +# AND and OR are the same precedence +if(1 OR 0 AND 0) # equivalent to ((1 OR 0) AND 0) + message(FATAL_ERROR "AND incorrectly evaluated before OR") +else() + message(STATUS "OR and AND correctly evaluated left to right") +endif() diff --git a/Tests/RunCMake/if/RunCMakeTest.cmake b/Tests/RunCMake/if/RunCMakeTest.cmake index 6baa840..de9cb57 100644 --- a/Tests/RunCMake/if/RunCMakeTest.cmake +++ b/Tests/RunCMake/if/RunCMakeTest.cmake @@ -17,3 +17,5 @@ run_cmake(IncompleteMatchesFail) run_cmake(TestNameThatExists) run_cmake(TestNameThatDoesNotExist) + +run_cmake_script(AndOr) |