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Manual; Attempt to clarify section about automatic preprocessor defines configuration

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Daniel Marjamäki 2021-02-06 13:35:12 +01:00
parent 7ab70654ba
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1 changed files with 18 additions and 23 deletions
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man/manual.md
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@ -310,7 +310,7 @@ likely you don't have to configure anything extra.
If you don't use `--project` then a bit of manual preprocessor configuration might be required. However Cppcheck has If you don't use `--project` then a bit of manual preprocessor configuration might be required. However Cppcheck has
automatic configuration of defines. automatic configuration of defines.
## Automatic configuration of -D ## Automatic configuration of preprocessor defines
Here is a file that has 3 bugs (when x,y,z are assigned). Here is a file that has 3 bugs (when x,y,z are assigned).
@ -323,35 +323,30 @@ Here is a file that has 3 bugs (when x,y,z are assigned).
z=100/0; z=100/0;
#endif #endif
Before the code is preprocessed, Cppcheck will by default look at what preprocessor conditions there are and generate #ifndef C
a list of suitable preprocessor configurations. For the example code above, all bugs can be found if we check for #error C must be defined
instance the configurations "" and "A;B". #endif
Cppcheck will by default not try to check configurations that contain `#error`.
Check all code: To find all bugs the code must be preprocessed both with "-DC" and with "-DA -DB -DC".
cppcheck file.c Cppcheck automatically determines what combinations of defines are necessary to analyze all the code. The example code
=> All bugs are reported above will by default automatically be preprocessed and analyzed multiple times.
### Limit automatic configurations You can manually configure what combinations are checked with `-D`, `-U`, `--max-configs` and `--force`.
To specify a preprocessor define you can use `-D`. The flag `-D` tells Cppcheck that a name is defined.
The flag `-U` will tell Cppcheck that a name is not defined.
The flag `--force` and `--max-configs` is used to control how many combinations are checked. When `-D` is used,
Cppcheck will only check 1 configuration unless these are used.
If there is an explicit configuration on the command line then Cppcheck will only that and nothing else. Example:
cppcheck -DA file.c cppcheck test.c => all bugs are found
=> Only first bug is found cppcheck -DA test.c => No bug is found (#error)
cppcheck -DA -DC test.c => The first bug is found
You can use `--force` to tell Cppcheck that you do want to check several configurations cppcheck -UA test.c => The last bug is found
cppcheck --force -DA test.c => The two first bugs are found
cppcheck -DA --force file.c
=> The first 2 bugs are found (if A is defined then the last bug never happens).
To exclude a certain define you can use `-U`. It tells Cppcheck that a macro is never defined. Example usage:
cppcheck -UA file.c
=> Cppcheck will only report the last bug.
## Include paths ## Include paths