This makes the code easier to read, especially in var.c. It also makes
debugging sessions easier since some debuggers don't show enum
bit-fields symbolically as soon as more than one bit is set.
The code outside var.c is basically unchanged, except that instead of
passing the individual flags, there are 4 predefined evaluation modes.
These suffice for all practical use cases. Only in the implementation
deep inside var.c, the value of the flags keepDollar and keepUndef
differs.
There is no way of passing the struct to EnumFlags_ToString, which means
the ToString function has to be spelled out explicitly. This allows for
fine-tuning the representation in the debug log, to reduce the amount of
uppercae letters.
No functional change.
The name 'NONE' described the bit pattern, which was not useful to
understand its meaning. Omitting VARE_WANTRES only parses the
expression, without evaluating any part of it.
No functional change, not even in debug mode since Enum_FlagsToString
always returns "none" for all-bits-unset.
some drivers (not hdaudio(4), but uaudio(4), eap(4), sb(4), various other
old cards) will return error if a AUDIO_MIXER_VALUE is requested and the
number of channels is not specified as input. this is not documented as
well as it should be, unfortunately.
This is just to keep the code consistent among the various variable
modifiers. The performance gain is negligible.
The actual assignment to the variable had already been skipped
previously.
No functional change.
No functional change in practical usage. Theoretically this change can
be observed by looking at the generated random numbers for the ':Ox'
modifier, but the quality or exact sequence of these random numbers is
not guaranteed anyway.
In parse-only mode, variable expressions in the argument to that
modifier are not resolved. This led to the error message about the 'Bad
modifier' in var-eval-short.mk.
This affects the modifiers ':E', ':H', ':P', ':Q', ':R', ':T', ':hash',
':q', ':range', ':tl', ':ts', ':tu', and ':u'. All these modifiers are
side-effect free.
Skipping the evaluation for these modifiers is purely for code
consistency and performance.
No functional change.
No functional change, just a tiny bit of performance improvement,
probably not even measurable. Having the code nevertheless serves as a
copy-and-paste template for implementing other modifiers that might
perform more costly tasks.
The test 'var-eval-short' had produced the output 'unexpected' before,
on stderr. It had been generated by '${:Uword:@${FAIL}@expr@}' by
combining the following obscure "features" of make:
1. the ':@' modifier loops over the words of the variable. This
modifier is not really obscure, it still takes some time to get used
to it.
2. the ':@' modifier allows a '$' sign in the variable name, which is
useless in practice.
3. the ':@' modifier creates a temporary loop variable in the global
namespace. Luckily there are only few collisions with other
variable names since their naming conventions differ.
4. after looping over the words of the expression, the temporary global
loop variable is deleted, and at that point the '$' is expanded,
being interpreted as the start of a variable expression.
5. The ':@' modifier deleted the global variable even when it was
called in parse-only mode (without VARE_WANTRES).
When the modifier ':@' was initially added to make in var.c 1.40 from
2000-04-29, Var_Delete didn't expand the variable name. That feature
was added in var.c 1.174 from 2013-05-18, probably without thinking of
this very edge-casey combination of features.
This commit fixes item 5 from the above list. The other obscurities
remain for now.
This way, parsing and evaluating the modifier is only written once in
the code. The downside is that the variable name is allocated even if
VARE_WANTRES is not set, but since this modifier is so obscure and
seldom used this doesn't matter in practice.
This edge case had been so obscure that even discovering this takes
quite some time and requires reading the source code of make.
The manual page doesn't document whether the variable name is expanded
or not, it doesn't even give an example. When this obscure modifier was
initially added in var.c 1.210 from 2017-01-30, Var_Set always expanded
the variable name once, and there was no way around it. Therefore this
expansion has probably been unintentional.
See var-eval-short.mk:46 for the test demonstrating this change.
Previously, the expression ${:Uword:_=VAR} was evaluated including all
its side effects even though it was in an irrelevant branch of the
condition.
No functional change since the only caller of TryParseIntBase0 already
handles all possible parse errors. Without this check, the code just
looked wrong though.
TryParseIntBase0 wrongly returns successful for a string that does not
start with a number at all. Its only caller, ApplyModifier_Words,
already handles all error cases properly.
No functional change.
This aligns the implementation of these modifiers with the requirements
in the long comment starting with 'The ApplyModifier functions'.
No functional change.
Right now, when a variable expression cannot be parsed, the result of
calling Var_Subst is a string containing garbage, and no error is
reported. In addition, there are some silent errors that are not
reported at all. This combination makes it difficult to change the
error handling without introducing subtle breakage in some edge cases.
An example for garbage output is in varmod-subst-regex.mk, in target
mod-regex-compile-error.
No functional change.
The modifier ':C' now only compiles the regular expression if the result
of the expression is actually needed.
Several other modifiers have the same bug of evaluating the expression
in cases where this is not needed. It just doesn't show up because they
don't have any noticeable side effects, other than wasting CPU time.
This affects irrelevant conditions as well.
