# Semantic analysis
In the semantic analysis step, the expl3 analysis tool determines the meaning of the different function calls.

## Functions and conditional functions

### Unused private function {.w label=w401 #unused-private-function}
A private function or conditional function name is defined but unused.

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### Unused private function variant {.w label=w402 #unused-private-function-variant}
A private function or conditional function variant name is defined but unused.

 /w402-01.tex
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### Function variant of incompatible type {.t label=t403}
A function or conditional function variant is generated from an incompatible argument type [@latexteam2024interfaces, Section 5.2, documentation of function `\cs_generate_variant:Nn`].

 /t403-01.tex

Higher-order variants can be created from existing variants as long as only `n` and `N` arguments are changed to other types:

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### Protected predicate function {.e label=e404}
A protected predicate function is defined.

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### Function variant for an undefined function {.e label=e405 #function-variant-for-undefined-function}
A function or conditional function variant is defined for an undefined function.

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### Calling an undefined function {.e label=e408 #calling-undefined-function}
A function or conditional function (variant) is called but undefined.

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### Function variant of deprecated type {.w label=w410}
A function or conditional function variant is generated from a deprecated argument type [@latexteam2024interfaces, Section 5.2, documentation of function `\cs_generate_variant:Nn`].

 /w410.tex

### Indirect function definition from an undefined function {.e label=e411 #indirect-function-definition-from-undefined-function}
A function or conditional function is indirectly defined from an undefined function.

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### Malformed function name {.s label=s412}
Some function have names that are not in the format `\texttt{\textbackslash\meta{module}\_\meta{description}:\meta{arg-spec}}`{=tex} [@latexteam2024programming, Section 3.2].

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This also extends to conditional functions:

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Furthermore, this also extends to function variants:

 /s412-08.tex

### Unexpandable or restricted-expandable boolean expression {.e label=e428 #unexpandable-or-restricted-expandable-boolean-expression}
A boolean expression [@latexteam2024interfaces, Section 9.2] is not fully-expandable.

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### Defined an unexpandable function as unprotected {.w label=w429 #defined-unexpandable-function-as-unprotected}
An unexpandable function or conditional function is defined using a creator function `\cs_new:*` or `\prg_new_conditional:*`. [@latexteam2024style, Section 4]

 /w429-01.tex
 /w429-02.tex

This issue is not raised for restricted-expandable functions:

 /w429-03.tex

## Variables and constants

### Malformed variable or constant name {.s label=s413}
Some expl3 variables and constants have names that are not in the format `\texttt{\textbackslash\meta{scope}\_\meta{module}\_\meta{description}\_\meta{type}}`{=tex} [@latexteam2024programming, Section 3.2].

 /s413-01.tex
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### Malformed quark or scan mark name {.s label=s414}
Some expl3 quarks and scan marks have names that do not start with `\q_` and `\s_`, respectively [@latexteam2024programming, Chapter 19].

 /s414-01.tex
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### Unused variable or constant {.w label=w415 #unused-variable-or-constant}
A variable or a constant name is declared and perhaps defined but unused.

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### Setting an undeclared variable {.w label=w416 #setting-undeclared-variable}
An undeclared variable is set.

 /w416.tex

### Setting a variable as a constant {.e label=e417 #setting-variable-as-constant}
A variable is set as though it were a constant.

 /e417.tex

### Setting a constant {.e label=e418}
A constant is set.

 /e418.tex

### Using an undeclared variable or constant {.w label=w419 #using-undeclared-variable-or-constant}
A variable or constant is used but undeclared or undefined.

 /w419-01.tex
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This also includes usage in `V`- and `v`-type arguments:

 /w419-06.tex

### Locally setting a global variable {.e label=e420}
A global variable is locally set.

 /e420.tex

### Globally setting a local variable {.e label=e421}
A local variable is globally set.

 /e421.tex

This issue should only be emitted if <#setting-variable-as-constant> has not previously been emitted for this variable.

### Using a variable of an incompatible type {.t label=t422}
A variable of one type is used where a variable of a different type should be used.

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## Messages

### Unused message {.w label=w423 #unused-message}
A message name is defined but unused.

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### Using an undefined message {.e label=e424 #using-undefined-message}
A message is used but undefined.

 /e424.tex

### Incorrect parameters in message text {.e label=e425 #invalid-parameters-in-message-text}
Parameter tokens other than `#1`, `#2`, `#3`, and `#4` are specified in a message text.

 /e425-01.tex
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### Incorrect number of arguments supplied to message {.w label=w426 #incorrect-number-of-arguments-supplied-to-message}
A message was supplied fewer or more arguments than there are parameters in the message text.

 /w426.tex

## Sorting
### Comparison conditional without signature `:nnTF` {.e label=e427}
A sorting function is called with a conditional that has a signature different than `:nnTF` [@latexteam2024interfaces, Section 15.5.4].

 /e427-01.tex
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