Why Aren't My Makefile Expressions Evaluating Correctly?

Evaluating Expressions in Makefile Commands

Makefiles are powerful tools for automating build processes. However, when writing Makefile recipes, it's important to understand how expressions are evaluated.

In a Makefile recipe section, the dollar sign ($) is used to interpolate variables. To interpolate an expression that involves a command, you need to escape the $ using a second $:

Problem: Using an expression in a Makefile command, but the expression is not being evaluated.

Command:

test:
    go test $(go list ./... | grep -v /vendor/)

Issue: The expression is enclosed in parentheses, which prevents it from being expanded.

Solution: Escape the dollar sign using another dollar sign ($):

test:
    go test $$(go list ./... | grep -v /vendor/)

Now, the Makefile will correctly evaluate the expression and run the go test command with the filtered test files.

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