Problems building a simple cgo module-CodePudding

Ubuntu. vscode 1.62.1. go1.17.3. vscode go extension v0.29.0. delve v1.7.1.

I'm trying to a build a small app that uses Cgo, using vscode and vscode-go. Only one module imports "C".

My project structure has the root directory containing the "go.mod" and "main.go" files, and I have subpackages in subfolders. I also have "include" and "lib" directories that contain the C artifacts.

This is what I have so far in the C module:

package voltage

// #cgo CFLAGS: -g -Wall -Iinclude
// #cgo LDFLAGS: -Llib/linux -lvibesimple -lcurl -lssl -lvibecrypto -lvibeictk -lvibeserver
// #include <stdio.h>
// #include <errno.h>
// #include "veapi.h"
import "C"

func Encrypt(datatype string, data string) (result string) {
    return
}

func Decrypt(datatype string, data string) (result string) {
    return
}

In the "Problems" view, it shows the following two issues:

go list failed to return CompiledGoFiles. This may indicate failure to perform cgo processing; try building at the command line. See https://golang.org/issue/38990.

And:

could not import C (cgo preprocessing failed) (compile)

I read the cited issue, but I'm not sure what to do with that information.

I'm not sure how to move forward here.

CodePudding user response：

The C compiler is not executed in the source directory but in a temporary directory only containing intermediate files, such as your go files compiled as static libraries (.a). Therefore, the LDFLAG -Llib/linux points to an unexisting directory.

To solve this issue, just replace that flag with -L${SRCDIR}/lib/linux.

Directly from the cgo docs:

When the cgo directives are parsed, any occurrence of the string ${SRCDIR} will be replaced by the absolute path to the directory containing the source file. This allows pre-compiled static libraries to be included in the package directory and linked properly.

The cgo tool will always invoke the C compiler with the source file's directory in the include path; i.e. -I${SRCDIR} is always implied.