=== tests/cases/compiler/typeParameterCompatibilityAccrossDeclarations.ts === var a = { >a : { x: (y: T) => T; }, Symbol(a, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 0, 3)) >{ x: function (y: T): T { return null; }} : { x: (y: T) => T; } x: function (y: T): T { return null; } >x : (y: T) => T, Symbol(x, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 0, 9)) >function (y: T): T { return null; } : (y: T) => T >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 1, 16)) >y : T, Symbol(y, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 1, 19)) >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 1, 16)) >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 1, 16)) >null : null } var a2 = { >a2 : { x: (y: any) => any; }, Symbol(a2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 3, 3)) >{ x: function (y: any): any { return null; }} : { x: (y: any) => any; } x: function (y: any): any { return null; } >x : (y: any) => any, Symbol(x, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 3, 10)) >function (y: any): any { return null; } : (y: any) => any >y : any, Symbol(y, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 4, 16)) >null : null } export interface I { >I : I, Symbol(I, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 5, 1)) x(y: T): T; >x : (y: T) => T, Symbol(x, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 6, 20)) >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 7, 5)) >y : T, Symbol(y, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 7, 8)) >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 7, 5)) >T : T, Symbol(T, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 7, 5)) } export interface I2 { >I2 : I2, Symbol(I2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 8, 1)) x(y: any): any; >x : (y: any) => any, Symbol(x, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 9, 21)) >y : any, Symbol(y, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 10, 5)) } var i: I; >i : I, Symbol(i, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 13, 3)) >I : I, Symbol(I, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 5, 1)) var i2: I2; >i2 : I2, Symbol(i2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 14, 3)) >I2 : I2, Symbol(I2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 8, 1)) a = i; // error >a = i : I >a : { x: (y: T) => T; }, Symbol(a, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 0, 3)) >i : I, Symbol(i, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 13, 3)) i = a; // error >i = a : { x: (y: T) => T; } >i : I, Symbol(i, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 13, 3)) >a : { x: (y: T) => T; }, Symbol(a, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 0, 3)) a2 = i2; // no error >a2 = i2 : I2 >a2 : { x: (y: any) => any; }, Symbol(a2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 3, 3)) >i2 : I2, Symbol(i2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 14, 3)) i2 = a2; // no error >i2 = a2 : { x: (y: any) => any; } >i2 : I2, Symbol(i2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 14, 3)) >a2 : { x: (y: any) => any; }, Symbol(a2, Decl(typeParameterCompatibilityAccrossDeclarations.ts, 3, 3))